EVALUASI PRODUKTIVITAS TANAH – TANAMAN

EVALUASI PRODUKTIVITAS TANAH – TANAMAN
Mk. Stela-smno.fpub.jun2013

CPI = CROP PRODUCTIVITY INDEX RATING
Nilai CPI menyediakan informasi ranking relatif tanah-tanah berdasarkan potensinya untuk produksi tanaman. Indeks ini dapat digunakan untuk menilai potensial-hasil tanaman pada suatu tanah dibandingkan tanah lainnya selama periode waktu tertentu. Sumber:.

CPI = CROP PRODUCTIVITY INDEX RATING Productivity Index (PI)
Model Productivity index (PI) merupakan suatu ukuran yang diturunkan dari produktivitas tanah. Asumsi mendasar dari model PI ini adalah bahwa hasil tanaman merupakan fungsi dari pertumbuhan akar, yang selanjutnya pertumbuhan akar ini dikendalikan oleh kondisi lingkungan tanah. Sumber:.

Indeks ini melingkupi semua tanaman, kecuali tanaman pakan ternak.
CPI = CROP PRODUCTIVITY INDEX RATING CPI menunjukkan produksi pertanian setiap tahun, relatif terhadap tahaun dasar tertentu (misalnya ). Indeks ini melingkupi semua tanaman, kecuali tanaman pakan ternak. Regional and income group aggregates for the FAO's production indexes are calculated from the underlying values in international dollars, normalized to the base period Sumber:.

Indeks produksi tanaman merupakan indikator tingkat produksi tanaman. Indeks ini mencerminkan perubahan volume produksi dan siklus produksi. The index covers 21 major crops and 20 vegetables and fruits, accounting for 67.7% of total value of agricultural produc ts. Monthly index is calculated, then quarterly and yearly indices are derived as the average of monthly series. Data can be dated back to 1988. Sumber:.

Formula yang digunakan adalah sbb:
CPI = CROP PRODUCTIVITY INDEX RATING Data sekunder dari instansi resmi pemerintah dapat digunakan untuk perhitungan. Indeks dihitung dnegan formula Laspeyres, tahun dasarnya misalnya 1988. Produksi bulanan tahun dasar (1988) merupakan rata-rata total-produksi setiap tanaman selama seluruh tahun. Weight applied to each product is the relative value-added of each product to that of the entire agricul tural sector as appeared in the national account disseminated by the National Economic and Social Development Board (NESDB). Formula yang digunakan adalah sbb: Sumber:.

dimana = CPI untuk bulan t, = Kuantitas produk tanaman i bulan t pada tahun sedang berjalan = Kuantitas produk tanaman i pada tahun dasar 1988 = Bobot produk i pada tahun dasar 1988 n = Banyaknya produk tanaman yang dipakai dalam perhitungan. Sumber:.

Sumber:. http://www.fao.org/docrep/V9926E/v9926e05.htm#TopOfPage
ASPEK –ASPEK FISIKA PRODUKTIVITAS TANAH Sumber:.

Hubungan Sumberdaya Tanah dengan Sistem Pertanaman
ASPEK FISIK PRODUKTIVITAS TANAMAN Hubungan Sumberdaya Tanah dengan Sistem Pertanaman Pandangan tradisional tentang pengaruh tanah ialah bahwa “tanah” menyediakan “peluang” atau “kendala” bagi tipe-tipe sistem-pertanaman yang dapat diimplementasikan dan produktivitasnya. A more responsible view is that 'the soil' combines various properties which interrelate and are directly influenced by the procedures of cropping. Sumber:

ASPEK FISIK PRODUKTIVITAS TANAMAN
Pengelolaan Efek pd Tanah Agregat tanah hancur, membentuk kerak permukaan Penyingkapan muka tanah Ketersediaan air tanah berkurang. Kemungkinan genangan meningkat dan anaerobiosis Beban kendaraan Pemadatan tanah, pori tanah berkurang Penghancuran pori tanah Pemadatan: kekuatan tanah meningkat Dampak thd produktivitas tanaman Olah Tanah Kehilangan bahan organik Kehilangan hara Hara tidak seimbang Kehilangan hara anorganik Siklus Hara lambat: Waktu lebih lama untuk melepaskan kembali hara yg diikat tanaman sebelumnya menjadi tersedia bagi tanaman sekarang Kelimpahan dan jumlah Organisme tnh dekomposer berkurang Agrokimia Organisme tnh yg berasosiasi dnegan akar tanaman berkurang: Fiksasi N, Fasilitator P Sumber:

