MK. MANAJEMEN SUMBERDAYA LAHAN & PENGEMBANGAN WILAYAH

MK. MANAJEMEN SUMBERDAYA LAHAN & PENGEMBANGAN WILAYAH
BAHAN KAJIAN MK. MANAJEMEN SUMBERDAYA LAHAN & PENGEMBANGAN WILAYAH PENGELOLAAN LAHAN SAWAH Diabstraksikan oleh: Soemarno, FEBR 2013

Lapisan-lapisan tanah ini dihubungkan oleh air perkolasi.
AGROEKOSISTEM SAWAH Ekosistem padi sawah terdiri atas air permukana, lapisan tanah olah dan subsoil, dan tanah olah yg dibagi menjadi dua lapisan; lapisan tipis tanah oksidasi dan lapisan tanah reduksi. Lapisan-lapisan tanah ini dihubungkan oleh air perkolasi. Selain itu, akar tanaman padi tumbuh-berkembang dan residu tganaman seperti jerami setelah panen dimasukkan ke dalam tanah lapisan olah. Tapak mikro ini merupakan habitat yang berbeda-beda bagi mikroba, dan komunitas mikroba yg unik ini menggantungkan hidupnya pada tapak-mikro tersebut. Diunduh dari sumber: …….. 28/10/2012

Lahan sawah irigasi sedang ditanami bawang merah
Sawah adalah lahan usaha pertanian yang secara fisik permukaan BIDANG OLAHNYA rata, dibatasi oleh pematang, serta dapat ditanami padi, palawija atau tanaman budidaya lainnya. Biasanya sawah digunakan untuk bercocok tanam padi. Untuk keperluan ini, sawah harus mampu menyangga genangan air karena padi memerlukan penggenangan pada periode tertentu dalam pertumbuhannya. Untuk mengairi sawah digunakan sistem irigasi dari mata air, sungai atau air hujan. Sawah yang airnya berasal dari hujan dikenal sebagai sawah tadah hujan, sementara yang lainnya adalah sawah irigasi. Padi yang ditanam di sawah dikenal sebagai padi lahan basah (lowland rice). Lahan sawah irigasi sedang ditanami bawang merah Foto: smno.lahansawah.nganjuk.jan2013

EKOSISTEM SWAH Dalam usaha budidaya padi harus diketahui faktor-faktor yang mempengaruhi pertumbuhan tanaman secara ekologi, baik faktor biotik dan abiotik di lingkungan tumbuh tanaman tersebut. Pertanaman padi sawah adalah monokultur, selain itu terdapat beberapa flora dan fauna di sekitar pertanaman yang akan mempengaruhi pertumbuhan tanaman padi. Organisme yang ada di sekitar tanaman padi adalah mikrofauna dalam tanah, mesofauna, makrofauna dan vegetasi (gulma) yang ada di sekitar persawahan. Lahan sawah ditanami padi monokultur, berbagai jenis pohon tumbuh di sepanjang pematang Foto: smno.lahansawah.madiun.jan2013

Lahan sawah perlu diperhatikan secara khusus dalam penatagunaan lahan.
BUDIDAYA PADI SAWAH Sawah merupakan suatu sistem budidaya tanaman yang khas dilihat dari sudut kekhususan pertanaman yaitu padi, penyiapan tanah, pengelolaan air dan dampaknya atas lingkungan. Lahan sawah perlu diperhatikan secara khusus dalam penatagunaan lahan. Meskipun di lahan sawah dapat diadakan pergiliran berbagai tanaman, namun pertanaman pokok selalu padi. Jadi, kajian tentang sawah tentu berkaitan dengan produksi padi dan beras. PADI SAWAH Teknik bercocok tanam yang baik sangat diperlukan untuk mendapatkan hasil yang sesuai dengan harapan. Hal ini harus dimulai dari awal, yaitu sejak dilakukan persemaian sampai tanaman itu bisa dipanen. Dalam proses pertumbuhan tanaman hingga berbuah ini harus dipelihara yang baik, terutama harus diusahakan agar tanaman terhindar dari serangan hama dan penyakit yang sering kali menurunkan produksi. Tanaman yang sehat ialah tanaman yang tidak terserang oleh hama dan penyakit, tidak mengalami defisiensi hara, baik unsur hara yang diperlukan dalam jumlah besar maupun dalam jumlah kecil. Sedangkan tanaman subur ialah tanaman yang pertumbuhan clan perkembangannya tidak terhambat, entah oleh kondisi biji atau kondisi lingkungan.

Interaksi antara sistem sosial dengan agroekosistem setelah terjadinya revolusi industri
Setelah revolusi industri, pertanian mengalami perubahan dnegan digunakannya mesin-mesin untuk menggantikan tenaga kerja manusia dan hewan untuk mengolah tanah dan panen tanaman. Starting with mechanization, the chain of effects can be traced. Machines gave farmers the ability to cultivate larger areas of land. Farm sizes increased dramatically because mechanized agriculture is more efficient on a larger scale (economy of scale). These initial changes in the social system and the ecosystem set in motion a series of changes through interconnected positive feedback loops in the ecosystem and social system Diunduh dari Sumber:

Koevolusi dan Ko-adaptasi Sistem Sosial Manusia dan Ekosistem
Interaction, coevolution and coadaptation of the human social system with the ecosystem Source: Adapted from Rambo, A and Sajise, T (1985) An Introduction to Human Ecology Research on Agricultural Systems in Southeast Asia, University of the Philippines, Los Banos, Philippines Diunduh dari Sumber:

Budidaya Padi Sawah Model SRI
Budidaya padi sawah (Ing. paddy atau paddy field), diduga dimulai dari daerah lembah Sungai Yangtse di Tiongkok. Budidaya padi lahan kering, dikenal manusia lebih dahulu daripada budidaya padi sawah. Budidaya padi lahan rawa, dilakukan di beberapa tempat di Pulau Kalimantan. Budidaya gogo rancah atau disingkat gora, yang merupakan modifikasi dari budidaya lahan kering. Sistem ini sukses diterapkan di Pulau Lombok, yang hanya memiliki musim hujan singkat. Budidaya Padi Sawah Model SRI SRI adalah salah satu jawaban dari krisis pangan yang dihadapi Indonesia. Akan tetapi berbeda dengan metode penanaman padi yan lain, SRI Indonesia dipelopori oleh seorang engineer. Ternyata SRI lebih bisa dimengerti oleh mereka yang memahami engineering walaupun tidak menutup kemungkinan adanya pendekatan lain yang dapat menjelaskan fenomena SRI. Apa Itu SRI ? SRI merupakan singkatan dari System of Rice Intensification, suatu sistem pertanian yang berdasarkan pada prinsip Process Intensification (PI) dan Production on Demand (POD). SRI mengandalkan optimasi untuk mencapai delapan tujuan PI, yaitu cheaper process (proses lebih murah), smaller equipment (bahan lebih sedikit), safer process (proses yang lebih aman), less energy consumption (konsumsi energi/tenaga yang lebih sedikit), shorter time to market (waktu antara produksi dan pemasaran yang lebih singkat), less waste or byproduct (sisa produksi yang lebih sedikit), more productivity (produktifitas lebih besar), and better image (memberi kesan lebih baik).

Penanganan bibit padi secara seksama.
Teknologi budidaya Bercocok tanam padi mencakup persemaian, pemindahan atau penanaman, pemeliharaan (termasuk pengairan, penyiangan, perlindungan tanaman, serta pemupukan), dan panen. Aspek lain yang penting namun bukan termasuk dalam rangkaian bercocok tanam padi adalah pemilihan kultivar, pemrosesan gabah dan penyimpanan beras. Penanganan bibit padi secara seksama. Hal ini terdiri atas, pemilihan bibit unggul, penanaman bibit dalam usia muda (kurang dari 10 hari setelah penyemaian), penanaman satu bibit per titik tanam, penanaman dangkal (akar tidak dibenamkan dan ditanam horizontal), dan dalam jarak tanam yang cukup lebar. Bagi yang telah terbiasa menanam padi secara konvensional, pola penanganan bibit ini akan dirasakan sangat berbeda. Hal ini karena metode konvensional memakai bibit yang tua (lebih dari 15 hari sesudah penyemaian), ditanam sekitar 5-10 bahkan lebih bibit per titik tanam, ditanam dengan cara dibenamkan akarnya, dan jarak tanamnya rapat.

BUDIDAYA PADI SECARA INTENSIF ( SYSTEM OF RICE INTENSIFICATION)
S R I ( SYSTEM OF RICE INTENSIFICATION) Suatu cara budidaya tanaman padi yang efesien dengan proses manajemen sistem perakaran yang berbasis pada pengelolaan air, tanah, dan tanaman SRI berasal dari Madagascar dikembangkan sejak sekitar 1980-an oleh Fr. Henri de Laulanié, SJ (biarawan asal Perancis) dan berkembang ke sekitar 24 negara sejak sekitar 1993

BUDIDAYA PADI SECARA INTENSIF PERMASALAHAN BUDIDAYA TANAMAN PADI
Penurunan kesehatan dan kesuburan tanah Kecenderungan potensi padi untuk berproduksi lebih tinggi mandeg Penggunaan unsur kimia anorganik dan pestisida sintesis meningkat Perilaku petani sudah jauh dari kearifan dalam memanfaatkan potensi lokal Petani bekerja di lahan sawah Many people from the district of Rembang, Java, work in the labour intensive rice paddy industry. The production of rice is a commercial industry and provides income for many families. Diunduh dari Sumber: …..30/10/2012

BUDIDAYA PADI SECARA INTENSIF DASAR PEMIKIRAN METODE SRI
Tanaman Padi mempunyai potensi yang besar untuk menghasilkan produksi yang banyak Produksi yang optimal dapat dicapai dengan terpenuhinya kondisi yang optimal Produksi optimal dapat dicapai melalui proses pengelolaan tanah, tanaman dan air serta unsur agroekosistemnya Ada kecenderungan penurunan produksi Padi bukan tanaman air, tetapi padi tanaman yang membutuhkan banyak air Pada kondisi tanah tidak tergenang, akar tanaman tumbuh subur dan besar, sehingga dapat menyerap hara yang banyak, serta mendorong tumbuhnya ANAKAN yang optimal.

BUDIDAYA PADI SECARA INTENSIF
PENYEBAB TERJADINYA PENURUNAN PRODUKSI PADI Penurunan kesuburan tanah akibat penggunaan pupuk secara intensif dan terus-menerus Mikroba dalam tanah tidak berfungsi secara optimal Aliran energi dari bawah ke atas permukaan tanah tidak seimbang Suplai hara-tersedia dalam tanah sangat kurang Tanaman menunggu suplai hara dari luar tanah, berupa pupuk sintesis Penggunaan pupuk dan pestisida sintesis yang berlebihan mengakibatkan rantai makanan dalam ekosistem sawah menjadi terputus Musuh Alami hanya menunggu makanan dari keberadaan hama Jenjang hirerkis Musuh Alami lebih tinggi maka hama akan berkembang lebih pesat .

BUDIDAYA PADI SECARA INTENSIF CARA PANDANG KURANG ARIF
Orang beranggapan di sawah hanya ada tanaman dan hama Untuk memenangkan persaingan hama harus dibunuh Pestisida yang berkuasa untuk memusnahkan hama Pestisida tidak bisa mengentaskan masalah karena hama Hama menjadi kebal Terjadi peledakan gangguan hama dan penyakit Pencemaran lingkungan Terbunuhnya jasad non sasaran Pengurangan keaneka-ragaman hayati Gangguan terhadap kesehatan manusia .

SRI Di Indonesia antara lain oleh Pak Engkus Kuswara dan Pak Alik Sutaryat (Tahun 1999). Hal-hal yang diterapkan adalah : • Tanam Tunggal Dan Dangkal • Umur Semai Kurang 15 Hari • Penanaman cepat kurang 15 Menit • Pupuk Organik SRI merupakan singkatan dari System of Rice Intensification, suatu sistem pertanian yang berdasarkan pada prinsip Process Intensification (PI) dan Production on Demand (POD). SRI mengandalkan optimasi untuk mencapai delapan tujuan PI, yaitu : Cheaper process (proses lebih murah), Smaller equipment (bahan lebih sedikit), Safer process (proses yang lebih aman), Less energy consumption (konsumsi energi/tenaga yang lebih sedikit), Shorter time to market (waktu antara produksi dan pemasaran yang lebih singkat), Less waste or byproduct (sisa produksi yang lebih sedikit), More productivity (produktifitas lebih besar), and Better image (memberi kesan lebih baik).

METODE SRI : Tanaman Hemat Air (Max 2 Cm = Macak-macak dan juga ada periode pengeringan sampai tanah pecah-pecah) Hemat Biaya (butuh bibit 5 Kg/Ha, Tidak butuh biaya Pencabutan, Pemindahan, Irit tenaga tanam, dll) Hemat Waktu (bibit ditanam muda HSS dengan jarak tanam lebar dan Panen lebih awal sekitar 10 – 14 hari) Produksi Bisa Mencapai Ton/Ha. METODE SRI Penanganan bibit padi secara seksama. Hal ini terdiri atas, pemilihan bibit unggul, penanaman bibit dalam usia muda (kurang dari 10 hari setelah penyemaian), penanaman satu bibit per titik tanam, penanaman dangkal (akar tidak dibenamkan dan ditanam horizontal), dan dalam jarak tanam yang cukup lebar. Bagi yang telah terbiasa menanam padi secara konvensional, pola penanganan bibit ini akan dirasakan sangat berbeda. Hal ini karena metode konvensional memakai bibit yang tua (lebih dari 15 hari sesudah penyemaian), ditanam sekitar 5-10 bahkan lebih bibit per titik tanam, ditanam dengan cara dibenamkan akarnya, dan jarak tanamnya rapat.

