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PENGELOLAAN AGROEKOSISTE M SAWAH Diabstraksikan oleh: Soemarno, FPUB Malang, 2012.

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Presentasi berjudul: "PENGELOLAAN AGROEKOSISTE M SAWAH Diabstraksikan oleh: Soemarno, FPUB Malang, 2012."— Transcript presentasi:

1 PENGELOLAAN AGROEKOSISTE M SAWAH Diabstraksikan oleh: Soemarno, FPUB Malang, 2012

2 SAWAH Sawah adalah lahan usaha pertanian yang secara fisik permukaan BIDANG OLAHNYA rata, dibatasi oleh pematang, serta dapat ditanami padi, palawija atau tanaman budidaya lainnya.lahanpertanianpematangpadipalawijatanaman budidaya 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.padiirigasimata airsungaihujan 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).

3 LAHAN SAWAH DI KELILINGI OLEH KEBUN CAMPURAN Lahan sawah adalah tanah yg dapat digenangi air dan mempertahankannya, dapat diratakan dan dibatasi dengan pematang Sawah berigasi (teknis, setengah teknis) Sawah tadah hujan Tindakan yg sangat penting dalam pengolahan tanah sawah adalah: PELUMPURAN (Proses terurainya agregat2 tanah menjadi partikel2 tanab yg lebih kecil & seragam, yg terjadi akibat adanya tenaga mekanis pd tanah yg mempunyai kandungan air tanah yg tinggi)

4 Surface water diversion impacts on farm income and sources of irrigation water: The case of the Grand Prairie in Arkansas J. HillJ. Hill, E. Wailes, M. Popp, J. Popp, J. Smartt, K. Young, and B. WatkinsE. WailesM. PoppJ. PoppJ. SmarttK. YoungB. Watkins Journal of Soil and Water Conservation July/August 2006 vol. 61 no. Alternative water conservation investment choices for the Grand Prairie Region of eastern Arkansas have been proposed. In particular, the cost-share and river water diversion components of the Grand Prairie Area Demonstration Project were analyzed in this study to determine their ramifications to area farms and water use. The cost-share alternative was deemed most effective given trade offs between ground and surface water use, income redistribution and farm income considerations. Effects of earlier reductions in rice production on the Arkansas economy may, however, justify water diversion and thus this study suggests the importance of further review of the Grand Prairie project.

5 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.

6 LAHAN SAWAH DI DATARAN TINGGI: TERAS BANGKU Ekosistem sawah dataran tinggi; Lahan sawah berupa teras-bangku, tebing teras diperkuat dengan rumput, sekelilingnya adalah agroforestry dengan campuran aneka tanaman pohon.

7 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.

8 Interaction of the social system with agricultural ecosystems after the Industrial Revolution

9 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

10 Coadaptation of modern social sytems and ecosystems

11 BUDIDAYA PADI Budidaya padi sawah (Ing. paddy atau paddy field), diduga dimulai dari daerah lembah Sungai Yangtse di Tiongkok.sawahYangtse Budidaya padi lahan kering, dikenal manusia lebih dahulu daripada budidaya padi sawah. Budidaya padi lahan rawa, dilakukan di beberapa tempat di Pulau Kalimantan.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.gogo rancahgoraLombok

12 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.

13 BUDIDAYA PADI SECARA INTENSIF 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

14 BUDIDAYA PADI SECARA INTENSIF PERMASALAHAN BUDIDAYA TANAMAN PADI 1.Penurunan kesehatan dan kesuburan tanah 2.Kecenderungan potensi padi untuk berproduksi lebih tinggi mandeg 3.Penggunaan unsur kimia anorganik dan pestisida sintesis meningkat 4.Perilaku petani sudah jauh dari kearifan dalam memanfaatkan potensi lokal

15 Irrational exploitation has brought about serious consequences causing severe soil erosion and loss of soil productivity in the red soil region of China. Different vegetation systems were thus established for soil conservation. Five systems—composed of eroded area (Er), bamboo (Bmb), Chinese fir (CF), citrus orchard (Ctr), and rice field (Rf)—were studied to monitor the status of phosphorus in their ecosystems. Generally, soil P was concentrated in the surface soil layer. The rank order for soil total phosphorus and microbial biomass phosphorus in the surface layer was: Rf > Ctr > Bmb > CF > Er and Bmb > CF > Ctr > Rf > Er, respectively. Among the established vegetation covers, external nutrient input had intensely contributed to the buildup of soil P status as systems receiving manure or fertilizer (Bmb, Ctr and Rf) and showed considerably higher P level in their profiles as compared with their forest counterpart (CF). The amount of total P lost from the soil by erosion depended mainly on the mass of soil eroded, mainly via particulate forms. The level of soil erosion was the highest in Er, followed by CF > Ctr > Bmb, and the amount of total P loss by soil erosion in descending order was the same: Er > CF > Ctr > Bmb. All these indicated that vegetation covers reduced soil erosion and nutrient loss significantly. Soil phosphorus status under restored plant covers established to control land degradation in the red soil region of South China Y. X. ChenY. X. Chen, Y. F. He, S. Kumar, Q. L. Fu, G. M. Tian, and Q. LinY. F. HeS. KumarQ. L. FuG. M. TianQ. Lin Journal of Soil and Water Conservation November/December 2002 vol. 57 no

16 BUDIDAYA PADI SECARA INTENSIF DASAR PEMIKIRAN METODE SRI 1.Tanaman Padi mempunyai potensi yang besar untuk menghasilkan produksi dalam taraf tinggi 2.Dapat dicapai dengan terpenuhinya kondisi yang optimal 3.Dicapai melalui proses pengelolaan tanah, tanaman dan air serta unsur agroekosistemnya 4.Terjadi kecenderungan penurunan produksi 5.Padi bukan tanaman air, tetapi padi tanaman yang membutuhkan air 6. Pada kondisi tanah tidak tergenang, akar akan tumbuh subur dan besar, sehingga dapat menyerap nutrisi yang banyak, sertra mendorong tumbuhnya ANAKAN yang optimal.