ASPEK FISIK PRODUKTIVITAS TANAMAN PORI TANAH & KARAKTERISTIK AIR
Tanah tersusun atas tiga bagian: bahan mineral, bahan organik dan rongga (disebut pori tanah). Peranan relatif dari bagian-bagian ini beragam dengan tipe-tipe tanah , tetapi biasanya pori menempati separuh dari volume tanah yang teksturnya medium. At optimum water content for plant growth, approximately half the pore space is filled with water and half with air. The proportions of water and air can change rapidly depending on weather, evapotranspiration and other factors. Sumber:

Dimensi (ukuran, bentuk dan tatanan) dan banyaknya ruang pori sangat penting dalam menentukan lengas-tanah dan struktur-tanah. Porositas merupakan volume rongga tanah (ruang pori). Pori ini dinyatakan dalam hubungannya dengan keseluryuhan volume tanah. Kapasitas menyimpan air suatu tanah tergantung pada porositasnya, dan distribusi ukuran porinya. Pori-halus menahan air dnegan tegangan lebih besar daripada pori besar. The moisture (or water) potential is the amount of energy required to remove water from a soil; field capacity is the water-holding capacity after a free-draining soil has been allowed to drain. The suction corresponding to this state has variously been defined as 0.33, 0.1 and 0.05 bar and so the convention used should always be checked. Wilting point, beyond which plants cannot exert sufficient suction to remove water from a soil, is generally considered to correspond to a suction of 15 bar. Sumber:

Kelompok ukuran-pori tanah dan fungsinya
Diameter Pori tanah (mm) Fungsi Equivalent particle atau Ukuran Agregat1 Sebab-sebab biologis (if not due to natural particle arrangement) Equivalent soil water2 tension (kPa) >0.5 Aeration and water transmission >1.6 (mostly gravel size, some coarse sand size) ants, worms <0.6 Water transmission (infiltration, permeability) (mostly coarse sand size, some fine sand size) roots Water storage (mostly silt and fine sand size, some clay size) lateral roots, root hairs < Residual (bound) water, unavailable to plants < (mostly clay size) fungal hyphae and bacteria >600 1 Equivalent particle size = 3.2 x pore size (assuming spherical, uniform size particles). 2 Based on equation: Pore diameter (mm) = 0.30/soil water tension (kPa). Sumber:.

Tititk Layu (gravimetric) % Air tersedia per meter Tanah
Nilai-nilai WHC dari berbagai kelas tekstur tanah (diadopsi dari Salter & Williams 1967) Kelas Tekstur Tanah Kapasitas Lapang (10 kPa) (gravimetric) % Tititk Layu (gravimetric) % Air tersedia per meter Tanah Coarse sand 8 4 80 Sand 14 150 Loamy sand 18 7 160 Sandy loam 26 9 180 Loam 30 13 Silty loam 34 16 200 Sandy clay loam 15 Clay loam Silty clay loam 43 20 190 Sandy clay 29 19 140 Clay 42 25 Sumber:

1 Strongly structured polyhedral subsoils, e.g. Krasnozem.
Nilai-nilai Konduktivitas Hidraulik jenus berdasarkan Tekstur dan derajat Struktur Tanah. 1 Strongly structured polyhedral subsoils, e.g. Krasnozem. TEKSTUR TANAH Structure Infiltration Permeability (mm/h) Sand Apedal Very rapid >120 can be measured >250 Sandy loam Weakly pedal >120 Rapid 60-120 Loam Peds evident Mod. rapid 20-60 Clay loam Moderate 5-20 Slow 2.5-5 Light clay Highly pedal Very slow <2.5 Medium to heavy clay Clay Sodic and saline 8.0 Sodic Highly sodic Extreme <1.0 Sumber:

Air tanah tersedia (ASW) adalah jumlah air yang tersedia untuk diserap oleh akar tanaman, yaitu air yang ditahan dnegan tegangan antara titik layu dna kapasitas lapang. ASW ini beragam dnegan tipe tanah dan biasanya berkorelasi dnegan kandungan liat dan struktur tanah. ASW juga beragam dnegan perlakuan tanah, karena ukuran dan distribusi pori dalam topsoil mencerminkan “terbukanya permukaan”, pembasahan-pengeringan musiman, dan pengelolaan tanah. Williams et al. (1983), studying the water content of 244 soil samples, found that the ASW of well-structured soils was one-third to twice as large as that in comparable (similarly-textured) poorly structured or degraded soils. Bearing in mind that ASW varies with natural weathering and management, Table 8 gives typical values of ASW for various soil texture classes. Sumber:

Konduktivitas hidraulik (K) tanah merupakan kemampuan tanah merembeskan gerakan air menuruni gradien tegangan. Nilai-nilai K yang tinggi berhubungan dnegan tanah-tanah yg strukturnya baik dan prositasnya kontinyu; kondisi ini memungkinkan laju infiltrasi air yang cepat dan drainage yng cepat. Earthworm channels, which can have populations of 500 m-2 in Mediterranean climates (Barley 1959), and continuous deep voids left by dead roots ( m-2) contribute greatly to hydraulic conductivity. Nilai K beragam dengan tipe tanah dan pengelolaannya (Table 9). Sumber:

Nilai-nilai K kurang dari 10 mm/h termasuk RENDAH dan senderung menyebabkan runoff setelah terjadi hujan atau problem irigasi, kalau intensitas hujan sekitar 10 mm/h. K values of 10 to 20 mm/h can give intermittent runoff (a downpour falls at about 50 mm/h) while values up to 120 mm/h are associated with occasional, increasingly rare runoff. Nilai-nilai K lebih dari 120 mm/h dapat membantu drainage reguler hingga groundwater, menyebabkan masalah potensial untuk tanah yang dipupuk dosis tinggi, pupuk kandang, limbah , herbicide dan pesticida. Sumber:

Both soil water content and saturated hydraulic conductivity generally relate to the number and continuity of pores, particularly the larger macro-pores. It is, however, difficult to measure these soil attributes and they are highly location-specific, so that variability is great and they sometimes have little interpretive value. Moran et al. (1988), however, in a study of a soil in a wet-and-dry environment, show that a soil treated with minimum tillage had more pores, identified directly by image analysis, and higher hydraulic conductivity, measured in the field, than did a similar soil traditionally cultivated. Gambar berikut menunjukkan dampak pengelolaan terhadap karakteristik pori tanah dan air tanah. Sumber:

Penampang vertikal tanah : Penampang vertikal tanah diambil dari perlakuan “direct drill (DD)” (a) dan tanah yg diolah konvensional (b) di lokasi yang sama. Nilai konduktivitas hidrauliknya berturut-turut adalah 42.5 dan 5.0 mm/h (Moran et al. 1988) Sumber:

PASIR: Butir lepas, terasa kasar dan cukup besar ukurannya untuk dapat diloihat secara individual butirannya; pasir kasar mempunyai ukuran partikel mm dan pasir halus mm. Silt: imparts a smooth, soapy or silky and only slightly sticky feeling, silt grains cannot be individually detected; their particle sizes range from 0.05 to mm. Clay: gives a sticky feel to the soil. Clay particles are less than mm diameter. These solid fractions contribute to the consistence and strength of the soil, and their packing determines bulk density. Bobot isi merupakan ukuran pemadatan atau pemampatan tiga komponen tanah. BI tanah dipengaruhi oleh komponen-komponen tanah, nilai-nilai BI yang menghambat penetrasi akar berkisar mulai dari BI = 1.4 g cm3 pada tanah-tanah liat hingga BI = 1.8 g cm3 pada atanah-tanah berpasir. Sumber:

Soil strength is the resistance of soil to shearing or structural failure. This reflects the friction which is built up between the soil and an implement, and depends on the density, and the roughness and shape of the soil particles. The shear strength of an individual clod decreases with wetting but, more importantly, the strength of the bulk soil increases with increasing moisture to about the lower plastic limit (known to field operators as the 'sticky point'), at which each particle is surrounded by a film of water which acts as a lubricant. Kekuatan tanah menurun drastis mulai dari suatu titik tertentu hingga batas atas-plastisitas, dimana tanah menjadi viscous. Perbedaan kandungan lengas-tanah antara batas atas plastis dan batas bawahnya disebut INDEKS PLASTISITAS, yg mencerminkan “daya-olah” suatu tanah. Besarnya nilai indeks plastisitas tanah mengisyaratkan perlunya banyak energi untuk mengolah tanah. Sumber:

STRUKTUR Tanah dan Pertumbuhan Tanaman Sifat fisik tanah mempengaruhi pertumbuhan akar dan batang secara langsung dan tidak langsung, misalnya melalui drainage yg buruk menyebabkan pori tanah dipenuhi air dan tanaman menderita akibat anaerobiosis. Root growth has been described under various soil physical conditions, but relationships have only rarely been established between features such as crop yield, root growth and soil pore size distribution or conductivity, a more aggregate measure. Sumber:

Akar dapat tumbuh memanjang ke arah bawah dengan kecepatan 8 cm/d, misalnya, kedelai yang tumbuh pada tanah lempung-debu dalam suatu rhizotron (Kaspar et al. 1978). Deep-rootedness and maximum rooting depth reflect soil properties (for example, roots will not grow through pores that they cannot deform to a larger diameter than the root). Kedalaman maksimum perakaran tanaman beragam dengan spesies tanaman dan tipe tanah. Sumber:

Akar tanaman gandum mampu menembus lapisan tanah sedalam 0.8 m pada tanah-tanah yg teksturnya berat (halus) dan mampu menembus hingga kedalaman 1.2 m pada tanah pasir berlempung (Rickert et al. 1987); tetapi biasanya ditemukan suatu varietas tanaman mempunyai kedalaman akar yg konsisten pada tipe-tipe tanah yang serupa dalam tahun tanam tertentu (Hamblin and Hamblin 1985) atau dalam suatu tipe tanah tertentu selama beberapa tahun. (Pearson et al. 1991). Angus et al. (1983) found that rice and six dryland crops (mung bean, cowpea, soybean, groundnut, maize and sorghum) extracted different amounts of stored soil water (ranging from 100 mm for rice to 250 mm for groundnut) and that extraction was, in part, related to rooting depth. Sumber:

The spread of roots with age can be related to the growth (increase in weight) of the whole plant, and to accumulated temperature or growing day-degrees (GDD); indeed, there is some evidence that temperature influences the direction of newly-appeared roots as well as the rate of appearance and extent of growth (Tardieu and Pellerin 1991). Clearly, however, there are factors other than plant size, temperature and soil which influence root proliferation. Otherwise the plants sown at three different times of year in the same soil would align their root growth along a single growth-GDD relationship. Faktor-faktor lain, seperti panjang hari, mungkin sangat penting, biasanya digunakan untuk menjelaskan hubungan antara pertumbuhan tanaman dan struktur tanah. Sumber:

Persebaran akar gandum dengan umur, dan efek pengolahan tanah terhadap pertumbuhan akar (Pearson et al. 1991) Sumber:

Pengolahan tanah dapat mempengaruhi panjang akar, meskipung efeknya baru muncul dalam tiga tahun. Perbedaan porositas tanah dapat diukur pada dua perlakuan pengolahan tanah : Pada tahun pertama ternyata pertumbuhan akar dan infiltrasi air (K sekitar 5 mm/h) sama besarnya pada kondisi olah tanah minimum dan pengolahan konvensional. By the third year, when differences were measured between roots, infiltration rates were 84 mm/h in minimum tillage and 0.2 mm/h under conventional tillage. Despite the differences in root growth there were no substantial differences in grain yield, reflecting the overall constraint of climate in the semi-arid environment. Sumber:

Values of air-filled porosity (%) and bulk density (g cm3) which are critical and which limit root growth for various soils (Source: Pierce et al. 1983) 1 "Critical" is defined as causing <20% reduction in root growth; "limiting" is about the value at which root growth ceases. Texture class Non-limiting Critical1 Limiting Air-filled porosity Fine loamy 20 10 5 Coarse silty Fine silty Clay: 35-45 15 >45 Bulk density Sandy 1.60 1.69 1.85 Coarse loamy 1.50 1.63 1.80 1.46 1.67 1.78 1.43 1.79 1.34 1.54 1.65 Claye: 35-45% 1.40 1.49 1.58 45% 1.30 1.39 1.47 Sumber:.