PENGARUH PENGGENANGAN AIR TERHADAP PERTUMBUHAN PADI
Merangsang pertumbuhan memanjang tanaman, menghasilkan lebih banyak jerami Menghambat pertumbuhan anakan/tunas Tanaman kurang dapat mengambil unsur hara yang dibutuhkan Penggenangan yang terlalu dalam dan lama dapat merubah sifat-sifat kimia tanah sawah, antara lain : kandungan O2 yang sedikit, kandungan CO2 yang berlebihan, terjadi akumulasi H2S, yang dapat meracuni tanaman sehingga tanaman menjadi kerdil. METODE SRI Penyiapan lahan tanam. Penyiapan lahan tanam untuk metode SRI berbeda dari metode konvensional terutama dalam hal penggunaan air dan pupuk sintetis (untuk kemudian disebut pupuk). SRI hanya menggunakan air sampai keadaan tanahnya sedikit terlihat basah oleh air (macak-macak) dan tidak adanya penggunaan pupuk karena SRI menggunakan kompos. Sangat berbeda dengan metode konvensional yang menggunakan air sampai pada tahap tanahnya menjadi tergenang oleh air serta pemupukan minimal dua kali dalam satu periode tanam.

PRINSIP SRI METODE SRI Pengolahan tanah dan pemupukan kompos organik
Benih bermutu dan ditanam muda Benih ditanam tunggal dan langsung Jarak tanam Lebar Pemupukan tidak dengan pupuk sintesis Pengelolaan air yang macak-macak dan bersamaan dengan penyiangan PHT tidak memakai pestisida sintesis METODE SRI Keterlibatan mikro-organisme lokal (MOL) dan kompos sebagai ’tim sukses’ dalam pencapaian produktivitas yang berlipat ganda. Dalam hal ini peran kompos sering disalah-artikan sebagai pengganti dari pupuk. Hal ini salah, karena peran kompos lebih kompleks daripada peran pupuk. Peran kompos, selain sebagai penyuplai nutrisi juga berperan sebagai komponen bioreaktor yang bertugas menjaga proses tumbuh padi secara optimal. Konsep bioreaktor adalah kunci sukses dari SRI. Bioreaktor yang dibangun oleh kompos, mikrooganisme lokal, struktur padi, dan tanah menjamin bahwa padi selama proses pertumbuhan dari bibit sampai padi dewasa tidak mengalami hambatan. Fungsi bioreaktor sangat kompleks, antara lain adalah penyuplai nutrisi sesuai POD melalui mekanisme eksudat, kontrol mikroba sesuai kebutuhan padi, menjaga stabilitas kondisi tanah menuju kondisi yang ideal bagi pertumbuhan padi, bahkan kontrol terhadap penyakit yang dapat menyerang padi.

UJI BENIH BERMUTU DENGAN LARUTAN GARAM
Caranya : Siapkan ember atau panci atau wadah lain beriisi air Masukan garam aduk-aduk sampai larut, Masukan telur ayam mentah kedalam larutan garam tersebut, bila telur masih tenggelam maka perlu penambahan garam. Pemberian garam dianggap cukup apabila telur sudah mengapung. Masukan benih yang sudah disiapkan kedalam larutan tersebut. Benih yang tenggelam yang digunakan sebagai benih yang akan ditanam. PENYIAPAN BENIH Benih dapat diseleksi dengan bantuan penggunaan air garam dan telur ayam/itik/bebek. Telur yang bagus umumnya dalam air akan tenggelam, namun bila pada air ini diberi garam yang cukup dan diaduk maka telur yang bagus itu akan mengapung. Bila telur belum juga mengapung maka tambahkan lagi garamnya sampai telur ini mengapung karena berat jenisnya (BJ) menjadi lebih rendah daripada air garam. Air garam yang sudah mampu mengapungkan telur ini dapat digunakan untuk seleksi benih

PERENDAMAN DAN PEMERAMAN BENIH
BENIH DIRENDAM, Setelah diuji, benih direndam dengan mempergunakan air bersih dengan tujuan mempercepat perkecambahan selama 24 – 48 jam. BENIH DIPERAM, Benih yang telah direndam kemudian diangkat ke dalam tempat tertentu yang telah dilapisi dengan daun pisang dengan tujuan untuk memberikan udara masuk / penganginan / ngamut selama 24 jam. Benih yang baik kemudian dicuci dengan bersih sampai rasa asinnya hilang dari benih tersebut, juga akan lebih baik dicuci menggunakan wadah yang berlubang dan pada air yang mengalir untuk meyakinkan benih benar-benar akan terbebas dari garam; Benih yang sudah bebas dari garam direndam dalam air biasa selama sekitar 24 jam; Setelah benih direndam, kemudian lakukan pemeraman selama sekitar 36 jam yaitu benih di bungkus dengan karung goni atau kain yang basah. Penyimpanan benih yang dibungkus kain basah ini akan lebih baik ditempat yang hangat misalnya di dapur asalkan kainnya tetap dijaga basah dan lembab; Setelah berkecambah atau muncul akar pendek, benih siap disemai atau ditebar.

CARA MEMBUAT PERSEMAIAN
Campurkan Tanah dan kompos 1 : 1 Masukan campuran tanah dan kompos ke dalam baki atau pipiti yang dilapisi daun pisang Taburkan benih ke dalam nampan Tutup dengan jerami atau kompos Persemaian padi dengan Menggunakan Pupuk HOSC sebagai pupuk Semai , menunjukkan pertumbuhan yang bagus dan perkembangan akar yang sempurna pada usia 9 hari, dan pada usia 13 hari benih padi

Bibit ditanam dangkal 1 – 1,5 cm dengan perakaran seperti huruf L.
CARA PENANAMAN BENIH Tanam benih berusia muda antara hari (maksimal berdaun 2), usahakan di bawah 8 hari setelah semai. Tanam hanya 1 (satu) benih per lubang dengan jarak tanam 30x30 cm atau 35x35 cm Bibit ditanam dangkal 1 – 1,5 cm dengan perakaran seperti huruf L. Pindah tanam (transplanting) harus segera (kurang dari 15 menit) secara hati-hati Petak sawah tidak selalu tergenang, kondisi air hanya ‘macak-macak’ (1-2 cm) dan pada periode tertentu harus dikeringkan sampai retak (intermittent irrigation) Penyiangan dilakukan lebih awal pada 10 hst diulang 3 s/d 4 kali dengan interval waktu setiap 10 hari ( mengunkan tenaga manusia/lalandak ) . PENYEMAIAN Penyemaian dapat dilakukan di sawah, di ladang atau dalam wadah seperti kotak plastik atau besek/pipiti yang diberi alas plastik/daun pisang dan berada di area terbuka yang mendapatkan sinar matahari. Tanah untuk penyemaian tidak menggunakan tanah sawah tetapi menggunakan tanah darat yang gembur dicampur dengan kompos dengan perbandingan tanah:kompos sebaiknya minimal 2:1 dan akan lebih baik bila 1:1, dapat juga ditambahkan pada campuran ini abu bakar agar medianya semakin gembur sehingga nantinya benih semakin mudah diambil dari penyemaian untuk menghindari putusnya akar. Luas area yang diperlukan untuk penyemaian minimal adalah sekitar 20 m2 untuk setiap 5 kg benih, sehingga bila penyemaian dilakukan pada wadah dapat dihitung jumlah wadah yang diperlukan menyesuaikan dengan ukuran masing-masing wadah dan tentunya akan lebih baik lagi bila tempat penyemaiannya lebih luas untuk pertumbuhan benih yang lebih sehat.

KETERBATASAN S R I Membutuhkan tenaga kerja lebih banyak (pada awalnya) Perlu drainase untuk membuang kelebihan air Lebih banyak waktu untuk untuk mengatur pengairan Lebih banyak waktu dan tenaga kerja untuk penyiangan Pembuatan kompos PRINSIP PENANAMAN SRI Penanaman Bibit Muda; Penanaman Bibit Tunggal dan Jarak Antar Tanaman yang Lebar; Penanaman Segera Untuk Menghindari Trauma Pada Bibit; Penanaman Dangkal; Lahan Sawah Tidak Terus Menerus Direndam Air; Penyiangan Mekanis; Menjaga Keseimbangan Biologi Tanah.

Hama-hama penting tanaman padi
Penggerek batang padi putih ("sundep", Scirpophaga innotata) Penggerek batang padi kuning (S. incertulas) Wereng batang punggung putih (Sogatella furcifera) Wereng coklat (Nilaparvata lugens) Wereng hijau (Nephotettix impicticeps) Lembing hijau (Nezara viridula) Walang sangit (Leptocorisa oratorius) Ganjur (Pachydiplosis oryzae) Lalat bibit (Arterigona exigua) Ulat tentara/Ulat grayak (Spodoptera litura dan S. exigua) Tikus sawah (Rattus argentiventer) Sistem pertanian sawah terpadu (Sumber: tani-organik.blogspot.com/2008/0...sri.html)

Penyakit-penyakit penting
Blas (Pyricularia oryzae, P. grisea) Hawar daun bakteri ("kresek", Xanthomonas oryzae pv. oryzae) Bercak coklat daun (Helmintosporium oryzae). Garis coklat daun (Cercospora oryzae) Busuk pelepah daun (Rhizoctonia sp) Penyakit fusarium (Fusarium moniliforme) Penyakit noda (Ustilaginoidea virens) Hawar daun (Xanthomonas campestris) Penyakit bakteri daun bergaris (Translucens) Penyakit kerdil (Nilaparvata lugens) Penyakit tungro (Nephotettix impicticeps) James Stordahl Extension Educator, Clearwater and Polk Counties Plants need three factors for disease to develop. The host plant must be susceptible, the pathogen must be present (usually in the soil), and the environmental conditions must be right. This typically involves wet leaves over some period of time. Diunduh dari Sumber: …..30/10/2012

HUBUNGAN AIR-TANAH-TANAMAN
Unsur hara & daya simpan hara Bahan Organik Tanah Makro-fauna Tanah Mikroba Tanah

PENGELOLAAN AIR PADA TANAH SAWAH
Produksi padi sawah akan menurun jika tanaman padi menderita cekaman air (water stress). Gejala umum akibat kekurangan air antara lain daun padi menggulung, daun terbakar (leaf scorching), anakan padi berkurang, tanaman kerdil, pembungaan tertunda, dan biji hampa. Tanaman padi membutuhkan air yang volumenya berbeda untuk setiap fase pertumbuhannya. Variasi kebutuhan air tergantung juga pada varietas padi dan sistem pengelolaan lahan sawah. Pengaturan air untuk sistem mina-padi berbeda dengan sistem sawah tanpa ikan. Pengelolaan air di lahan sawah tidak hanya menyangkut sistem irigasi, tetapi juga sistem drainase pada saat tertentu dibutuhkan, baik untuk mengurangi kuantitas air maupun untuk mengganti air yang lama dengan air irigasi baru sehingga memberikan peluang terjadinya sirkulasi oksigen dan hara.

Di Indonesia, sawah sering dikategorikan menjadi tiga yaitu
SAWAH IRIGASI Di Indonesia, sawah sering dikategorikan menjadi tiga yaitu sawah beririgasi; sawah tadah hujan; dan sawah rawa (lebak dan pasang surut). Sistem pengelolaan air pada ketiga macam sawah tersebut sangat berbeda, karena perbedaan kondisi hidrologi dan kebutuhan air. Teknik pengelolaan air lahan sawah didasarkan pada kebutuhan air untuk tanaman (baik padi maupun palawija) dan sistem pengelolaan lahan sawah. KEBUTUHAN AIR IRIGASI Kebutuhan air tanaman didefinisikan sebagai jumlah air yang dibutuhkan oleh tanaman pada suatu periode untuk dapat tumbuh dan produksi secara normal. Kebutuhan air nyata untuk areal usaha pertanian meliputi evapotranspirasi (ET), sejumlah air yang dibutuhkan untuk pengoperasian secara khusus seperti penyiapan lahan dan penggantian air, serta kehilangan selama pemakaian. Sehingga kebutuhan air dapat dirumuskan sebagai berikut (Sudjarwadi 1990): KAI = ET + KA + KK Dimana: KAI = Kebutuhan Air Irigasi; ET = Evapotranspirasi; KA = Kehilangan air; KK = Kebutuhan Khusus. Diunduh dari sumber: /10/2012

Hidrologi lahan sawah Pengetahuan tentang hidrologi lahan sawah sangat diperlukan dalam merancang strategi pengelolaan air. Karakteristik hidrologi lahan sawah sangat ditentukan oleh kondisi biofisik lahan. Hidrologi sawah beririgasi berbeda dengan sawah tadah hujan maupun sawah rawa. Oleh karena itu strategi pengelolaan air pada lahan sawah beririgasi akan berbeda dengan pada lahan sawah tadah hujan maupun sawah rawa. Types of Response to Water Scarcity Sumber: Irrigation Management in Rice-Based Cropping Systems: Issues and Challenges in Southeast Asia . Randolph Barker and Francois Molle. Diunduh dari sumber: 30/10/2012

NERACA AIR LAHAN SAWAH Masukan air ke lahan padi sawah diperlukan untuk menggantikan kehilangan air akibat rembesan-seepage, perkolasi, evaporasi dan transpirasi. Seepage is the lateral subsurface flow of water and percolation is the down flow of water below the root zone. Typical combined values for seepage and percolation vary from 1-5 mm d-1 in heavy clay soils to mm d-1 in sandy and sandy loam soils. Evaporation occurs from the ponded water layer and transpiration is water loss from the leaves of the plants. Typical combined evapotranspiration rates of rice fields are 4-5 mm d-1 in the wet season and 6-7 mm d-1 in the dry season, but can be as high as mm d-1 in subtropical regions before the onset of the monsoon. Total seasonal water input to rice fields (rainfall plus irrigation) varies from as little as 400 mm in heavy clay soils with shallow groundwater tables to more than 2000 mm in coarse-textured (sandy or loamy) soils with deep groundwater tables. Around mm is a typical value for irrigated rice in Asia. Outflows of water by seepage and percolation account for about 25-50% of all water inputs in heavy soils with shallow water tables of cm depth, and for 50-85% in coarse-textured soils with deep water tables of 150 cm depth or more. Diunduh dari sumber: ………. 30/10/2012

KARAKTERISTIK HIDROLOGI LAHAN SAWAH
Lahan sawah Pluvial Sumber air berasal dari air hujan Kelebihan air hilang melalui perkolasi dan aliran permukaan Terdapat di daerah landai sampai lereng curam Air tanah dalam, drainase baik, tidak ada gejala jenuh air dalam profil tanah Padi ditanam sebagai padi gogo . Hydrological processes in a paddy field. (a) Hydrologic Characteristics of a paddy field. (b) Outline of runoff simulation model in paddies. Simulations of storm hydrographs in a mixed-landuse watershed using a modified TR-20 model T.I. Jang, H.K. Kim, S.J. Im, S.W. Park. Agricultural Water Management. Volume 97, Issue 2, February 2010, Pages 201–207.