17 BUDIDAYA PADI SECARA INTENSIF PENYEBAB TERJADINYA PENURUNAN PRODUKSI PADI 1.Penurunan kesuburan tanah akibat penggunaan pupuk dan pestisida anorganik 2.Mikroba dalam tanah tidak bisa berfungsi 3.Aliran energi dari bawah ke atas permukaan tanah tidak seimbang 4.Suplay nutrisi dari tanah sangat kurang 5.Tanaman menunggu suplay makanan dari luar berupa pupuk sintesis 6.Penggunaan pupuk dan pestisida sintesis yang berlebihan mengakibatkan rantai makanan terputus 7.Musuh Alami hanya menunggu makanan dari keberadaan hama 8.Jenjang hirerkis Musuh Alami lebih tinggi maka hama akan berkembang lebih pesat

18 BUDIDAYA PADI SECARA INTENSIF CARA PANDANG KURANG ARIF 1.Orang beranggapan di sawah hanya ada tanaman dan hama 2.Untuk memenangkan persaingan hama harus dibunuh 3.Pestisida yang berkuasa untuk memusnahkan hama 4.Pestisida tidak bisa mengentaskan masalah karena hama 5.Hama menjadi kebal 6.Terjadi peledakan hama 7.Pencemaran lingkungan 8.Terbunuhnya jasad non sasaran 9.Pengurangan keragaman unsur hayati 10.Gangguan terhadap kesehatan manusia.

19 BUDIDAYA PADI SECARA INTENSIF

20 Conventional management practices for the rice-wheat rotation in Pakistan's Punjab have failed to improve crop yield, increase water and fertilizer use efficiencies, and decrease production costs enough to meet an ever-increasing food demand. New technologies such as no-till, laser leveling, and bed and furrow irrigation are being rapidly adopted by the farming community, but without adequate scientific information. Therefore, those practices were evaluated on 71 farms within four representative sites. Land preparation/sowing costs, water savings, use of fertilizers, soil salinity, and crop yield were evaluated. Land preparation and sowing cost on no- till fields was significantly less than on tilled fields. Highest yields were obtained on laser-leveled fields, followed by no-till, bed and furrow fields. Water and nitrogen use efficiencies were much higher on fields with bed and furrow irrigation as compared to the conventional fields. Although all the new technologies were economically feasible, we conclude that no-till was the best option for the farmers. Soil management strategies for rice-wheat rotations in Pakistan's Punjab M.A. KahlownM.A. Kahlown, M. Azam, and W.D. KemperM. AzamW.D. Kemper Journal of Soil and Water Conservation January/February 2006 vol. 61 no

21 BUDIDAYA PADI SECARA INTENSIF SRI Di Indonesia antara lain oleh Pak Engkus Kuswara dan Pak Alik Sutaryat (Tahun 1999) Yang mereka terapkan adalah : Tanam Tunggal Dan Dangkal Umur Semai Kurang 15 Hari Penanaman cepat kurang 15 Menit Pupuk Organik

22 BUDIDAYA PADI SECARA INTENSIF METODOLOGI SRI ADALAH : 1.Tanaman Hemat Air (Max 2 Cm = Macak-macak dan juga ada periode pengeringan sampai tanah pecah-pecah) 2.Hemat Biaya (butuh bibit 5 Kg/Ha, Tidak butuh biaya Pencabutan, Pemindahan, Irit tenaga tanam, dll) 3.Hemat Waktu (bibit ditanam muda HSS dengan jarak tanam lebar dan Panen lebih awal sekitar 10 – 14 hari) 4.Produksi Bisa Mencapai Ton/Ha.

23 PENGARUH PENGGENANGAN AIR TERHADAP PERTUMBUHAN PADI 1.Merangsang pertumbuhan memanjang tanaman, menghasilkan lebih banyak jerami 2.Menghambat pertumbuhan anakan/tunas 3.Tanaman kurang dapat mengambil unsur hara yang dibutuhkan 4.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

24 PRINSIP SRI 1.Pengolahan tanah dan pemupukan kompos organik 2.Benih bermutu dan ditanam muda 3.Benih ditanam tunggal dan langsung 4.Jarak tanam Lebar 5.Pemupukan tidak dengan pupuk sintesis 6.Pengelolaan air yang macak-macak dan bersamaan dengan penyiangan 7.PHT tidak memakai pestisida sintesis

25 UJI BENIH BERMUTU DENGAN LARUTAN GARAM Caranya : 1.Siapkan ember atau panci atau wadah lain beriisi air 2.Masukan garam aduk-aduk sampai larut, 3.Masukan telur ayam mentah kedalam larutan garam tersebut, bila telur masih tenggelam maka perlu penambahan garam. 4.Pemberian garam dianggap cukup apabila telur sudah mengapung. 5.Masukan benih yang sudah disiapkan kedalam larutan tersebut. 6.Benih yang tenggelam yang digunakan sebagai benih yang akan ditanam.