KARAKTERISTIK HIDROLOGI LAHAN SAWAH
Lahan sawah Phreatik Sumber air berasal dari air hujan dan air tanah Air tanah (phreatic) dangkal, paling tidak pada waktu musim tanam Kelebihan air hilang melalui aliran permukaan Tidak pernah tergenang lebih dari beberapa jam Dalam profil tanah ada gejala jenuh air (gley motting) Bila tanpa perataan (leveling) dan pembuatan pematang, akan lebih baik ditanami padi gogo Bila dengan perataan dan pembuatan pematang dapat dikembangkan untuk padi sawah . Schematics of water balance components in a paddy field. Model development for nutrient loading from paddy rice fields Sang-Ok Chung, Hyeon-Soo Kim, Jin Soo Kim. Agricultural Water Management. Volume 62, Issue 1, 19 August 2003, Pages 1–17

Karakteristik hidrologi lahan sawah
Lahan sawah fluxial Sumber air seluruhnya atau sebagian berasal dari aliran permukaan, air sungai dan air hujan langsung Dalam keadaan alami tergenang air selama beberapa bulan yaitu selama padi ditanam Terdapat di daerah lembah, dataran aluvial sungai dan sebagainya Drainase permukaan dan drainase dalam (perkolasi) lambat sehingga genangan air mudah terjadi Padi ditanam sebagai padi sawah . Schematic diagram of a paddy field. (hmin, hmax and Hp denote the three critical depths; Ecan, Epot and Es denote the three kinds of evaporation from the free water in canopies, the water body surface and the soil water respectively; Ep denotes the crop transpiration. Development and test of SWAT for modeling hydrological processes in irrigation districts with paddy rice Xianhong Xie, Yuanlai Cui. Journal of Hydrology. Volume 396, Issues 1–2, 5 January 2011, Pages 61–71.

MANAJEMEN AIR YANG BAGUS UNTUK LAHAN SAWAH
Beberapa prinsip Manajemen Air yang bagus di lahan sawah PERATAAN TANAH A well-leveled field is a prerequisite for good water management. When a field is not level, water may stagnate in the depressions whereas higher parts may fall dry. This results in uneven crop emergence, uneven early growth, uneven fertilizer distribution, and weed problems. See the fact sheets on land leveling for more information . SALURAN AIR TERBUKA In many paddy fields, water flows from one field to another through breaches in the bunds. Under such conditions, water in an individual field can not be controlled and field-specific water management is not possible - construction of channels to convey water to and from each field, or group of fields, greatly improves the irrigation and drainage of water. PENGOLAHAN TANAH Wet land preparation can consume up to a third of the total water used in paddy rice. In large-scale irrigation systems, synchronizing operations and minimizing the duration of the land preparation period can reduce water use. Large amounts of water can be lost during soaking prior to puddling when large and deep cracks are present. A shallow tillage to fill the cracks before soaking can greatly reduce this water loss. After soaking, thorough puddling results in a compacted plow sole that reduces water losses by percolation. The efficacy of puddling depends on soil properties. Puddling may not be effective in coarse soils, whereas it is very efficient in clay soils that form cracks during the fallow period. Puddling may not be necessary in heavy clay soils with limited internal drainage. In such soils, direct dry seeding on land that is tilled in a dry state is possible with minimal percolation losses. Diunduh dari sumber: ………. 30/10/2012

PEMATANG SAWAH KEDALAMAN GENANGAN AIR
MANAJEMEN AIR YANG BAGUS UNTUK LAHAN SAWAH Beberapa prinsip Manajemen Air yang bagus di lahan sawah PEMATANG SAWAH Good bunds are a prerequisite to limit water losses by seepage and under-bund flows. Bunds should be well compacted and any cracks or rat holes should be plastered with mud at the beginning of the crop season. Also, check for, and repair new rat holes, cracks, and porosity caused by earth worms throughout the growing season. Lembaran plastik dapat dipakai untuk memperbaiki pematang, terutama bagian-bagian pematang yang “rembes” (bocor) air. KEDALAMAN GENANGAN AIR Menjaga kedalaman genangan air sekitar 5 cm dapat meminimumkan kehilangan air melalui rembesan- seepage dan perkolasi. Diunduh dari sumber: ………. 30/10/2012

Good water management in lowland rice focuses on practices that conserve water (by eliminating the unproductive water flows of seepage, percolation, and evaporation) while ensuring sufficient water for the crop. Water management practices are given for the different periods of the crop cycle from pre-planting activities to the ripening stage. It is assumed that farmers have access to sufficient irrigation to maintain flooded conditions. Water-saving technologies for conditions of insufficient water are described in subsequent paragraphs. Pra- tanam Jumlah air yg diperlukan untuk mengolah tanah pada lahan sawah dapat sebesar mm, tetapi juga dapat mencapai hingga 900 mm dalam sistem irigasi sekala besar dan periode penyiapan lahan yang cukup panjang. Various options exist to minimize the amount of water used in the pre-planting period. Land preparation lays the foundation for the whole cropping season and it is important in any situation to “get the basics right” for good water management afterwards. Especially important for good water management are field channels, land leveling, and tillage operations (puddling, bund preparation and maintenance). Diunduh dari sumber: /10/2012

Saluran lapangan untuk mengelola air
MANAJEMEN AIR YANG BAGUS UNTUK LAHAN SAWAH Saluran lapangan untuk mengelola air Dalam berbagai sistem irigasi, tidak ada saluran air terbuka (saluran tersier , kuarter atau saluran drainage) dan air mengalir dari satu petak-lahan ke petakan lainnya mellaui lubang-lubang pada pematang. Sistem seperti ini disebut irigasi “plot-to-plot”. The amount of water flowing in and out of a rice field can not be controlled and field-specific water management is not possible. This means that farmers may not be able to drain their fields before harvest because water keeps flowing in from other fields. Also, they may not be able to have water flowing in if upstream farmers retain water in their fields or let their fields dry out to prepare for harvest. Moreover, a number of technologies to cope with water scarcity require good water control for individual fields. Finally, the water that continuously flows through the rice fields may remove valuable (fertilizer) nutrients. Constructing separate channels to convey water to (irrigation) and from (drainage) each field greatly improves the individual control of water, and is the recommended practice in any type of irrigation system. Alternatively, if field channels can not be constructed for individual fields, they should be constructed to serve a limited number of fields together. Diunduh dari sumber: /10/2012

PROSES PELUMPURAN A rice field can be compared with a bath tub: the material of a bath tub is impregnable and it holds water well – however, you only need to have one hole (by removing the plug) and the water runs out immediately. Rice fields just need a few rat holes or leaky spots and they will rapidly loose water by seepage and percolation. Thorough puddling results in a good compacted plow sole that reduces the percolation rates throughout the crop growing period. The efficacy of puddling in reducing percolation depends greatly on soil properties. Puddling may not be effective in coarse soils, which do not have enough fine clay particles to migrate downward and fill up the cracks and pores in the plow sole. On the other hand, puddling is very efficient in clay soils that form cracks during the fallow period that penetrate the plow pan. Although puddling reduces percolation rates of the soil, the action of puddling itself consumes water, and there is a trade-off between the amount of water used for puddling and the amount of water “saved” during the crop growth period by reduced percolation rates. Pelumpuran mungkin tidak diperlukan pada tanah-tanah liat-berat yang permeabilitasnya rendah atau drainage internalnya sangat terbatas. Pada tanah-tanah seperti ini, tanam benih langsung di lahan yg tidak dilumpurkan tetapi diolah kering , sangat dimungkinkan dengan kehilangan perkolasi minimum. Diunduh dari sumber: /10/2012

PENYIAPAN DAN PEMELIHARAAN PEMATANG Good bunds are a prerequisite to limit water losses by seepage and underbund flows. To limit seepage losses, bunds should be well compacted and any cracks or rat holes should be plastered with mud at the beginning of the crop season. Make bunds high enough (at least 20 cm) to avoid overbund flow during heavy rainfall. Small levees of 5-10 cm height in the bunds can be used to keep the ponded water depth at that height. If more water needs to be stored, it is relatively simple to close these levees. Researchers have used plastic sheets in bunds in field experiments to reduce seepage losses. Although such measures are probably financially not attractive to farmers, the author has come upon a farmer in the Mekong delta in Vietnam who used old plastic sheets to block seepage through very leaky parts of his bunds. Liang tikus harus dibuntu Diunduh dari sumber: /10/2012

MANAJEMEN AIR UNTUK LAHAN SAWAH BIDANG OLAH IRIGASI DIBATASI PEMATANG
Most lowland rice is established by transplanting rice plants from a seed bed into the main field. In large-scale irrigation systems, seed beds are often found in corners of individual farmers’ fields scattered throughout the area. If there are no field channels to separately irrigate the seed beds, the whole field is flooded while the rice plants grow in the seed bed. All water losses from the main field through evaporation, seepage, and percolation, are a wasteful loss as no crop grows yet in the field. One remedy is to construct field channels that bring water to the seed beds only so that the main field only needs to be soaked and puddled a few days before transplanting (3-4 days). Seed beds are best located close to the main canals so that little water is lost by transporting it over long distances through field channels. Community seed beds may be an option to concentrate the raising of seedlings in one place to use the irrigation water most efficiently. In some areas, private companies produce seedlings that farmers can purchase so they save their own irrigation water. Diunduh dari sumber: /10/2012

FASE PERTUMBUHAN AWAL VEGETATIF After crop establishment, continuous ponding of water generally provides the best growth environment for rice and will result in the highest yields. Flooding also helps suppress weed growth, improves the efficiency of use of nitrogen and, in some environments, helps protect the crop from fluctuations in temperatures. After transplanting, water levels should be around 3 cm initially, and gradually increase to 5-10 cm with increasing plant height. With direct wet seeding, the soil should be kept just at saturation from sowing to some 10 days after emergence, and then the depth of ponded water should gradually increase with increasing plant height. With direct dry seeding, the soil should be moist but not saturated from sowing till emergence, else the seeds may rot in the soil. After sowing, apply a flush irrigation if there is no rainfall to wet the soil. Saturate the soil when plants have developed 3 leaves, and gradually increase the depth of ponded water with increasing plant height. Under certain conditions, allowing the soil to dry out for a few days before reflooding can be beneficial to crop growth. In certain soils high in organic matter, toxic substances can be formed during flooding that can be removed through intermittent soil drying. Intermittent soil drying promotes root growth which can help plants resist lodging better in case of strong winds later in the season. Intermittent soil drying can also help control certain pests or diseases that require standing water for their spread or survival, such as golden apple snail. The farmers often practice a period of 7-10 days “mid-season drainage” (during which the soil is left to dry out) during the active tillering stage. This practice should reduce the number of excess and nonproductive tillers, but these benefits are not always found. Intermittent soil drying is also used in the System of Rice Intensification (SRI) and is suggested to lead to improved soil health. Other research, however, shows that nonflooded soil promotes the occurrence of certain soils pests such as nematodes. Diunduh dari sumber: /10/2012

FASE PERTUMBUHAN REPRODUKTIF Lowland rice is extremely sensitive to water shortage at the flowering stage, and drought effects occur when soil water contents drop below saturation. Drought at flowering results in increase spikelet sterility, decreased percentage filled spikelets, and, therefore, decreased number of grains per panicle and decreased yields. Keep the water level in the fields at 5 cm at all times during this stage. Diunduh dari sumber: /10/2012

FASE PEMASAKAN This period does not necessarily require flooding. Soil that is 80–90% saturated is sufficient. However, for easy operations, keeping the fields flooded may still be the simplest management approach. Draining the fields some days before the expected harvest date hastens maturity and grain ripening, prevents excessive nitrogen uptake, and makes the land better accessible (because it is dryer) for harvest operations. Diunduh dari sumber: /10/2012

PEMBASAHAN DAN PENGERINGAN YG BERGANTIAN (AWD) In alternate wetting and drying (AWD), irrigation water is applied to obtain flooded conditions after a certain number of days have passed after the disappearance of ponded water. AWD is also called ‘intermittent irrigation’ or ‘controlled irrigation’. The number of days of nonflooded soil in AWD before irrigation is applied can vary from 1 day to more than 10 days. A practical way to implement AWD is to monitor the depth of the water table on the field using a simple perforated ‘field water tube’. After an irrigation application, the field water depth will gradually decrease in time. When the water level (as measured in the tube) is 15 cm below the surface of the soil, it is time to irrigate and flood the soil with a depth of around 5 cm. Around flowering, from 1 week before to one week after the peak of flowering, ponded water should be kept at 5 cm depth to avoid any water stress that would result in potentially severe yield loss. The threshold of 15 cm is called ‘Safe AWD” as this will not cause any yield decline since the roots of the rice plants will still be able to take up water from the saturated soil and the perched water in the rootzone. The field water tube helps farmers see this “hidden” source of water. In Safe AWD, water savings may be relatively small, in the order of 15%, but there is no yield penalty. After creating confidence that Safe AWD does not reduce yield, farmers may experiment by lowering the threshold level for irrigation to 20, 25, 30 cm, or even deeper. Some yield penalty may be acceptable when the price of water is high or when water is very scarce. Diunduh dari sumber: /10/2012

Irigasi Permukaan Irigasi Permukaan merupakan sistem irigasi yang menyadap air langsung di sungai melalui bangunan bendung maupun melalui bangunan pengambilan bebas (free intake) kemudian air irigasi dialirkan secara gravitasi melalui saluran sampai ke lahan pertanian. Dalam irigasi dikenal saluran primer, sekunder, dan tersier. Pengaturan air ini dilakukan dengan pintu air. Prosesnya adalah gravitasi, tanah yang tinggi akan mendapat air lebih dulu. Bangunan irigasi untuk menyalurkan air irigasi ke swah intensif di Kab. Jember

Sistem irigasi pertanian di Niigata
Irigasi Lokal Sistem ini air distribusikan dengan cara pipanisasi. Di sini juga berlaku gravitasi, di mana lahan yang tinggi mendapat air lebih dahulu. Namun air yang disebar hanya terbatas sekali atau secara lokal. Sistem irigasi pertanian di Niigata Dari pintu pengeluaran air tersebut dialirkan ke sawahnya melalui pipa yang berada di bawah permukaan sawahnya. Kalau di tanah air kita pada umumnya air dialirkan melalui permukaan sawah. Diunduh dari sumber: ………. 28/10/2012

Irigasi Tradisional dengan Ember Small-scale drip irrigation systems
Di sini diperlukan tenaga kerja secara perorangan yang banyak sekali. Di samping itu juga pemborosan tenaga kerja yang harus menenteng ember. Small-scale drip irrigation systems BUCKET SYSTEM The bucket system consists of two drip lines, each m long, and a 20-litre bucket for holding water. Each of the drip lines is connected to a filter to remove any particles that may clog the drip nozzles. The bucket is supported on a bucket stand, with the bottom of the bucket at least 1 m above the planting surface. One bucket system requires 2-4 buckets of water per day and can irrigate plants with a spacing of 30 cm between the rows. For crops such as onions or carrots, the number of plants can be as many as the bed can accommodate. A farmer growing for the market can usually recover this investment within the first crop season. Diunduh dari sumber: /10/2012

Irigasi Pasang-Surut di Sumatera, Kalimantan, dan Papua
Dengan memanfaatkan pasang-surut air di wilayah Sumatera, Kalimantan, dan Papua dikenal apa yang dinamakan Irigasi Pasang-Surat (Tidal Irrigation). Teknologi yang diterapkan di sini adalah: pemanfaatan lahan pertanian di dataran rendah dan daerah rawa-rawa, di mana air diperoleh dari sungai pasang-surut di mana pada waktu pasang air dimanfaatkan. Di sini dalam dua minggu diperoleh 4 sampai 5 waktu pada air pasang. LAHAN PASANG-SURUT Lahan pasang surut adalah lahan yang pada musim penghujan (bulan desember-mei) permukaan air pada sawah akan naik sehingga tidak dapat di tanami padi. Pada musim kemarau (bulan juli-september) air permukaan akan surut yang mana pada saat itu tanaman padi sawah baru dapat ditanam (pada lokasi yang berair). (LIPI Kalimantan, 1994) Combined drainage and irrigation system using tidal differences (source ESCAP 1978)

Irigasi Tanah Kering atau Irigasi Tetes
Di lahan kering, air sangat langka dan pemanfaatannya harus efisien. Jumlah air irigasi yang diberikan ditetapkan berdasarkan kebutuhan tanaman, kemampuan tanah memegang air, serta sarana irigasi yang tersedia. Ada beberapa sistem irigasi untuk tanah kering, yaitu: (1) irigasi tetes (drip irrigation), (2) irigasi curah (sprinkler irrigation), (3) irigasi saluran terbuka (open ditch irrigation), dan (4) irigasi bawah permukaan (subsurface irrigation). Untuk penggunaan air yang efisien, irigasi tetes [3] merupakan salah satu alternatif. Misal sistem irigasi tetes adalah pada tanaman cabai. DRIP IRRIGATION In drip irrigation, water flows through a filter into special drip pipes, with emitters located at different spacings. Water is discharged through the emitters directly into the soil near the plants through a special slow-release device. Diunduh dari sumber: /10/2012

TRANSPOR AIR: Tanah – Tanaman - Atmosfir
Air bergerak dari tanah, melalui akar, batang, daun, memasuki atmosfer Laju aliran air ini merupakan fungsi F (selisih potensial, resistensi) Potential unit name Corresponding value Water height (cm) 1 10 100 1000 15850 pF (-) 2 3 4.2 Bar (bar) 0.001 0.01 0.1 15.85 Pascal (Pa) 10000 Kilo Pascal (kPa) 1585 Mega Pascal (MPa) 0.0001 1.585

TEGANGAN AIR Potential air bernilai positif dalam kondisi “free liquid water” Potential dalam sistem tanah-tanaman-atmosfir bernilai negatif (dalam tanah sawah tergenang, potential air positif) Air bergerak dari potential tinggi (top of hill) menuju ke potential rendah (bottom of hill) Tegangan adalah – potential: air bergerak dari tegangan rendah menuju tegangan tinggi Rice plants take up water from the soil and transport it upward through the roots and stems and release it through the leaves and stems as vapor in the atmosphere (called transpiration). The movement of water through the plant is driven by differences in water potential: water flows from a high potential to a low potential (imagine free water flow over a sloping surface: water flows from the top, with a high potential, to the bottom, with a low potential). In the soil-plant-atmosphere system, the potential is high in the soil and low in the atmosphere. Therefore water moves from soil to plant and to the atmosphere. Diunduh dari sumber: ………. 30/10/2012

POTENSIAL AIR DALAM TANAMAN DAN TANAH
Potential = 0 Potential is + Potential = - Potential = +

TEGANGAN LENGAS TANAH SELAMA PERTUMBUHAN TANAMAN
Potential during the growing season in an aerobic soil (aerobic rice, Changping, China, 2002)

Tanah liat mampu menyimpan banyak air, tetapi dengan tegangan yang tinggi, sehingga akar tanaman sulit menyerapnya Tanah berpasir menyimpan sedikit air , tetapi dengan tegangan rendah , sehingga akar tanaman mudah menyerapnya A medium-textured, loamy soil, holds intermediate levels of water at intermediate tensions, so there is relatively much water for extraction by roots Tidak ada masalah pada tanah sawah tergenang, tetapi menjadi masalah serius kalau tanah mengering selama periode kering

Reduksi photosynthesis Percepatan kematian daun
Dampak KEKERINGAN When the soil is too dry (high soil water tension), it becomes too difficult for roots to take up water and water flow in the plant gets reduced: Reduksi transpirasi Reduksi photosynthesis Reduksi luas daun Daun menggulung Percepatan kematian daun Gabah hampa. USING WATER EFFECTIVELY IN A DRY CLIMATE OR DRY SEASON Water must be used economically in dry areas. To do this, the home garden manager should: prepare the soil so that the plant will grow in a basin-like or sunken space, to help prevent surface water runoff; select crops that grow well under drier conditions (e.g. cassava, sweet potato, eggplant, guava, mango, groundnut, safflower and nug); grow short-term vegetable crops near a water source such as a water well, a drain from a washing area, or a water tank. Diunduh dari sumber: ………. 28/10/2012

Reduksi transpirasi sbg fungsi tegangan lengas tanah (IR72)
leaf (Tact/Tpot) Soil water tension

Sterilitas Gabah Turner (1986): relationship between leaf rolling – increased canopy temperature Spikelet sterility Less grains Less yield

EFEK KEKERINGAN Soil moisture tension Less canopy transpiration
Reduced leaf expansion Less leaves Less canopy photosynthesis Less biomass Less grains Less yield Reduced partitioning to shoot Reduced leaf photosynthesis, transpiration Less light interception Leaf rolling Spikelet sterility Accelerated leaf death

Efek waktu terjadinya kekeringan: Paling peka saat pembungaan
O’Toole, 1984 Efek waktu terjadinya kekeringan: Paling peka saat pembungaan

Kekeringan di Serang, Banten.
Minggu, 5 Agustus :22 Beberapa petani membuat sumur bor di tengah sawah untuk menyelamatkan padi yang kekeringan di Kampung Astana, Ds Walikukun, Kec Carenang, Serang, Banten. Puluhan hektar sawah di lokasi itu terancam gagal panen akibat dilanda kekeringan sementara untuk membuat sumur bor tak semua petani mampu melakukannya karena harus mengeluarkan biaya tambahan. Diunduh dari: ….. 31/10/2012

Kekeringan Landa Pemalang, Lahan Sawah Jadi Retak-retak
Sabtu, 21 Juli :57 WIB Para petani tanaman padi di daerah Pantura (Pantai Utara), Jawa Tengah, kesulitan mendapatkan air irigasi di musim kemarau. Akibatnya, ribuan hektar tanaman padi di daerah Pemalang terancam gagal panen. Untuk menyelamatkan tanamannya, petani terpaksa harus membuat sumur bor yang disedot dengan mesin pompa air diesel. Kondisi ini menyebabkan biaya produksi meningkat. Bahkan, akibat kurangnya air irigasi ke sawah para petani, tanah sawah mengering dan retak-retak, membuat kondisi tanaman padi tidak maksimal. Jika tanah sawahnya tidak mendapatkan air, dikhawatirkan petani mengalami gagal panen. Diunduh dari: ….. 31/10/2012

Dampak kekeringan pada tanaman padi muda
Irigasi Kering, Puluhan Hektar Sawah Kekeringan (Post date: 05/07/ :19 REPORTER: ab. EDITOR: mdika Lebak - Sedikitnya 30 hektar lahan persawan di desa Talaga Hiang, Kecamatan Cipanas, Kabupaten Lebak, kekeringan. Dinas Pertanian Kabupaten Lebak masih terus melakukan upaya mengairi sawah warga tersebut dengan cara melakukan penyedotan air di Leuwi Herang untuk disalurkan ke saluran irigasi Leuwi Dolog. Kepala Bidang Sarana Dinas Pertanian Lebak, Rahmat Yuniar didampingi Kabid Produksi, Yuntani, mengatakan, saat ini lahan tanam petani di Desa Talaga Hiang yang luasnya mencapai 30 HA dilanda kekeringan akibat kemarau, bahkan sarana irigasi yang ada di daerah setempat yaitu Irigasi Leuwi Dolog tidak jalan sehingga tidak dapat membantu memenuhi kebutuhan air yang dibutuhkan para petani desa setempat DIUNDUH DARI: ….. 31/10/2012

. 5100 Hektare Sawah di Bekasi Terancam Kekeringan
Posted by korantrans pada Agustus 22, 2009 . Trans, Bekasi : Akibat bencana alam yang menimpa bangunan bagi sadap (BKG/4) di daerah irigasi (DI) Kedung Gede, Desa Cipayung, Bekasi, maka seluas 5100 dari hektare lahan sawah di daerah itu akan terncam kekeringan. Apabila tidak diatasi segera maka sejumlah petani di daerah tersebut, atau yang berada di saluran Rengas Bandung tidak bisa menggarap sawahnya karena tidak tersedianya air. Menurut Kusmana, untuk mengantisipasi agar tidak terjadinya kekeringan, maka pihaknya bekerjasama dengan Perusahaan Jasa Tirta Jatiluhur akan membuat saluran pengelak (kisdam) dengan cara pemasangan cerucuk bambu dan karung pasir. Hal ini dalakukan untuk menaikan debit ar pada saluran. Sementara untuk penanganan jangka panjangnya harus dilaksanakan pembangunan baru yang biaya fisiknya saja diperkirakan antara Rp 1 sampai Rp 2 miliar. Masalah bencana alam di BKG/4 ini sudah dilaporkan ke pusat melalui Balai Pengelola Wilayah Sungai (BPWS) Citarum di Bandung. Selain itu pihak PPK Irigasi 1 sekarang sedang melakukan koordinasi dengan pihak kecamatan dan Pemkab Bekasi, terutama dalam masalah jika ada pembebasan lahan apabila adanya pembangunan saluran baru. “ Akibaat bencana alam itu, BKG/4 ini memang perlu segera diatasi dengan pembangunan baru. Namun sebagai orang lapangan, saya usulkan pembangunannya lebih baik dilaksanakan dalam dua tahap. Hal ini mengingat waktu yang sudah mepet ke akhir tahun anggaran,” (Kusmana). Diunduh dari: 31/10/2012

PENANAMAN PADI SISTEM LEGOWO
Pola Tanam Pada areal beririgasi, lahan dapat ditanami padi 3 x setahun, tetapi pada sawah tadah hujan harus dilakukan pergiliran tanaman dengan palawija. Pergiliran tanaman ini juga dilakukan pada lahan beririgasi, biasanya setelah satu tahun menanam padi. Untuk meningkatkan produktivitas lahan, seringkali dilakukan tumpang sari dengan tanaman semusim lainnya, misalnya padi gogo dengan jagung atau padi gogo di antara ubi kayu dan kacang tanah. Pada pertanaman padi sawah, tanaman tumpang sari ditanam di pematang sawah, biasanya berupa kacang-kacangan.