26 PERENDAMAN DAN PEMERAMAN BENIH 1.BENIH DIRENDAM, Setelah diuji, benih direndam dengan mempergunakan air bersih dengan tujuan mempercepat perkecambahan selama 24 – 48 jam. 2.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.

27 CARA MEMBUAT PERSEMAIAN 1.Campurkan Tanah dan kompos 1 : 1 2.Masukan campuran tanah dan kompos ke dalam baki atau pipiti yang dilapisi daun pisang 3.Taburkan benih ke dalam nampan 4.Tutup dengan jerami atau kompos

28 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 )

29 KETERBATASAN S R I 1.Membutuhkan tenaga kerja lebih banyak (pada awalnya) 2.Perlu drainase untuk membuang kelebihan air 3.Lebih banyak waktu untuk untuk mengatur pengairan 4.Lebih banyak waktu dan tenaga kerja untuk penyiangan 5.Pembuatan kompos

30 Hama-hama penting tanaman padi Penggerek batang padi putihPenggerek batang padi putih ("sundep", Scirpophaga innotata) Penggerek batang padi kuningPenggerek batang padi kuning (S. incertulas) Wereng batang punggung putihWereng batang punggung putih (Sogatella furcifera) Wereng coklatWereng coklat (Nilaparvata lugens) Wereng hijauWereng hijau (Nephotettix impicticeps) Lembing hijauLembing hijau (Nezara viridula) Walang sangitWalang sangit (Leptocorisa oratorius) GanjurGanjur (Pachydiplosis oryzae) Lalat bibitLalat bibit (Arterigona exigua) Ulat tentaraUlat tentara/Ulat grayak (Spodoptera litura dan S. exigua) Tikus sawahTikus sawah (Rattus argentiventer)

31 Penyakit-penyakit penting 1.Blas (Pyricularia oryzae, P. grisea) 2.Hawar daun bakteri ("kresek", Xanthomonas oryzae pv. oryzae) 3.Bercak coklat daun (Helmintosporium oryzae). 4.Garis coklat daun (Cercospora oryzae) 5.Busuk pelepah daun (Rhizoctonia sp) 6.Penyakit fusarium (Fusarium moniliforme) 7.Penyakit noda (Ustilaginoidea virens) 8.Hawar daun (Xanthomonas campestris) 9.Penyakit bakteri daun bergaris (Translucens) 10.Penyakit kerdil (Nilaparvata lugens) 11.Penyakit tungro (Nephotettix impicticeps)

32 PENGOLAHAN TANAH SAWAH SECARA TRADISIONAL Lahan sawah digarap untuk menanam padi. Musim tanam padi dalam setahun bisa dilakukan 3 kali tanam, hal ini dikarenakan pasokan air yang cukup untuk area pesawahan.

33 At the 2011 Annual Meeting of the Soil and Water Conservation Society, the Executive Director Jim Gulliford announced a new Position Statement on Climate Change and Soil and Water Conservation: “The Soil and Water Conservation Society finds that soil and water conservation practices can play a major role in the mitigation of agriculture's contribution to greenhouse gas emissions and adaptation to changes in seasonal precipitation and temperature patterns” (SWCS 2011). The National Wildlife Federation agreed with this position in the recent publication, Future Friendly Farming: Seven Agricultural Practices to Sustain People and the Environment (Stockwell and Bitan 2011). We found that the seven practices discussed in this publication also improve farmer profitability thanks to modern tools and knowledge (Stockwell and Bitan 2011). Adoption of these and other soil and water conservation practices is in relatively early phases. Early innovators have begun incorporating these practices, but going from minimal adoption rates to broad or diffuse implementation will require additional information to not only answer farmers' questions, but to give them the information and encouragement to implement these practices. This article shares the experience of four early adopters of innovative practices. We hope these stories will help answer every farmer's first question… Understanding opportunities and increasing implementation of climate friendly conservation Ryan StockwellRyan Stockwell and Eliav BitanEliav Bitan Journal of Soil and Water Conservation May/June 2012 vol. 67 no. 3 67A-69A

34 HUBUNGAN AIR-TANAH-TANAMAN

35 PEMBUATAN & PEMELIHARAAN PESEMAIAN Cara pengolahan sawah hampir tak berubah dari abad ke abad. Peralatan yang dipakai hampir sama dengan peralatan yang dipakai nenek moyang mereka. Ada beberapa proses pengolahan sawah, seperti menyemai, membajak, meratakan dan menanam.

36 The goal of the study was to determine if pesticide use in rice production in Arkansas was leading to environmental problems. Four sites on each of four small rivers in the rice growing area in eastern Arkansas were chosen for sampling from spring to mid-August each year. Typically, 9 to 12 compounds were chosen based on recommendations of scientists involved in rice production. The specific compounds may have changed, but the constant was that there was a reasonable chance of the compounds being present. For this study, only concentrations above 2 μg L -1 (2 ppb) were used to determine if nontarget species were being harmed. Eliminating low concentrations makes it easier to determine meaningful detections on consecutive sampling dates, frequency of detections, and multiple detections per sample. Although glyphosate is used in rice production, it was not included in the study because it is also used in other crops, especially soybean, so results could not be related to rice production. Most detections occurred in May, June, and July, when most compounds are applied. The probability of finding compounds in the L'Anguille and Cache rivers was 5 to 10 times higher than in the St. Francis River or Lagrue Bayou. Does pesticide use in rice production in Arkansas lead to environmental problems? John Mattice Journal of Soil and Water Conservation March/April 2010 vol. 65 no. 2 55A