SAWAH BER-TERAS-BANGKU
Analysis of percolation and seepage through paddy bunds Han-Chen Huang, Chen-Wuing Liu, Shih-Kai Chen, Jui-Sheng Chen. Journal of Hydrology. Volume 284, Issues 1–4, 22 December 2003, Pages 13–25. This study investigates percolation and seepage through the bunds of flat and terraced paddies. Field experiments were conducted in Hsin-Pu of Hsin-Chu County, Taiwan, to measure the soil water content of various types of bund. Measurements revealed that the soil was unsaturated along the sloped surface of the terrace. Experimental results also indicated that seepage face flow did not develop even after 2 days of heavy rainfall. A three-dimensional model, FEMWATER, was adopted to simulate percolation and lateral seepage under various bund conditions. In a flat paddy, the rate of percolation of bunds under which a plow sole was located, was 0.40 cm d−1, close to the average infiltration rate of a flooded paddy. The percolation of the bund without plow sole was 0.85 cm d−1, or double the average infiltration rate of a flooded paddy. Infiltration in the central area of a terraced paddy is mainly vertically downward, whereas flow near the bund is predominantly lateral. The paddy field near the bund has a high hydraulic gradient. The simulated infiltration flux into the bund (1.47 cm d−1) after 85 days of rice cultivation exceeded that into the central area (0.54 cm d−1) by a factor of The final percolation flux from the bund (1.24 cm d−1) also exceeded the final percolation from the plow sole (0.68 cm d−1) by a factor of The lateral seepage fluxes through the bund, downward and upward along the slope surface, are 2.01 and −2.12 cm d−1, respectively. However, the lateral seepage flux does not fully saturate the surface of the hillside soil. A simulation clearly shows that the seepage upstream of the paddy field does not move water downstream and is reused as subsurface return flow. Both experimental and simulation results clarify the mechanisms of water movement in the terraced paddy and reveal the existence of an unsaturated seepage face along the sloping surface of the terraced field. Diunduh dari sumber: /10/2012

Analysis of percolation and seepage through paddy bunds Han-Chen Huang, Chen-Wuing Liu, Shih-Kai Chen, Jui-Sheng Chen. Journal of Hydrology. Volume 284, Issues 1–4, 22 December 2003, Pages 13–25. Dua tipe rembesan air lateral melalui pematang sawah Diunduh dari sumber: /10/2012

Analysis of percolation and seepage through paddy bunds Han-Chen Huang, Chen-Wuing Liu, Shih-Kai Chen, Jui-Sheng Chen. Journal of Hydrology. Volume 284, Issues 1–4, 22 December 2003, Pages 13–25. Skema irisan melintang lahan sawah beterras dan terminologi yang lazim digunakan. Open arrows indicate soil water sampling locations and directions Diunduh dari sumber: /10/2012

Analysis of percolation and seepage through paddy bunds Han-Chen Huang, Chen-Wuing Liu, Shih-Kai Chen, Jui-Sheng Chen. Journal of Hydrology. Volume 284, Issues 1–4, 22 December 2003, Pages 13–25. Kecepatan aliran lapangan Darcy untuk rembesan lateral pada lahan sawah berteras (cm d−1). Diunduh dari sumber: /10/2012

Jaring-jaring Makanan dalam Ekosistem Sawah
Hubungan trofik pada ekosistem padi sawah yg menunjukkan pentingnya detritivores dan komponen vegetasi non-tanaman. Sumber: The three planks for ecological engineering (Heong et al. 2012) Diunduh dari sumber: …….. 28/10/2012

Nutrient Status of Paddy Soils
Ecological Sustainability of the Paddy Soil-Rice System in Asia Kazutake Kyuma Department of Environmental Science The University of Shiga Prefecture 2500 Hassaka-cho, Hikone City Japan 522, Nutrient Status of Paddy Soils General Redox Transformations under Waterlogged Conditions The most characteristic management practice in paddy rice cultivation is waterlogging, or submergence of the land surface. This brings about anaerobic conditions in the soil, due to the very slow diffusion rate of oxygen through water. Biologically, after the oxygen reserve in the soil is exhausted and aerobic microorganisms have all died, facultative anaerobes dominate for some time. As the anaerobioc conditions continue, these microorganisms are gradually replaced by obligate or strict anaerobes. The biological changes are accompanied by a very characteristic succession of chemical transformations of materials. Following the disappearance of molecular oxygen, nitrate is used as a substrate for denitrifiers. Manganic oxides are solubilized as a result of reduction to manganous ions, likewise orange yellow to reddish colored iron oxides are reduced to soluble ferrous ions, decolorizing the soil. Many fermentation reactions based on various organic substrates proceed along with these mineral transformations, producing carbon dioxide, ammoniacal nitrogen, low molecular weight organic acids, and so forth. As the soil becomes even more reductive, sulfate reducers, which are strict anaerobes, produce sulfides; and methanobacteria, also strict anaerobes, produce methane. Diunduh dari sumber: …….. 28/10/2012

Successive Chemical Transformations in Submerged Soils
Ecological Sustainability of the Paddy Soil-Rice System in Asia Kazutake Kyuma Department of Environmental Science The University of Shiga Prefecture 2500 Hassaka-cho, Hikone City Japan 522, All these biochemical changes occur vigorously for the first month after submergence, when readily decomposable organic matter, the energy source for microorganisms, is abundantly available. Past this stage, there will be a period when the supply of oxygen by diffusion, though extremely slow, exceeds its consumption at the soil/water interface. As all the oxygen is trapped by such reduced substances as ferrous and manganous ions at the interface, a thin oxidized, orange colored layer (normally a few millimeters thick) is differentiated from the underlying bulk of the strongly reduced, bluish-gray plow layer. Successive Chemical Transformations in Submerged Soils Diunduh dari sumber: …….. 28/10/2012

Supply of Basic Cations through Irrigation Water
Ecological Sustainability of the Paddy Soil-Rice System in Asia Kazutake Kyuma Department of Environmental Science The University of Shiga Prefecture 2500 Hassaka-cho, Hikone City Japan 522, Supply of Basic Cations through Irrigation Water At least 1000 to 1500 mm of water is used to irrigate paddy fields during one rice cropping season. Nutrients dissolved in water, particularly basic cations such as calcium, magnesium and potassium, as well as silica, are supplied to rice in the water. If we assume that 1000 mm of water is used for one crop of rice, 1 mg kg -1 or 1 ppm of a substance dissolved in water amounts to 10 kg/ha. According to the mean water quality of Japanese rivers, irrigation of 1000 mm of water brings to a paddy field 88 kg/ha of Ca, 19 kg/ha of Mg, 12 kg/ha of K, and 190 kg/ha of SiO 2. Usually more than 1000 mm of water is used for irrigation, so the amount of nutrients supplied to rice is larger. Water Quality of Japanese and Thai Rivers Diunduh dari sumber: …….. 28/10/2012

Supply of Nitrogen through Biological Nitrogen Fixation
Ecological Sustainability of the Paddy Soil-Rice System in Asia Kazutake Kyuma Department of Environmental Science The University of Shiga Prefecture 2500 Hassaka-cho, Hikone City Japan 522, Supply of Nitrogen through Biological Nitrogen Fixation There are paddy areas where rice has been cultivated for hundreds of years without receiving any fertilizer, but where yields are sustained at 1.5 to 2 mt/ha. It is estimated that about 20 kg of N is required to harvest 1 mt of paddy. Thus, it is difficult to explain how rice yields can be sustained for so long without any application of N. The greater part of N in paddy soils exists in soil organic matter. This tends to be conserved more in paddy soils than in upland soils, because of the anaerobic conditions. Microbial decomposition of the organic matter gradually releases ammoniacal N (NH 4 +-N). As NH 4 +-N is stable under anaerobic conditions, it is retained as a cation on negatively charged soil mineral and organic particles, until the time when rice roots take it up. Thus, the leaching of NH 4 +-N from paddy fields into the environment is not significant. Besides soil organic matter, there is another important source of N, i.e. biological N fixation. In paddy soils there are many microbes that are capable of fixing atmospheric N, such as blue-green algae, Clostridia, photosynthetic bacteria, and many of the heterotrophic bacteria in the rice rhizosphere. Estimates of the amount of biologically fixed N per crop of rice vary quite widely, but 30 to 40 kg/ha would be a reasonable figure. This amount of N is two or three times higher than the amount of N fixed in ordinary upland soils planted in non-leguminous crops. Interestingly enough, this amount of fixed N can explain the average yields of paddy obtained in unfertilized fields in southeast Asia (1.5 to 2 mt/ha) on the basis of 20 kg of N for 1 mt of paddy. Diunduh dari sumber: …….. 28/10/2012

Ecological Sustainability of the Paddy Soil-Rice System in Asia Kazutake Kyuma Department of Environmental Science The University of Shiga Prefecture 2500 Hassaka-cho, Hikone City Japan 522, Tanah sawah dilengkapi dnegan mekanisme siklus N yg bagus, dengan input melalui fiksasi N biologis dan outputnya melalui denitrification. Hal ini menjadi landasan bagu sustainabilitas budidaya padi sebagai sistem produksi pangan yg efisien. Diunduh dari sumber: …….. 28/10/2012

Negative Aspects of Soil Reduction
Ecological Sustainability of the Paddy Soil-Rice System in Asia Kazutake Kyuma Department of Environmental Science The University of Shiga Prefecture 2500 Hassaka-cho, Hikone City Japan 522, Negative Aspects of Soil Reduction Rice is known to suffer some physiological disorders under strongly reduced conditions. The best known is a root rot, caused by hydrogen sulfide evolved in soils that are poor in readily reducible iron oxides. These soils are often derived from pale colored, sandy, granitic sediments. They are poor, not only in iron oxides, but also in some other plant nutrients such as Mg, K and SiO 2. It is now known that root rot due to hydrogen sulfide is an acute case of the more general "akiochi" phenomenon observed in these "degraded paddy soils", as characterized above. In Japan, a nationwide project was carried out during the post-war period to ameliorate degraded paddy soils by dressing the soil with Fe-rich, more juvenile materials. With the aid of a government subsidy, the project was successfully completed, so that "akiochi" is no longer seen in Japan. There are large areas of paddy fields in southeast Asian countries that are characterized by the very low inherent potentiality of the soil. In fact, some of these deserve the name of "degraded" paddy soils. However, because of the generally low levels of both fertilizer inputs and rice yields, at present they may not be clearly differentiated from "normal" soils. Diunduh dari sumber: …….. 28/10/2012

Advantages of Paddy Rice Cultivation
Ecological Sustainability of the Paddy Soil-Rice System in Asia Kazutake Kyuma Department of Environmental Science The University of Shiga Prefecture 2500 Hassaka-cho, Hikone City Japan 522, Advantages of Paddy Rice Cultivation Comparison of Paddy Soils and Upland Soils The high level of resistance of paddy soils to erosive forces is even more important, from the viewpoint of sustainability. Upland soils tend to be eroded away unless they are properly protected. This is particularly true in the tropics, where the erosivity of rainfall is very high, and where upland soils usually have poor resistance to erosion. Paddy soils are most resistant to erosion when they are terraced and there are ridges around the field, as measures to retain surface water. In addition, paddy fields in the lowlands receive new sediments deposited from run-off that carries eroded topsoil down from the uplands, thus perpetuating soil fertility and productivity. Paddy soils have other advantages. In upland farming, crop rotation is a necessity to avoid a decline in yield due to diseases and pests that arise from a monoculture situation (soil sickness). In paddy fields, on the other hand, rice can be grown year after year without any clear sign of yield decline, over a considerable length of time. The alternation from aerobic to anaerobic conditions in a yearly cycle of rice farming is the best measure to remove the causes of soil sickness. No pathogens or soil-borne animals can survive such a drastic change in the redox environment. Diunduh dari sumber: …….. 28/10/2012

Intensification of Paddy Rice Cultivation and the Environment
Ecological Sustainability of the Paddy Soil-Rice System in Asia Kazutake Kyuma Department of Environmental Science The University of Shiga Prefecture 2500 Hassaka-cho, Hikone City Japan 522, Intensification of Paddy Rice Cultivation and the Environment Rice is the staple food for more than two billion people, most of whom live in developing countries where the population is still rapidly increasing. A study conducted by the International Rice Research Institute (IRRI 1989) reveals that to meet the projected growth in the demand for rice, the world's annual rough rice production must increase from 458 million mt in 1987 to 556 million mt by 2000 and to 758 million tons by This represents a 65% increase. For the leading rice-growing countries of south and southeast Asia, the same study indicates that the increase needed in rice production by 2020 is even higher, at about double the present level. The potential for expanding the area planted in rice seems to have become very restricted in south and southeast Asia. Most land resources have already been exploited to their fullest extent, and most of the readily manageable water resources also have been developed to irrigate paddy fields. Therefore, any further increase in the production of rice depends heavily on intensification in existing rice lands. Diunduh dari sumber: …….. 28/10/2012