37 PADI JENIS UNGGUL Padi Unggul Dewi Sri Padi Unggul Merdeka

38 PENYIANGAN TANAMAN PADI MUDA Apa tujuan penyiangan tanaman padi sawah ini?

39 IRIGASI Irigasi merupakan upaya yang dilakukan manusia untuk mengairi lahan pertanian.lahan pertanian Ada banyak model irigasi yang dapat dilakukan manusia. Pada zaman dahulu, jika persediaan air melimpah karena tempat yang dekat dengan sungai atau sumber mata air, maka irigasi dilakukan dengan mengalirkan air tersebut ke lahan pertanian.sungai Irigasi juga dilakukan dengan membawa air dengan menggunakan wadah kemudian menuangkan pada tanaman satu per satu. Untuk irigasi dengan model seperti ini di Indonesia biasa disebut menyiram.

40 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. bendung 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.

41 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.

42 Irigasi dengan Penyemprotan Penyemprotan biasanya dipakai penyemprot air atau sprinkle. Air yang disemprot akan seperti kabut, sehingga tanaman mendapat air dari atas, daun akan basah lebih dahulu, kemudian menetes ke akar.

43 Irigasi Tradisional dengan Ember Di sini diperlukan tenaga kerja secara perorangan yang banyak sekali. Di samping itu juga pemborosan tenaga kerja yang harus menenteng ember.

44 Irigasi Pompa Air Air diambil dari sumur dalam dan dinaikkan melalui pompa air, kemudian dialirkan dengan berbagai cara, misalnya dengan pipa atau saluran. Pada musim kemarau irigasi ini dapat terus mengairi sawah.

45 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.

46 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.[3]

47 CARA MEMUPUK PADI SAWAH SECARA BENAR

48 Precision land leveling can expose subsurface soil layers that have elevated levels of exchangeable sodium and can deposit this sodium-laden material on the original soil surface in other parts of the field. Results from two case studies where a geographic information system (GIS) and global positioning system (GPS) were utilized to assist with land-leveling decisions for soils containing elevated soluble salts and sodium are discussed. In both cases, the spatial distribution of Na, exchangeable sodium percentage (ESP), and electrical conductivity (EC) were overlain with maps depicting the pattern of removal and re-deposition of soil. From this analysis, an estimate of the potential sodium hazard that might result from precision grading was determined. Decisions derived from traditional, composite sampling were compared to decisions made with site-specific technology. The spatial technology approach utilized in this work provided decision makers with reasonable assurance about their precision grading decisions apriori. Utilizing spatial technology as a decision-assist tool for precision grading of salt-affected soils M. B. DanielsM. B. Daniels, S. L. Chapman, and W. TeagueS. L. ChapmanW. Teague Journal of Soil and Water Conservation May/June 2002 vol. 57 no

49 TEKNOLOGI APLIKASI PUPUK PADI SAWAH Pemupukan Berimbang Tanaman Padi Sawah Untuk Persemaian : Urea 1 Genggam untuk satu M² persemaian SP 36 1 Genggam untuk satu M² persemaian KCl = 1,5 Kg / Piring Upahan ZA = 1,5 Kg / Piring Upahan Pupuk I (Pupuk Dasar) Diberikan sebelum atau sesudah tanam Urea = 1,5 Kg / Piring Upahan SP 36 = 3 Kg / Piring Upahan KCl = 1,5 Kg / Piring Upahan ZA = 1 Kg / Piring Upahan Pupuk II (Pupuk Susulan I) Diberikan waktu siang pertama Urea = 2 Kg / Piring Upahan SP 36 = - Kg / Piring Upahan KCl = - Kg / Piring Upahan ZA = 0,5 Kg / Piring Upahan Pupuk III (Pupuk Susulan II) Diberikan waktu siang kedua Urea = 1,5 Kg / Piring Upahan SP 36 = - Kg / Piring Upahan KCl = - Kg / Piring Upahan ZA = - Kg / Piring Upahan

50 SISTEM TANAH-AIR-TANAMAN PADI SAWAH

51 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 nameCorresponding value Water height (cm) pF (-) Bar (bar) Pascal (Pa) Kilo Pascal (kPa) Mega Pascal (MPa)

52 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

53 Potential = 0 Potential is + Potential = - Potential = 0 Potential = +

54 There is increased pressure on the water resources of the southeastern United States due to the rapidly growing population of the region. This pressure is further exacerbated by the severe seasonal to interannual climate variability this region experiences, most of which has been attributed to the El Niño Southern Oscillation (ENSO). Understanding the regional impacts of ENSO on precipitation and streamflow is a valuable tool for water resource managers in the region. This study was undertaken to develop a clear picture of the effect of ENSO on observed precipitation and streamflow anomalies in Alabama to help managers in the state with decision making. The effect of ENSO on precipitation in eight climate divisions of Alabama was assessed using 59 years (1950 to 2008) of monthly historical data. In addition, eight unimpaired streams (one in each climate division) were selected to study the relationship between ENSO and streamflow. Results indicate a significant relationship between ENSO and precipitation as well as between ENSO and streamflow. However, different parts of the state respond differently to ENSO. For precipitation, it was found that the relationship is significant during winter months with dry conditions being associated with La Niña in the southern climate divisions. A fairly strong relationship was also found during other months. Streamflows show high variability and positive correlation during winter months in the southern climate divisions. The results obtained can provide a basis for water resource managers in Alabama to incorporate climate variability caused by ENSO in their decision making related to soil and water conservation. Quantification of El Niño Southern Oscillation impact on precipitation and streamflows for improved management of water resources in Alabama V. ShardaV. Sharda, P. Srivastava, K. Ingram, M. Chelliah and L. KalinP. SrivastavaK. IngramM. ChelliahL. Kalin Journal of Soil and Water Conservation May/June 2012 vol. 67 no

55 Water potential in the flooded rice soil The unsaturated soil “pulls” at the water and potential is negative

56 When a paddy rice field falls dry, the soil water potential becomes negative and decreases Positive water potential Negative water potential

57 Potential during the growing season in an aerobic soil (aerobic rice, Changping, China, 2002)

58 Each soil type has a specific relationship between the content and the potential of water: the pF curve Soil water tension (pF= log(h)) Soil water content (cm 3 cm -3 ) Clay Sand Tension (pF ) Content (cm 3 water cm -3 soil)

59 A clay soil stores much water, but at a high tension, so it is difficult for the roots to extract A sandy soil holds little water, but at a low tension, so it is easy for the roots to extract A medium-textured, loamy soil, holds intermediate levels of water at intermediate tensions, so there is relatively much water for extraction by roots No issue for flooded rice soil, but becomes an issue when a soil falls dry during a dry spell

60 Example of potentials in soil-plant-atmosphere system Potentials drop with each added resistance

61 Potential of water in the atmosphere (above leaves) drives the potential transpiration rate, which is f(radiation, wind speed, vapor pressure, temperature). A hot sunny day => pulls hard at water from plant Potential of water in the soil is determined by the soil properties (texture, SOM,..) and water content: Clay soil pulls hard at water Sand soil pulls softly at water Much water: high potential Little water: low potential A dry clay soil pulls hard at water (difficult to take up by roots)

62 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: Reduced transpiration Reduced photosynthesis Reduced leaf area expansion Leaf rolling Accelerated leaf death Spikelet sterility CEKAMAN KEKERINGAN

63 Reduced transpiration as function of soil water tension (IR72) leaf (T act /T pot ) Soil water tension

64 Link between transpiration and photosynthesis

65 Rolled leaves => less canopy photosynthesis Leaf rolling

66 Denitrification of nitrate in the soil can be a mechanism of significant loss of fertilizer and soil nitrogen, but it can also serve to remove excess NO 3 that is leached below the root zone. Inappropriate management of irrigation water and fertilizer N in irrigated corn has resulted in leaching of excess N from the rooting zone and contamination of groundwater and also has contributed to the increasing concentration of N 2 O in the atmosphere. Denitrification can be both microbial and chemical, but the microbial process dominates in most soils through a stepwise reduction of NO 3 to N 2. Soil atmosphere O 2 concentration, which is regulated by soil water content interactively with soil texture and microbial respiration, is the main controller of the process. The oxygen consumption rate depends on the amount of easily degradable organic C compounds and the interplay of water and carbon in developing in the soil reduced oxic conditions, which regulate not only the amount of total denitrification but also the ratio of N 2 O to N 2 produced. Appropriate management of nutrient input, relative to crop demand and soil water status, can limit nitrogen loss from denitrification. This paper describes the role of denitrification in the nitrogen economy of crop production and the environment, describes the process involved, and presents suggestions for limiting N loss caused by denitrification. Managing soil denitrification A. R. MosierA. R. Mosier, J. W. DoranJ. W. Doran, and J. R. Freney Journal of Soil and Water Conservation November/December 2002 vol. 57 no

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

68 Rice is a major cash crop for eastern Arkansas and generally involves intensive cultivation. Sediment is the primary pollutant identified for most eastern Arkansas waterways, and conservation practices like no-till are commonly recommended as remedial mechanisms. The profitability of no-till rice has been investigated, but the main emphasis has been on comparing mean returns of no-till to conventional till without consideration for return variability. Profitability in these studies is also evaluated from the prospective of the producer only, despite the fact that most cropland is owned by someone other than the producer. This study evaluates the profitability and risk efficiency of no-till management in Arkansas rice production from both the perspective of the tenant and the landlord using simulation and stochastic efficiency with respect to a function. Crop yields and prices are simulated for a typical two-year rice-soybean rotation, and tenant and landlord net return distributions are constructed for popular rental arrangements used in eastern Arkansas rice production. The results indicate that both the tenant and the landlord can benefit monetarily from no-till management. Risk-neutral and risk-averse tenants would both benefit from no-till management as no-till increases mean (expected) returns for risk-neutral tenants and results in large risk premiums over conventional till for risk-averse tenants. Risk-neutral landlords would be indifferent between either no-till or conventional till management because mean returns are essentially the same for both tillage methods. Risk-averse landlords would have a slight preference for no-till, since no-till risk premiums tend to be positive with increasing levels of risk aversion. However, no-till risk premiums are modest for risk-averse landlords, implying that risk would play less of a role for the landlord than for the tenant when considering the use of no-till management on rented land. An economic risk analysis of no-till management and rental arrangements in Arkansas rice production K.B. WatkinsK.B. Watkins, J.L. Hill, and M.M. AndersJ.L. HillM.M. Anders Journal of Soil and Water Conservation July/August 2008 vol. 63 no

69 Accelerated leaf death Dead leaves => less canopy photosynthesis

70 Leaf expansion, Leaf death Leaf rolling, Spikelet sterility Leaf photosynthesis, transpiration Summary effects of soil water tension; IR72 photosynthesis