Impact of Irrigation/Drainage and Chemical Inputs
Ecological Sustainability of the Paddy Soil-Rice System in Asia Kazutake Kyuma Department of Environmental Science The University of Shiga Prefecture 2500 Hassaka-cho, Hikone City Japan 522, Impact of Irrigation/Drainage and Chemical Inputs Intensifying rice cultivation could have various impacts on the environment. If good irrigation and drainage are provided, improved rice cultivars may be introduced, along with better management of fertilizer, weeds and pests. The construction of dams, and of irrigation and drainage canals, would normally bring more benefits than disadvantages to the regional environment, as long as they are properly planned and implemented. It improves water use efficiency, regulates floods and droughts, and, through these, improves the environmental quality. Increased use of chemical preparations, such as fertilizers, pesticides and herbicides, could be more hazardous. It is possible that they might pollute irrigation water and soil, and sometimes cause human health problems. This must, however, also be evaluated in comparison with the upland cultivation of other crops. Generally speaking, paddy rice cultivation could be less hazardous to the environment if it is intensified, with a high level of chemical inputs, than upland crop cultivation. Diunduh dari sumber: …….. 28/10/2012

Impact of Gas Emissions from Paddy Fields
Ecological Sustainability of the Paddy Soil-Rice System in Asia Kazutake Kyuma Department of Environmental Science The University of Shiga Prefecture 2500 Hassaka-cho, Hikone City Japan 522, Impact of Gas Emissions from Paddy Fields In relation to the global environment, air pollution from soil emissions is receiving more and more attention. The production of nitrous oxide (N 2O) from N fertilizers and manures is now considered to have an environmental impact. The gas is evolved in both nitrification and denitrification processes. The former is considered more important at present. It affects the destruction of ozone to oxygen, and also acts as a greenhouse gas. However, N 2O emissions from paddy fields are considered to be very low (De Datta and Buresh 1989). Paddy fields have been emitting methane since time immemorial. Therefore, the issue at the present time is the reason for the recent rapid increase in the atmospheric methane concentration of about 1% annually. Certainly, there was a large increase in the area planted in rice during the early postwar period, but if we take the most recent decade, 1980 to 1990, the world-wide annual rate of increase in rice area has been only 0.23% (IRRI 1993). Diunduh dari sumber: …….. 28/10/2012

.. Methane emission from a simulated rice field ecosystem as influenced by hydroquinone and dicyandiamide Xingkai Xu, Yuesi Wang, Xunhua Zheng, Mingxing Wang, Zijian Wang, Likai Zhou, Oswald Van Cleemput. Science of The Total Environment, Volume 263, Issues 1–3, 18 December 2000, Pages 243–253. A simple apparatus for collecting methane emission from a simulated rice field ecosystem was formed. With no wheat straw powder amended all treatments with inhibitor(s) had so much lower methane emission during rice growth than the treatment with urea alone (control), which was contrary to methane emission from the cut rice–soil system. Especially for treatments with dicyandiamide (DCD) and with DCD plus hydroquinone (HQ), the total amount of methane emission from the soil system and intact rice–soil system was 68.25–46.64% and 46.89–41.78% of the control, respectively. Hence, DCD, especially in combination with HQ, not only increased methane oxidation in the floodwater–soil interface following application of urea, but also significantly enhanced methane oxidation in rice root rhizosphere, particularly from its tillering to booting stage. Wheat straw powder incorporated into flooded surface layer soil significantly weakened the above-mentioned simulating effects. Regression analysis indicated that methane emission from the rice field ecosystem was related to the turnover of ammonium-N in flooded surface layer soil. Diminishing methane emissions from the rice field ecosystem was significantly beneficial to the growth of rice. Diunduh dari sumber: /10/2012

.. Methane emission from a simulated rice field ecosystem as influenced by hydroquinone and dicyandiamide Xingkai Xu, Yuesi Wang, Xunhua Zheng, Mingxing Wang, Zijian Wang, Likai Zhou, Oswald Van Cleemput. Science of The Total Environment, Volume 263, Issues 1–3, 18 December 2000, Pages 243–253. Hubungan antara emisi CH4 dari ekosistem padi sawah yang dilakukan aplikasi jerami gandum dan konsentrasi NH4+-N dalam air genangan (mg N l−1). Diunduh dari sumber: /10/2012

konsnetrasi NH4+-N dalam air genangan.
.. Methane emission from a simulated rice field ecosystem as influenced by hydroquinone and dicyandiamide Xingkai Xu, Yuesi Wang, Xunhua Zheng, Mingxing Wang, Zijian Wang, Likai Zhou, Oswald Van Cleemput. Science of The Total Environment, Volume 263, Issues 1–3, 18 December 2000, Pages 243–253. Hubungan antara emisi CH4 dari ekosistem padi sawah tanpa aplikasi jerami gandum dan konsnetrasi NH4+-N dalam air genangan. Diunduh dari sumber: /10/2012

SAWAH = WETLANDS Atmospheric methane (CH4) is an important greenhouse gas. On a scale of 100 years, it is approximately 20 times more effective than carbon dioxide (CO2). The total annual CH4 emission both from natural and anthropogenic terrestrial sources to the atmosphere is about 580 Tg (CH4) yr-1. The contribution of natural and man-made wetlands (e.g. rice paddy) to this global total varies between 20 and 40%. Thereby, natural wetlands are the major non-anthropogenic source of methane at present and rice agriculture accounts for some 17% of the anthropogenic CH4 emissions. This is because of the prevailing anaerobic conditions in these ecosystems, their high organic matter contents and their global distribution. Northern wetlands (>30° N) for example constitute about 60% of the global wetland area and emit a quarter to a third of the total CH4 originating from wet soils. Microbial turnover of methane and transport pathways of gases in wetlands. Diunduh dari sumber: …….. 28/10/2012

Yu Xiao, Gaodi Xie, Chunxia Lu, Xianzhong Ding, Yao Lu.
The value of gas exchange as a service by rice paddies in suburban Shanghai, PR China Yu Xiao, Gaodi Xie, Chunxia Lu, Xianzhong Ding, Yao Lu. Agriculture, Ecosystems & Environment. Volume 109, Issues 3–4, 1 September 2005, Pages 273–283 Valuating ecosystem services is crucial for making the importance of ecosystem functioning explicit to the public and decision makers as well as scientists. Investigations of the value of agricultural ecosystems have focused mainly on value food and fibre production and been carried out at relatively coarse scales. However, such studies may have underestimated services provided by agricultural ecosystems because they did not consider additional services such as gas regulation, pollination control, nutrient transformation, and landscape aesthetics. We present the results of a field experimental study of gas regulation services and their economic values provided by rice paddy ecosystems in suburban Shanghai, China. Two major components of gas regulation by paddy fields are O2 emissions and greenhouse gases (GHGs) regulation (including the uptake of CO2 and emissions of CH4 and N2O). Seasonal emissions of O2 from experimental plots with different urea application rates ranged from 25,365 to 32,612 kg ha−1 year−1, with an economic value of 9549–12,277 RMB ha−1 year−1 (Chinese currency; 1 euro = RMB, Jan 18, 2005). The net GHGs regulation ranged from 705 to 2656 kg CO2C ha−1 year−1, with an economic value ranging from 531 to 2000 RMB ha−1 year−1. Thus, the overall economic value of gas regulation provided by the rice paddy ecosystems ranged from 10,080 to 14,277 RMB ha−1 year−1. Our results refined, and in some cases, modified previous estimates of agricultural ecosystem services based mainly on coarse-scale studies. Our study also demonstrated a systematic method to valuate the gas regulation services provided by rice paddy ecosystems, which will be useful for understanding regulation of atmospheric chemistry and greenhouse effects by other agriculture ecosystems.. Diunduh dari sumber: /10/2012

The value of gas exchange as a service by rice paddies in suburban Shanghai, PR China Yu Xiao, Gaodi Xie, Chunxia Lu, Xianzhong Ding, Yao Lu. Agriculture, Ecosystems & Environment. Volume 109, Issues 3–4, 1 September 2005, Pages 273–283 . Ilustrasi bilik statis yg dipakai untuk mengukur aliran emisi gas di lahan padi sawah. Diunduh dari sumber: /10/2012

The value of gas exchange as a service by rice paddies in suburban Shanghai, PR China Yu Xiao, Gaodi Xie, Chunxia Lu, Xianzhong Ding, Yao Lu. Agriculture, Ecosystems & Environment. Volume 109, Issues 3–4, 1 September 2005, Pages 273–283 Estimasi nilai-nilai ekonomi serapan CO2, emisi CH4, emisi N2O, dan keseluruhan regulasi gas rumah kaca dari ekosistem padi sawah selama musim tumbuhnya dnegan berbagai dosis aplikasi urea di daerah sub-urban Shanghai, China. Diunduh dari sumber: /10/2012

DINAMIKA NITROGEN EKOSISTEM SAWAH
A coupled soil water and nitrogen balance model for flooded rice fields in India V.M. Chowdary, N.H. Rao, P.B.S. Sarma. Agriculture, Ecosystems & Environment. Volume 103, Issue 3, August 2004, Pages 425–441. In the present study a simple model for assessing concentration of nitrate in water percolating out of the flooded rice (Oryza Sativa) fields is presented. The model considers all the important nitrogen (N) transformation processes that take place in flooded rice fields such as urea hydrolysis, volatilization, nitrification, mineralization, immobilization, denitrification, crop uptake and leaching. It is based on coupling of soil water and N-balance models. The coupled model also accounts for weather, and timings and amounts of water and fertilizer applications. All the N-transformations except plant uptake and leaching are considered to follow first-order kinetics. The simulation results show that urea hydrolysis is completed within 7 days of fertilizer application. It was also observed that the volatilization loss of N varies from 25 to 33% of the applied fertilizer and 75% of the total volatilization loss occurs within 7 days of urea application. The modeled leaching losses from the field experiments varied from 20 to 30% of the applied N. The N-uptake by the crop increased immediately after the application of fertilizer and decreased at 60 days after transplanting. The model is sufficiently general to be used in a wide range of conditions for quantification of nutrient losses by leaching and developing water and fertilizer management strategies for rice in irrigated areas. Diunduh dari sumber: …….. 29/10/2012

A coupled soil water and nitrogen balance model for flooded rice fields in India V.M. Chowdary, N.H. Rao, P.B.S. Sarma. Agriculture, Ecosystems & Environment. Volume 103, Issue 3, August 2004, Pages 425–441. Skematik transformasi N pada lahan padi sawah yg tergenang Diunduh dari sumber: …….. 29/10/2012

A coupled soil water and nitrogen balance model for flooded rice fields in India V.M. Chowdary, N.H. Rao, P.B.S. Sarma. Agriculture, Ecosystems & Environment. Volume 103, Issue 3, August 2004, Pages 425–441. Zonasi ideal lahan sawah untuk penelitian neraca N. Diunduh dari sumber: …….. 29/10/2012

A coupled soil water and nitrogen balance model for flooded rice fields in India V.M. Chowdary, N.H. Rao, P.B.S. Sarma. Agriculture, Ecosystems & Environment. Volume 103, Issue 3, August 2004, Pages 425–441. Schematic representation of nitrogen balance model. Diunduh dari sumber: …….. 29/10/2012

A coupled soil water and nitrogen balance model for flooded rice fields in India V.M. Chowdary, N.H. Rao, P.B.S. Sarma. Agriculture, Ecosystems & Environment. Volume 103, Issue 3, August 2004, Pages 425–441. Serapan Nitrogen tanaman padi di Pantnagar, Uttar Pradesh, India. aplikasi pupuk Basal (80 kg N ha−1) dan (b) aplikasi bertahap ( kg N ha−1). Diunduh dari sumber: …….. 29/10/2012

B.A.M. Bouman, E. Humphreys, T.P. Tuong, R. Barker.
AIR DAN PADI SAWAH Rice and Water B.A.M. Bouman, E. Humphreys, T.P. Tuong, R. Barker. Advances in Agronomy. Volume 92, 2007, Pages 187–237. . Rice environments also provide unique—but as yet poorly understood—ecosystem services such as the regulation of water and the preservation of aquatic and terrestrial biodiversity. Rice production under flooded conditions is highly sustainable. In comparison with other field crops, flooded rice fields produce more of the greenhouse gas methane but less nitrous oxide, have no to very little nitrate pollution of the groundwater, and use relatively little to no herbicides. Flooded rice can locally raise groundwater tables with subsequent risk of salinization if the groundwater carries salts, but is also an effective restoration crop to leach accumulated salts from the soil in combination with drainage. Water scarcity is expected to shift rice production to more water‐abundant delta areas, and to lead to crop diversification and more aerobic (nonflooded) soil conditions in rice fields in water‐short areas. In these latter areas, investments should target the adoption of water‐saving technologies, the reuse of drainage and percolation water, and the improvement of irrigation supply systems. A suite of water‐saving technologies can help farmers reduce percolation, drainage, and evaporation losses from their fields by 15–20% without a yield decline. However, greater understanding of the adverse effects of increasingly aerobic field conditions on the sustainability of rice production, environment, and ecosystem services is needed. In drought‐, salinity‐, and flood‐prone environments, the combination of improved varieties with specific management packages has the potential to increase on‐farm yields by 50–100% in the coming 10 years, provided that investment in research and extension is intensified. Diunduh dari sumber: …….. 29/10/2012