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

72 Effect of timing of drought: most sensitive at flowering O’Toole, 1984

73 Moderate drought in early growth stages

74 The ability of water resources to support aquatic life and human needs depends, in part, on reducing nonpoint source pollution amid contemporary agricultural practices. Winter retention of shallow water on rice and other agricultural fields is an accepted management practice for wildlife conservation; however, soil and water conservation benefits are not well documented. We evaluated the ability of four post-harvest ricefield treatment combinations (stubble-flooded, stubble-open, disked-flooded and disked-open) to abate nonpoint source exports into watersheds of the Mississippi Alluvial Valley. Total suspended solid exports were 1,121 kg ha -1 (1,000 lb ac -1 ) from disked-open fields where rice stubble was disked after harvest and fields were allowed to drain, compared with 35 kg ha -1 (31 lb ac -1 ) from stubble-flooded fields where stubble was left standing after harvest and fields captured rainfall from November 1 to March 1. Estimates of total suspended solid exports from ricefields based on Landsat imagery and USDA crop data are 0.43 and 0.40 Mg km -2 day -1 in the Big Sunflower and L'Anguille watersheds, respectively. Estimated reductions in total suspended solid exports from ricefields into the Big Sunflower and L'Anguille watersheds range from 26% to 64% under hypothetical scenarios in which 65% to 100% of the rice production area is managed to capture winter rainfall. Winter ricefield management reduced nonpoint source export by decreasing concentrations of solids and nutrients in, and reducing runoff volume from, ricefields in the Mississippi Alluvial Valley. Soil and nutrient retention in winter-flooded ricefields with implications for watershed management S.W. ManleyS.W. Manley, R.M. Kaminski, P.B. Rodrigue, J.C. Dewey, S.H. Schoenholtz, P.D. Gerard and K.J. ReineckeR.M. KaminskiP.B. RodrigueJ.C. DeweyS.H. SchoenholtzP.D. GerardK.J. Reinecke Journal of Soil and Water Conservation May/June 2009 vol. 64 no

75 Leaf rolling in early growth stages

76 Climate change, in combination with the expanding human population, presents a formidable food security challenge: how will we feed a world population that is expected to grow by an additional 2.4 billion people by 2050? Population growth and the dynamics of climate change will also exacerbate other issues, such as desertification, deforestation, erosion, degradation of water quality, and depletion of water resources, further complicating the challenge of food security. These factors, together with the fact that energy prices may increase in the future, which will increase the cost of agricultural inputs, such as fertilizer and fuel, make the future of food security a major concern. Additionally, it has been reported that climate change can increase potential erosion rates, which can lower agricultural productivity by 10% to 20% (or more in extreme cases). Climate change could contribute to higher temperatures and evapotranspiration and lower precipitation across some regions. This will add additional pressure to draw irrigation water from some already overexploited aquifers, where the rate of water recharge is lower than the withdrawal rates. These and other water issues exacerbated by climate change present a serious concern because, on average, irrigated system yields are frequently double those of nonirrigated systems. Conservation practices to mitigate and adapt to climate change Jorge A. DelgadoJorge A. Delgado, Peter M. Groffman, Mark A. Nearing, Tom Goddard,Peter M. GroffmanMark A. NearingTom Goddard Don ReicoskyDon Reicosky, Rattan Lal, Newell R. Kitchen, Charles W. Rice,Rattan LalNewell R. KitchenCharles W. Rice Dan ToweryDan Towery and Paul SalonPaul Salon Journal of Soil and Water Conservation July/August 2011 vol. 66 no A-129A

77 Severe drought in early growth stages

78 Severe drought in upper field near Roi Et, Oct. 2004

79 The ability of water resources to support aquatic life and human needs depends, in part, on reducing nonpoint source pollution amid contemporary agricultural practices. Winter retention of shallow water on rice and other agricultural fields is an accepted management practice for wildlife conservation; however, soil and water conservation benefits are not well documented. We evaluated the ability of four post-harvest ricefield treatment combinations (stubble-flooded, stubble-open, disked-flooded and disked-open) to abate nonpoint source exports into watersheds of the Mississippi Alluvial Valley. Total suspended solid exports were 1,121 kg ha -1 (1,000 lb ac -1 ) from disked-open fields where rice stubble was disked after harvest and fields were allowed to drain, compared with 35 kg ha -1 (31 lb ac -1 ) from stubble-flooded fields where stubble was left standing after harvest and fields captured rainfall from November 1 to March 1. Estimates of total suspended solid exports from ricefields based on Landsat imagery and USDA crop data are 0.43 and 0.40 Mg km -2 day -1 in the Big Sunflower and L'Anguille watersheds, respectively. Estimated reductions in total suspended solid exports from ricefields into the Big Sunflower and L'Anguille watersheds range from 26% to 64% under hypothetical scenarios in which 65% to 100% of the rice production area is managed to capture winter rainfall. Winter ricefield management reduced nonpoint source export by decreasing concentrations of solids and nutrients in, and reducing runoff volume from, ricefields in the Mississippi Alluvial Valley. Soil and nutrient retention in winter-flooded ricefields with implications for watershed management S.W. ManleyS.W. Manley, R.M. Kaminski, P.B. Rodrigue, J.C. Dewey, S.H. Schoenholtz, P.D. Gerard and K.J. ReineckeR.M. KaminskiP.B. RodrigueJ.C. DeweyS.H. SchoenholtzP.D. GerardK.J. Reinecke Journal of Soil and Water Conservation May/June 2009 vol. 64 no

80 SMJRD15 Severe drought

81 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.

82 Small-Scale Agriculture in Southeast Asia Gerald G. Marten In M.A. Altieri and S. Hecht (eds.), Agroecology and Small Farm Development (CRC Press. 1990), p Terraced Rice Paddies Paddy field preparation begins in October by using a spade to turn over weeds and rice stalks from the previous harvest, trampling them into the mud to rot. The field is then harrowed. A man stands on the spike harrowing board as a buffalo pulls it through the mud, scattering decaying rice stalks so they cannot take root. The field is then flooded so the farmers can level the mud with the palms of their hands. Communal labor groups clean out irrigation canals at this time. Mud from the paddy fields is packed on top of the bunds surrounding the fields and against all paddy field margins to plug holes and improve the moisture seal of the field. Taro is planted along the terrace top or laced on the rims of the paddy field. Beans or sweet potatoes may be planted at the sides of the bunds. A few weeks later it is time to weed the empty paddy fields again. The stone walls of the terraces are also weeded (with a trowel), and rat holes are stuffed with weeds. Weeds are collected from slopes immediately above the field, thrown into the fields and trampled into the mud. Pig manure compost is brought from the village in baskets and mixed into the mud. Seedbeds are established in paddy fields with a history of high fertility and a water supply that will not be interrupted by paddy field preparation and cleaning of irrigation canals. A small section of a field is blocked off for the seedbed, so it can be drained even when the rest of the field is flooded. The seedbed is strewn with rice husks, dried bean pods, and sunflower leaves and stems, which are trampled into the mud to rot. Rice pannicles with the largest quantity of grain are chosen for the seedbed during the previous harvest. Seedbeds are planted in November to January; pannicles about a foot in length are pushed into the mud and bent so the rice grains lie flat on the ground. Water is temporarily drained from the seedbed so the pannicles do not float. The seedbed is flooded with 1 to 2 cm of water, which discourages animals such as rats and birds from eating the seedlings. If the seedlings do not appear healthy, ashes are spread around them to increase the fertility of the bed.

83 Small-Scale Agriculture in Southeast Asia Gerald G. Marten In M.A. Altieri and S. Hecht (eds.), Agroecology and Small Farm Development (CRC Press. 1990), p Terraced Rice Paddies Seedlings are ready for transplanting in February and March. In preparation, paddy fields receive their final smoothing, kneading, and leveling. The earth is reworked with a harrow or spading fork and subjected to another puddling with the feet. The field is drained, and the top 12 to 15 cm of soil is given a final working and leveling either with the hands or with a board that is dragged around the field by a buffalo. Farmers believe that mud in shallower water is warmer and enhances growth and flowering of the rice plants. Women do the transplanting in groups. While some plaster mud on the margins of the fields, others bring bundles of five or six pannicles (approximately 100 to 150 seedlings) from the seedbeds. (Seedlings from seedbeds with nematodes are not used.) Different rice varieties are planted in different fields. For example, one variety does best in paddy fields that were drained during the fallow while another variety does better in fields that could not be drained. The women tear the top leaves off the seedlings as they plant them. This is said to make the rice plant mature faster, perhaps by reducing transpiration and making the seedlings more resistant to drought. Shorter seedlings are also more resistant to being blown over by wind. The seedlings are pushed into the mud 10 to 15 cm apart with only the top 10 to 12 cm above the surface. High tillering varieties and high fertility paddies are planted less densely (i.e., 15 cm spacing). Seedlings that die after transplanting are replaced by seedlings from other parts of the field or from other fields. A continuous supply of water is essential once the rice is transplanted. There is a village system of water rotation among the fields, but each household finds it advisable to oversee personally the delivery of water to its fields, in order to ensure its fair share. Disputes may arise and tempers wear thin as the season progresses and the supply of water diminishes.

84 Small-Scale Agriculture in Southeast Asia Gerald G. Marten In M.A. Altieri and S. Hecht (eds.), Agroecology and Small Farm Development (CRC Press. 1990), p Rainfed Upland Fields Upland fields are typically a mixture of interplanted crops of various heights. The lowest layer consists of creeping plants such as peanuts, soybeans, cucumbers, and melon. Above them are taller vegetables such as chili peppers and eggplant. The top layer is occupied by maize, tobacco, cassava, or leguminous vines (e.g., wingbean or longbean) supported by bamboo poles. The field may also contain scattered fruit or other trees (e.g., Albizia). Field preparation is in August. Farmers first weed the field and till the soil with a hoe. They cut down any unwanted perennial vegetation and leave the slash to dry. Litter, leaves, and slash are burned in small piles at the end of August. Different fields may contain completely different groups of crops, but each consists of crops which the farmers have found by experience to be compatible with one another. For example, bananas, sweet potatoes, peanuts, corn, and beans can be grown together, but cassava cannot be included because it will crowd out the other crops.

85 Small-Scale Agriculture in Southeast Asia Gerald G. Marten In M.A. Altieri and S. Hecht (eds.), Agroecology and Small Farm Development (CRC Press. 1990), p Example of a homegarden layout in the uplands of West Java. (From Christanty, L., Abdoellah, O. S., Marten, G. G., and Iskandar, J., in Traditional Agriculture in Southeast Asia, Marten, G. G., Ed., Westview Press, Boulder, CO, 1986, 132.)