AIR DAN PADI SAWAH Rice and Water B.A.M. Bouman, E. Humphreys, T.P. Tuong, R. Barker. Advances in Agronomy. Volume 92, 2007, Pages 187–237. Neraca air di lahan padi sawah dataran rendah. C, rumbai kapiler; E, evaporasi; I, irrigasi; O, limpasan atas pematang; P, perkolasi; R, curah hujan; S, rembesan-samping (seepage); T, transpirasi. Diunduh dari sumber: …….. 29/10/2012

AIR DAN PADI SAWAH Rice and Water B.A.M. Bouman, E. Humphreys, T.P. Tuong, R. Barker. Advances in Agronomy. Volume 92, 2007, Pages 187–237. Aliran air permukaan dna bawah permukaan pada lahan sawah. D, drainage (overbund flow); I, irigasi; P, perkolasi; S, rembesan-seepage. Diunduh dari sumber: …….. 29/10/2012

D.F. Tabbal, B.A.M. Bouman, S.I. Bhuiyan, E.B. Sibayan, M.A. Sattar.
HEMAT AIR PADI SAWAH . On-farm strategies for reducing water input in irrigated rice; case studies in the Philippines D.F. Tabbal, B.A.M. Bouman, S.I. Bhuiyan, E.B. Sibayan, M.A. Sattar. Agricultural Water Management. Volume 56, Issue 2, 30 July 2002, Pages 93–112. This paper reports results of on-farm experiments in the Philippines to reduce water input by water-saving irrigation techniques and alternative crop establishment methods, such as wet and dry seeding. With continuous standing water, direct wet-seeded rice yielded higher than traditional transplanted rice by 3–17%, required 19% less water during the crop growth period and increased water productivity by 25–48%. Direct dry-seeded rice yielded the same as transplanted and wet-seeded rice, but can make more effective use of early season rainfall in the wet season and save irrigation water for the subsequent dry season. Direct seeding can further reduce water input by shortening the land preparation period. In transplanted and wet-seeded rice, keeping the soil continuously around saturation reduced yields on average by 5% and water inputs by 35% and increased water productivity by 45% compared with flooded conditions. Intermittent irrigation further reduced water inputs but at the expense of increased yield loss. Under water-saving irrigation, wet-seeded rice out-yielded transplanted rice by 6–36% and was a suitable establishment method to save water and retain high yields. Groundwater depth greatly affected water use and the possibilities of saving water. With shallow groundwater tables of 10–20 cm depth, irrigation water requirements and potential water savings were low but yield reductions were relatively small. The introduction of water-saving technologies at the field level can have implications for the hydrology and water use at larger spatial scale levels. Diunduh dari sumber: …….. 29/10/2012

D.F. Tabbal, B.A.M. Bouman, S.I. Bhuiyan, E.B. Sibayan, M.A. Sattar.
HEMAT AIR PADI SAWAH . On-farm strategies for reducing water input in irrigated rice; case studies in the Philippines D.F. Tabbal, B.A.M. Bouman, S.I. Bhuiyan, E.B. Sibayan, M.A. Sattar. Agricultural Water Management. Volume 56, Issue 2, 30 July 2002, Pages 93–112. Komponen-komponen neraca air di lahan sawah yg tergenang dan dilumpurkan. Diunduh dari sumber: …….. 29/10/2012

NERACA AIR SAWAH TADAH-HUJAN
Water balance simulation model for optimal sizing of on-farm reservoir in rainfed farming system Dipankar Roy, Sudhindra N. Panda, B. Panigrahi. Computers and Electronics in Agriculture. Volume 65, Issue 1, January 2009, Pages 114–124. . The on-farm reservoir (OFR) is used to harvest the surplus water from the diked crop field and recycle the stored water as supplemental irrigation to rice in monsoon (rainy) and non-rice (dry) crops in winter season under rainfed farming system. A user-friendly software, using Visual Basic 6.0 program, is developed to find out the optimal size of the OFR in terms of percentage of field area (here in called as OFR sizes throughout the manuscript) by simulating the water balance model parameters of the crop field and the OFR. The software is meant for all the concerned including the engineers, planners and farming community for any monsoon influenced cropping area, which uses rainfed agriculture. The menu driven system is flexible enough to simulate the OFR sizes for various combinations of the OFR geometry, field sizes, and the cropping systems. The user has to specify the crops to be grown in the fields, irrigation management practices of the crops, types of OFR (lined or unlined), side slope, depth of OFR, and field sizes. Evapotranspiration sub-model is embedded with the main model to compute the ET from the meteorological data. As model application, the developed model is used to simulate the OFR sizes for the rice–mustard and rice–groundnut cropping systems using the experimental observed and meteorological data of the study area located at Indian Institute of Technology, Kharagpur in eastern India. The water balance model parameters of the crop field are validated with 2 years of observed data from the experimental field of above mentioned study area. The study reveals that rice–groundnut cropping system requires higher OFR sizes than rice–mustard cropping systems. Moreover, it is observed that as the field areas increase, the OFR sizes for each cropping systems is found to decrease. Diunduh dari sumber: 29/10/2012

NERACA AIR SAWAH TADAH-HUJAN
Water balance simulation model for optimal sizing of on-farm reservoir in rainfed farming system Dipankar Roy, Sudhindra N. Panda, B. Panigrahi. Computers and Electronics in Agriculture. Volume 65, Issue 1, January 2009, Pages 114–124. Skematik parameter neraca air lahan padi sawah dan OFR dengan volume kontrolnya. Diunduh dari sumber: 29/10/2012

KEHILANGAN AIR DARI SAWAH
. Causes of high water losses from irrigated rice fields: field measurements and results from analogue and digital models S.H. Walker. Agricultural Water Management. Volume 40, Issue 1, 1 March 1999, Pages 123–127. Pada lahan sawah dengan pematang yang permanen, banyak air yg hilang memalui rembesan-seepage lateral dari bidang olah memasuki pematang dan dari pematang air bergerak vertikal ke bawah menuju groundwater. Lateral percolation losses increase with increases in field water depth, bund width, aquifer thickness and depth to groundwater. These losses do not occur in systems where the bunds are reformed every year. Diunduh dari sumber: 29/10/2012

. Causes of high water losses from irrigated rice fields: field measurements and results from analogue and digital models S.H. Walker. Agricultural Water Management. Volume 40, Issue 1, 1 March 1999, Pages 123–127. Hypothesis: Perkolasi lateral ke arah bawah melalui pematang lebih besar dibandingkan dnegan perkolasi vertikal melalui lapisan tapak kedap air di bidang olah lahan sawah. Diunduh dari sumber: 29/10/2012

. Causes of high water losses from irrigated rice fields: field measurements and results from analogue and digital models S.H. Walker. Agricultural Water Management. Volume 40, Issue 1, 1 March 1999, Pages 123–127. Observasi lapangan membuktikan adanya inflow ke pematang dari lahan yang di sekitarnya. Diunduh dari sumber: 29/10/2012

CO2 & PANAS PADA EKOSISTEM SAWAH
. CO2/heat fluxes in rice fields: Comparative assessment of flooded and non-flooded fields in the Philippines Ma. Carmelita R. Alberto, Reiner Wassmann, Takashi Hirano, Akira Miyata, Arvind Kumar, Agnes Padre, Modesto Amante. Agricultural and Forest Meteorology. Volume 149, Issue 10, 1 October 2009, Pages 1737–1750. The aerobic rice fields had higher sensible heat flux (H) and lower latent heat flux (LE) compared to flooded fields. On seasonal average, aerobic rice fields had 48% more sensible heat flux while flooded rice fields had 20% more latent heat flux. Consequently, the aerobic rice fields had significantly higher Bowen ratio (0.25) than flooded fields (0.14), indicating that a larger proportion of the available net radiation was used for sensible heat transfer or for warming the surrounding air. The total C budget integrated over the cropping period showed that the net ecosystem exchange (NEE) in flooded rice fields was about three times higher than in aerobic fields while gross primary production (GPP) and ecosystem respiration (Re) were 1.5 and 1.2 times higher, respectively. The high GPP of flooded rice ecosystem was evident because the photosynthetic capacity of lowland rice is naturally large. The Re of flooded rice fields was also relatively high because it was enhanced by the high photosynthetic activities of lowland rice as manifested by larger above-ground plant biomass. The NEE, GPP, and Re values for flooded rice fields were −258, 778, and 521 g C m−2, respectively. For aerobic rice fields, values were −85, 515, and 430 g C m−2 for NEE, GPP, and Re, respectively. The ratio of Re/GPP in flooded fields was 0.67 while it was 0.83 for aerobic rice fields. Diunduh dari sumber: 29/10/2012

. CO2/heat fluxes in rice fields: Comparative assessment of flooded and non-flooded fields in the Philippines Ma. Carmelita R. Alberto, Reiner Wassmann, Takashi Hirano, Akira Miyata, Arvind Kumar, Agnes Padre, Modesto Amante. Agricultural and Forest Meteorology. Volume 149, Issue 10, 1 October 2009, Pages 1737–1750. Radiasi matahari (SR), curah hujan, dan suhu ambient selama musim kering 2008 , 11 January hingga 15 May. Diunduh dari sumber: 29/10/2012

. CO2/heat fluxes in rice fields: Comparative assessment of flooded and non-flooded fields in the Philippines Ma. Carmelita R. Alberto, Reiner Wassmann, Takashi Hirano, Akira Miyata, Arvind Kumar, Agnes Padre, Modesto Amante. Agricultural and Forest Meteorology. Volume 149, Issue 10, 1 October 2009, Pages 1737–1750. Hubungan antara jumlah respirasi ekosistem harian (Re) dan potensial air tanah (SWP) pada kedalmaan tanah 15 cm lahan sawah aerobik selama musim kering 2008. Daily Re was grouped into 24 bins and averaged with equal number of data points per bin. Triangles denote values during vegetative to panicle initiation stage; squares denote values during reproductive to ripening stage; circles denote values during harvest stage. Diunduh dari sumber: 29/10/2012

. CO2/heat fluxes in rice fields: Comparative assessment of flooded and non-flooded fields in the Philippines Ma. Carmelita R. Alberto, Reiner Wassmann, Takashi Hirano, Akira Miyata, Arvind Kumar, Agnes Padre, Modesto Amante. Agricultural and Forest Meteorology. Volume 149, Issue 10, 1 October 2009, Pages 1737–1750. Hubungan antara produksi primer bruto harian (GPP) dan potensial air tanah (SWP) pada kedalaman tanah 15 cm sawah aerobik semala musim kering 2008. Daily GPP was grouped into 24 bins and averaged with equal number of data points per bin. Vertical bars denote standard error. Triangles denote values during vegetative to panicle initiation stage; squares denote values during reproductive to ripening stage; circles denote values during harvest stage. Diunduh dari sumber: 29/10/2012

. CO2/heat fluxes in rice fields: Comparative assessment of flooded and non-flooded fields in the Philippines Ma. Carmelita R. Alberto, Reiner Wassmann, Takashi Hirano, Akira Miyata, Arvind Kumar, Agnes Padre, Modesto Amante. Agricultural and Forest Meteorology. Volume 149, Issue 10, 1 October 2009, Pages 1737–1750. Hubungan antara pertukaran neto CO2 ekosistem (NEE) pada radiasi aktif fotosintetik (PAR) lebih dari 1000 μmol m−2 s−1 dan defisit tekanan uap (VPD) di lahan sawah aerobik (a) ketika potensial air tanah (SWP) pada kedalaman tanah 15 sebesar <−100 kPa dan (b) lahan sawah tergenang, selama musim kering 2008. Half-hourly data were sorted by VPD and bin averaged with equal number of data per bin. Vertical bars denote standard error. Diunduh dari sumber: 29/10/2012

. CO2/heat fluxes in rice fields: Comparative assessment of flooded and non-flooded fields in the Philippines Ma. Carmelita R. Alberto, Reiner Wassmann, Takashi Hirano, Akira Miyata, Arvind Kumar, Agnes Padre, Modesto Amante. Agricultural and Forest Meteorology. Volume 149, Issue 10, 1 October 2009, Pages 1737–1750. Variasi musim untuk parameter harian (a) NEE, Re, dan GPP ; dan (b) potensial air tanah (SWP) pada kedalaman tanah 5 cm dan 15 cm lahan sawah aerobik selama musim kering 2008 mulai 21 January hingga 12 May. The vertical bars show the different growth stages of the aerobic rice (vegetative, tillering to panicle initiation, reproductive, heading to flowering, ripening, and harvest). Diunduh dari sumber: 29/10/2012

JASA-JASA EKOSISTEM SAWAH
. Ecosystem services by paddy fields as substitutes of natural wetlands in Japan Yosihiro Natuhara Ecological Engineering. Available online 22 May 2012. Ecosystem services provided by paddy fields include; groundwater recharge, production of non-rice foods, flood control, soil erosion and landslide prevention, climate-change mitigation, water purification, culture and landscape, and support of ecosystems and biodiversity. Among these services, the value of services that regulate ecosystem functions was estimated to be US$ 72.8 billion in Japan. More than 5000 species have been recorded in paddy fields and the surrounding environment. Because paddy fields are artificially disturbed by water level management, plowing, and harvest, most species move between paddy fields and the surrounding environment. The linkage between paddy fields and the associated environment plays an important role in biodiversity. Two changes that have affected the ecosystem of paddy fields are modernization and abandonment of farming. Satoyama, a traditional socio-ecological production landscape, which provided a functional linkage between paddy fields and the associated environment has lost its functions. Biodiversity-conscious rice farming has been promoted by collaborations among farmers, consumers and governments. Biodiversity certification programs are successful examples of biodiversity-conscious framing. In these programs incentives include direct payments and/or premium prices paid by consumers, as well as farmers willingness to improve the safety of food and environment. Diunduh dari sumber: …….. 29/10/2012

. Ecosystem services by paddy fields as substitutes of natural wetlands in Japan Yosihiro Natuhara Ecological Engineering. Available online 22 May 2012. Lanskap sawah dan pergerakan spesies. Diunduh dari sumber: …….. 29/10/2012

. Ecosystem services by paddy fields as substitutes of natural wetlands in Japan Yosihiro Natuhara Ecological Engineering. Available online 22 May 2012. Pengelolaan air di lahan sawah dan siklus hidup spesies. Periode waktu genangan dan drainage mempengaruhi daya hidup spesies akuatik O. albistylum. Diunduh dari sumber: …….. 29/10/2012

. Ecosystem services by paddy fields as substitutes of natural wetlands in Japan Yosihiro Natuhara Ecological Engineering. Available online 22 May 2012. Konsolidasi lahan dna perbaikan drainage. Conversion to fields equipped with deeper ditches for rapid draining has almost eliminated wet winter paddy fields. The gap between paddy and drainage ditch prevents fish from migrating to the paddy. Diunduh dari sumber: …….. 29/10/2012

. Ecosystem services by paddy fields as substitutes of natural wetlands in Japan Yosihiro Natuhara Ecological Engineering. Available online 22 May 2012. Dampak perubahan lahan sawah pada ikan (sumber: Katano, 2000). Diunduh dari sumber: …….. 29/10/2012

NERACA KARBON EKOSISTEM SAWAH
. Rice paddy fields are also one of the typical agricultural ecosystems in Monsoon Asia. Among them, single rice cropping paddies that dominates in northeastern Asia are characterized by two contrasting periods, a flooded growing period and dry fallowed period which lasts two thirds of a year. From the analyses using stable isotopes of water and carbon, the largest carbon input was CO2 fixation by photosynthesis of rice, where 64-65% of the fixed carbon was harvested in autumn. Inflow and outflow of dissolved carbon accounted for 5-9% of the total input and output Diunduh dari sumber: …….. 29/10/2012

Soil and Tillage Research. Volume 126, January 2013, Pages 60–71.
Management-induced organic carbon accumulation in paddy soils: The role of organo-mineral associations Livia Wissing, Angelika Kölbl, Werner Häusler , Peter Schad, Zhi-Hong Cao, Ingrid Kögel-Knabner. Soil and Tillage Research. Volume 126, January 2013, Pages 60–71. Iron (Fe) oxides strongly interact with organic matter in soil and play an important role in the stabilization of organic matter. These processes are often influenced by soil cultivation, including tillage, crop rotation and irrigation. We assessed the effect of Fe oxides on organic carbon (OC) accumulation during the development of soils used for paddy rice production in comparison to non-irrigated cropping systems. Soil samples were taken from two chronosequences derived from uniform parent material in the Zhejiang Province (PR China). Bulk soils and soil fractions were analyzed for OC concentrations, soil mineralogy and soil organic matter (SOM) composition was determined by solid-state 13C NMR spectroscopy. Paddy soils were characterized by increasing OC concentrations, from 18 mg g−1 to 30 mg g−1, during 2000 years of rice cultivation, but OC concentrations of non-paddy soils were low in all age classes (11 mg g−1). SOM composition revealed from Solid-state 13C NMR spectroscopy did not change during pedogenesis in either chronosequence. Selective enrichment of lignin-derived compounds, caused by long-term paddy rice management, could not be confirmed by the present study. The management of paddy soils creates an environment of Fe oxide formation which was different to those in non-paddy soils. Paddy soils are dominated by poorly crystalline Fe oxides (Feo) and significantly lower content of crystalline Fe oxides (Fed − Feo). This was in contrast to non-paddy soils, which are characterized by high proportions of crystalline Fe oxides. The paddy-specific Fe oxide composition was effective after only 50 years of soil development and the proportion Fe oxides did not alter during further pedogenesis. This chronosequence study revealed that the potential for OC accumulation was higher in paddy versus non-paddy soils and was already reached at earliest stages of paddy soil development. Changes in paddy soil management associated with redox cycle changes will not only affect Fe oxide composition of paddy soils but most probably also OC storage potential. Diunduh dari sumber: …….. 31/10/2012

Soil and Tillage Research. Volume 126, January 2013, Pages 60–71.
Management-induced organic carbon accumulation in paddy soils: The role of organo-mineral associations Livia Wissing, Angelika Kölbl, Werner Häusler , Peter Schad, Zhi-Hong Cao, Ingrid Kögel-Knabner. Soil and Tillage Research. Volume 126, January 2013, Pages 60–71. Hubungan antara besi ekstraks oksalat (Feo) dan bahan organik (OC) pada tanah-tanah padi sawah (P) dan non-paddy (NP) fraksi tanah (20–6.3 μm = debu medium; 6.3–2 μm = debu halus; 2–0.2 μm = liat kasar; <0.2 μm = liat halus). Diunduh dari sumber: …….. 31/10/2012

PLoS One. 2012; 7(5): e34642. Published online 2012 May 4.
Effects of Tillage and Nitrogen Fertilizers on CH4 and CO2 Emissions and Soil Organic Carbon in Paddy Fields of Central China Li Cheng-Fang, Zhou Dan-Na, Kou Zhi-Kui, Zhang Zhi-Sheng, Wang Jin-Ping, Cai Ming-Li, and Cao Cou-Gui. Quantifying carbon (C) sequestration in paddy soils is necessary to help better understand the effect of agricultural practices on the C cycle. The objective of the present study was to assess the effects of tillage practices [conventional tillage (CT) and no-tillage (NT)] and the application of nitrogen (N) fertilizer (0 and 210 kg N ha−1) on fluxes of CH4 and CO2, and soil organic C (SOC) sequestration during the 2009 and 2010 rice growing seasons in central China. Application of N fertilizer significantly increased CH4 emissions by 13%–66% and SOC by 21%–94% irrespective of soil sampling depths, but had no effect on CO2 emissions in either year. Tillage significantly affected CH4 and CO2 emissions, where NT significantly decreased CH4 emissions by 10%–36% but increased CO2 emissions by 22%–40% in both years. The effects of tillage on the SOC varied with the depth of soil sampling. NT significantly increased the SOC by 7%–48% in the 0–5 cm layer compared with CT. However, there was no significant difference in the SOC between NT and CT across the entire 0–20 cm layer. Hence, our results suggest that the potential of SOC sequestration in NT paddy fields may be overestimated in central China if only surface soil samples are considered. Diunduh dari sumber: 31/10/2012

Effects of Tillage and Nitrogen Fertilizers on CH4 and CO2 Emissions and Soil Organic Carbon in Paddy Fields of Central China Li Cheng-Fang, Zhou Dan-Na, Kou Zhi-Kui, Zhang Zhi-Sheng, Wang Jin-Ping, Cai Ming-Li, and Cao Cou-Gui. Keseluruhan proses emisi CH4 dari sawah, termasuk produksi, oksidasi, dan transpornya ke artmosfir dipengaruhi oleh praktek pertanian , seperti pengolahan tanah dan pemupukan nitrogen [1]–[3]. Tillage affects a range of biological, chemical, and physical properties, thereby affecting the release of CH4 [4]. No-tillage (NT) has been reported to reduce CH4 emissions from paddy soils because rice straw is placed on the soil surface under NT and the soil conditions are more oxidative than those of conventional tillage (CT) [3], [5]. Emisi CH4 dari sawah dilaporkan sangat dipemngaruhi oleh bentuk dan dosis pupuk N [6]. Chu H, Hosen Y, Yagi K. NO, N2O, CH4 and CO2 fluxes in winter barley field of Japanese Andisol as affected by N fertilizer management. Soil Biol Biochem. 2007;39:330–339. Guo J, Zhou C. Greenhouse gas emissions and mitigation measures in Chinese agroecosystems. Agric Forest Meteorol. 2007;142:270–277. Harada H, Kobayashi H, Shindo H. Reduction in greenhouse gas emissions by no-tilling rice cultivation in Hachirogata polder, northern Japan: life-cycle inventory analysis. Soil Sci Plant Nutr. 2007;53:668–677. Oorts K, Merckx R, Gréhan E, Labreuche J, Nicolardot B. Determinants of annual fluxes of CO2 and N2O in long–term no–tillage and conventional tillage systems in northern France. Soil Till Res. 2007;95:133–148. Liang W, Shi Y, Zhang H, Yue J, Huang GH. Greenhouse gas emissions from northeast China rice fields in fallow season. Pedosphere. 2007;17(5):630–638. Minami K. The effect of nitrogen fertilizer use and other practices on methane emission from flooded rice. Fertil Res. 1995;40:71–84. Diunduh dari sumber: 31/10/2012

Effects of Tillage and Nitrogen Fertilizers on CH4 and CO2 Emissions and Soil Organic Carbon in Paddy Fields of Central China Li Cheng-Fang, Zhou Dan-Na, Kou Zhi-Kui, Zhang Zhi-Sheng, Wang Jin-Ping, Cai Ming-Li, and Cao Cou-Gui. Perubahan emisi CH4 dari lahan sawah dengan beragam pengelolaannya selama periode musim tanam padi 2009 dan 2010. The pattern of seasonal CH4 emission fluxes was similar across NT and CT treatments during the 2009 and 2010 rice growing seasons . In both years, the CH4 emission fluxes in the four treatment groups were all initially low, increased gradually, and then peaked in mid-July (about 4–5 weeks after sowing). Thereafter, the CH4 emission fluxes declined gradually and remained relatively low until harvesting when the CH4 emission fluxes were lowest. Diunduh dari sumber: 31/10/2012

Effects of Tillage and Nitrogen Fertilizers on CH4 and CO2 Emissions and Soil Organic Carbon in Paddy Fields of Central China Li Cheng-Fang, Zhou Dan-Na, Kou Zhi-Kui, Zhang Zhi-Sheng, Wang Jin-Ping, Cai Ming-Li, and Cao Cou-Gui. EMISI CO2 Application of N fertilizer increases plant biomass production, stimulating soil biological activity, and consequently, CO2 emission [40]. Wilson and Al-Kaisi [41], as well as Iqbal et al. [13], observed increased CO2 emissions caused by N fertilizer application. By contrast, Burton et al. [15] and DeForest et al. [16] indicated that reduced extracellular enzyme activities and fungal populations resulting from N fertilizer application resulted in decreased soil CO2 emissions. We observed no significant effect of N fertilizer application on cumulative CO2 emissions , consistent with the results reported by Almaraz et al. [42]. This finding may be due to the fact that CO2 is reduced to CH4 under anaerobic conditions, thus leading to significant differences in CH4 emissions rather than in CO2 emissions between fertilized and unfertilized treatment areas. [13]. Iqbal J, Hu RG, Lin S, Hatano R, Feng ML, et al. CO2 emission in a subtropical red paddy soil (Ultisol) as affected by straw and N fertilizer applications: a case study in Southern China. Agric Ecosyst Environ. 2009;131:292–302. [14]. Xiao Y, Xie G, Lu G, Ding X, Lu Y. The value of gas exchange as a service by rice paddies in suburban Shanghai, PR China. Agric Ecosyst Environ. 2005;109:273–283. [15]. Burton AJ, Pregitzer KS, Crawford JN, Zogg GP, Zak DR. Simulated chronic NO3-deposition reduces soil respiration in Northern hardwood forests. Global Change Biol. 2004;10:1080–1091. [16]. DeForest JL, Zak DR, Pregitzer KS, Burton AJ. Atmospheric nitrate deposition, microbial community composition, and enzyme activity in Northern hardwood forests. Soil Sci Soc Am J. 2004;68:132–138. [40]. Dick RP. A review: long term effects of agricultural systems on soil biochemical and microbial parameters. Agric Ecosyst Environ. 1992;40:25–36. [41]. Wilson HM, Al-Kaisi MM. Crop rotation and nitrogen fertilization effect on soil CO2 emissions in central Iowa. Appl Soil Ecol. 2008;39:264–270. [42]. Almaraz JJ, Zhou XM, Mabood F, Madramootoo C, Rochette P, et al. Greenhouse gas fluxes associated with soybean production under two tillage systems in southwestern Quebec. Soil Till Res. 2009;104:134–139. Diunduh dari sumber: 31/10/2012

Fang-Jie Zhao, Steve P. McGrath, and Andrew A. Meharg
Arsenic as a Food Chain Contaminant: Mechanisms of Plant Uptake and Metabolism and Mitigation Strategies Annual Review of Plant Biology. Vol. 61: (Volume publication date June 2010) Fang-Jie Zhao, Steve P. McGrath, and Andrew A. Meharg Tanaman padi sangat efisien mengakumulasikan As karena kondisi tergenang yang mengakibatkan mobilisasi arsenite, dan efisien menyerap arsenite melalui jalur transpor silikon. Diunduh dari sumber: …….. 31/10/2012

LAHAN SAWAH DI SEKITAR PEMUKIMAN
Mengindikasikan adanya konversi lahan sawah menjadi permukiman Foto: smno.lahansawah.madiun.jan2013

MK. MANAJEMEN SUMBERDAYA LAHAN & PENGEMBANGAN WILAYAH

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