86 Lahan sawah berteras untuk konservasi tanah dan air

87 Soil and nutrient retention in winter-flooded ricefields with implications for watershed management S.W. ManleyS.W. Manley, R.M. Kaminski, P.B. Rodrigue, J.C. Dewey, S.H. Schoenholtz, P.D. Gerard and K.J. ReineckeR.M. KaminskiP.B. RodrigueJ.C. DeweyS.H. SchoenholtzP.D. GerardK.J. Reinecke Journal of Soil and Water Conservation May/June 2009 vol. 64 no The ability of water resources to support aquatic life and human needs depends, in part, on reducing nonpoint source pollution amid contemporary agricultural practices. Winter retention of shallow water on rice and other agricultural fields is an accepted management practice for wildlife conservation; however, soil and water conservation benefits are not well documented. We evaluated the ability of four post-harvest ricefield treatment combinations (stubble-flooded, stubble-open, disked-flooded and disked-open) to abate nonpoint source exports into watersheds of the Mississippi Alluvial Valley. Total suspended solid exports were 1,121 kg ha -1 (1,000 lb ac - 1 ) from disked-open fields where rice stubble was disked after harvest and fields were allowed to drain, compared with 35 kg ha -1 (31 lb ac -1 ) from stubble-flooded fields where stubble was left standing after harvest and fields captured rainfall from November 1 to March 1. Estimates of total suspended solid exports from ricefields based on Landsat imagery and USDA crop data are 0.43 and 0.40 Mg km -2 day -1 in the Big Sunflower and L'Anguille watersheds, respectively. Estimated reductions in total suspended solid exports from ricefields into the Big Sunflower and L'Anguille watersheds range from 26% to 64% under hypothetical scenarios in which 65% to 100% of the rice production area is managed to capture winter rainfall. Winter ricefield management reduced nonpoint source export by decreasing concentrations of solids and nutrients in, and reducing runoff volume from, ricefields in the Mississippi Alluvial Valley.

88 An economic risk analysis of no-till management and rental arrangements in Arkansas rice production K.B. WatkinsK.B. Watkins, J.L. Hill, and M.M. AndersJ.L. HillM.M. Anders Journal of Soil and Water Conservation July/August 2008 vol. 63 no Rice is a major cash crop for eastern Arkansas and generally involves intensive cultivation. Sediment is the primary pollutant identified for most eastern Arkansas waterways, and conservation practices like no-till are commonly recommended as remedial mechanisms. The profitability of no-till rice has been investigated, but the main emphasis has been on comparing mean returns of no-till to conventional till without consideration for return variability. Profitability in these studies is also evaluated from the prospective of the producer only, despite the fact that most cropland is owned by someone other than the producer. This study evaluates the profitability and risk efficiency of no-till management in Arkansas rice production from both the perspective of the tenant and the landlord using simulation and stochastic efficiency with respect to a function. Crop yields and prices are simulated for a typical two-year rice-soybean rotation, and tenant and landlord net return distributions are constructed for popular rental arrangements used in eastern Arkansas rice production. The results indicate that both the tenant and the landlord can benefit monetarily from no-till management. Risk- neutral and risk-averse tenants would both benefit from no-till management as no-till increases mean (expected) returns for risk-neutral tenants and results in large risk premiums over conventional till for risk- averse tenants. Risk-neutral landlords would be indifferent between either no-till or conventional till management because mean returns are essentially the same for both tillage methods. Risk-averse landlords would have a slight preference for no-till, since no-till risk premiums tend to be positive with increasing levels of risk aversion. However, no-till risk premiums are modest for risk-averse landlords, implying that risk would play less of a role for the landlord than for the tenant when considering the use of no-till management on rented land.

89 The ability of water resources to support aquatic life and human needs depends, in part, on reducing nonpoint source pollution amid contemporary agricultural practices. Winter retention of shallow water on rice and other agricultural fields is an accepted management practice for wildlife conservation; however, soil and water conservation benefits are not well documented. We evaluated the ability of four post-harvest ricefield treatment combinations (stubble-flooded, stubble-open, disked-flooded and disked-open) to abate nonpoint source exports into watersheds of the Mississippi Alluvial Valley. Total suspended solid exports were 1,121 kg ha -1 (1,000 lb ac -1 ) from disked-open fields where rice stubble was disked after harvest and fields were allowed to drain, compared with 35 kg ha -1 (31 lb ac -1 ) from stubble-flooded fields where stubble was left standing after harvest and fields captured rainfall from November 1 to March 1. Estimates of total suspended solid exports from ricefields based on Landsat imagery and USDA crop data are 0.43 and 0.40 Mg km -2 day -1 in the Big Sunflower and L'Anguille watersheds, respectively. Estimated reductions in total suspended solid exports from ricefields into the Big Sunflower and L'Anguille watersheds range from 26% to 64% under hypothetical scenarios in which 65% to 100% of the rice production area is managed to capture winter rainfall. Winter ricefield management reduced nonpoint source export by decreasing concentrations of solids and nutrients in, and reducing runoff volume from, ricefields in the Mississippi Alluvial Valley. Soil and nutrient retention in winter-flooded ricefields with implications for watershed management S.W. ManleyS.W. Manley, R.M. Kaminski, P.B. Rodrigue, J.C. Dewey, S.H. Schoenholtz, P.D. Gerard and K.J. ReineckeR.M. KaminskiP.B. RodrigueJ.C. DeweyS.H. SchoenholtzP.D. GerardK.J. Reinecke Journal of Soil and Water Conservation May/June 2009 vol. 64 no


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