Peningkatan kerapatan tanah atau kekuatan tanah dapat menghambat penetrasi akar, sehingga membatasi volume tanah yang dapat dieksploitasi oleh tanaman dan air tersedia. Biasanya sulit mengkuantifikasikan hubungan antara sifat tanah ini dnegan pertumbuhan tanaman. In the cases of bulk density and strength, particularly, a gross measure of either for an undisturbed mass of soil can give only a remote indication of what a root encounters. A determination of gross bulk density does not assess whether a root is growing within a pore (in which case it may deform surrounding soil before its radial environment reaches the density or strength of the gross soil) or if it is growing within the soil material, in which case it has already exerted a radial force equivalent to that measured for the gross soil. Sumber:

Efek bobot isi tanah dan kekuatan tanah terhadap proses perkecambahan dan pertumbuhan panjang batang juga dipelajari. Batang (Shoot) mampu memanfaatkan pori makro tanah dengan tidak dibatasi oleh kondisi tanah secara keseluruhan. Nilai-nilai aktual lokal yg menghambat pemanjangan batang kecambah (shoot) tampaknya sangat kecil, misalnya, 0.76 kPa (Addae and Pearson 1992). Nilai-nilai ini berasal dari kajian pada kondisi yg terkendali, bebeda dnegan kondisi aktual di lapangan. The relative ranking of genotypes is, however, the same when under near-critical stress as when growing with virtually no mechanical stress. Genotypes suited to stressful situations may be selected, therefore, by screening at a single soil strength (Addae and Pearson 1992). Sumber:

Hubungan antara kekuatan tanah dengan panjang akar relatif tanaman jagung (Kang and Ghuman 1991)
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TABLE 11. Grain and stover yield (t/ha) of maize and seasonal water runoff and soil loss under maize grown with and without alley cropping, with two tree legumes, and tillage in Nigeria (Source: Kang and Ghuman 1991) . 1 Seasonal rainfall (March-July 1988) = mm. Treatment Maize Runoff1 (mm [% of rainfall]) Soil loss (t/ha) grain stover Without alley cropping Tilled control 2.3 3.1 66.0 (9.4) 6.18 No-tillage 2.4 3.2 5.6 (0.8) 0.43 Alley-cropped 2 m Gliricidia 4.6 4.8 (0.7) 0.57 4 m Gliricidia 2.8 4.2 23.1 (3.3) 1.44 2 m Leucaena 3.4 4.9 2.6 (0.4) 9.17 4 m Leucaena 3.9 10.7 (1.5) 0.82 Sumber:

Tanaman dapat mempengaruhi kualitas tanah melalui ground-cover, kedalaman perakaran, dan sifat-sifat tanaman lainnya. The crop attributes that most influence soil physical properties are speed of establishment and development of foliage cover. Rapid establishment and growth minimizes topsoil structural decline and soil erosion by wind and water. Thereafter, deep-rooting directly affects soil structure, particularly if deep-rooted crops, such as safflower, are grown in rotation as a 'biological plough' to create macropores and these are minimally disturbed before the next crop is sown. Sumber:

ASPEK FISIK PRODUKTIVITAS TANAMAN Contributing characteristic
TABLE 12. Desirable crop attributes that sustain soil productivity Attribute Contributing characteristic Rapid establishment (Relatively) large seed for establishment and seedling vigour; abundant seed for propagation Groundcover to reduce soil exposure, suppress weeds Early branching; perhaps rhizomes or stolons; horizontal leaves (high canopy-extraction coefficient) Low requirements for nutrients · Colonization by associative bacteria (e.g., Brachyrhizobiun), micorrhizae (e.g., Glomus) and free-living organisms (e.g., Azospirillum) · Low P, K, etc. requirement per unit dry matter, e.g., high "phosphate efficiency" Efficient water use Short growth duration (to utilize residual moisture after crop); high water use efficiency Deep rooting to reduce water table (salinity) and recover nutrients at depth and increase macropores Vertical root distribution; roots penetrate high impedence soils Useful products High leaf/stem ratio; edible seeds; easily digestible; no nutritional compounds in material for livestock; leaf retention on stems for cut and carrying to livestock Non-host for diseases and pests of main crop (to break disease cycle) or decoy (to attract diseases from concurrent crops) Botanically unrelated to main food crop(s) Suppress other species Allelopathy (leachates, exudates which suppress or kill other plant species); also physical attributes (as above) Sumber:.

Indikator Lapangan problematik Fisika-tanah Indikator lapangan yang lazim bagi kondisi fisika tanah yang buruk adalah: Patchiness or absence of vegetation. This can be an obvious sign of degraded structure or other factors. When structural, it may reflect surface structure degradation (see previous sections) or non-wetting characteristics which give rise to poor infiltration, or subsoil impermeability. Vegetasi bergulma. Cyperaceae atau Juncaceae dapat mencerminkan jeleknya struktur tanah, karena mereka tumbuh subur kalau air tergenang di permukaan tanah, menunjukkan jeleknya laju infiltrasi atau adanya lapisan bawah yang kedap air. Sumber:

Indikator Lapangan problematik Fisika-tanah Indikator lapangan yang lazim bagi kondisi fisika tanah yang buruk adalah: 3. Erosi permukaan dan erosi alur. Erosive runoff may be symptomatic of poor surface structure. The turbidity of water in ponds and lakes after rain may be a good indicator of erosion. 4. Kerak tanah di permukaan. 5. Permukaan tanah yang mengeras. Infiltrasi yang jelek dan genangan air. This may be indicated by puddles following rain in an area where one would expect rapid infiltration, or by wetting to only a shallow depth (as seen when dug with a spade). Sumber:

Indikator lapangan yang lazim bagi kondisi fisika tanah yang buruk adalah: 7. Warna tanah permukaan pucat dan tidak ada bahan organik. The surface of degraded soils may be brittle and pale, lacking organic matter and having lost clay either through eluviation (differential movement downwards) or by water or wind erosion. Berbongkah-bongkah (Cloddiness). This may be apparent if after a single cultivation, large, tough clods are formed requiring further cultivation to form a reasonable seedbed. Sumber:

Indikator lapangan yang lazim bagi kondisi fisika tanah yang buruk adalah: 9. Peetumbhuhan akar terhambat. This can be seen by digging with a narrow-faced spade and washing the roots free of soil. The root mass can be restricted to the upper soil or be constricted in particular places such as a less pervious layer, above and below which the roots may proliferate. Sumber:

Tanaman dan Hara dalam tanah
TABLE 16. Examples of farmer concepts/statements concerning aspects of sustainable crop production (Source: Fujisaka and Garrity 1991) Tanaman dan Hara dalam tanah Ubikayu dapat mengasamkan tanah. Ubikayu “menguras” hara dari tanah. Padi lebih toleran tanah-tanah masam dibandingkan Jagung. Rice is more vigourous on an area previously planted in tomato. Intercropping bagus kalau ketersediaan haranya cukup Sumber:

Pengurasan Hara Tanah:
Contoh Konsep/Pendapat Petani tentang aspek-aspek Produksi Tanaman Berkelanjutan (Fujisaka and Garrity 1991) Pengurasan Hara Tanah: Kesuburan tanah telah digunakan oleh tanaman. Tanah menjadi lemah. Fertility is spotty. Soils are overtrained. Tanah-tanah menjadi semakin lebih tua. Poor, but not used up, in the sense of the hardest part within a log. Sumber:

Lahan bero (kosong) - Fallows:
Contoh Konsep/Pendapat Petani tentang aspek-aspek Produksi Tanaman Berkelanjutan (Fujisaka and Garrity 1991) Lahan bero (kosong) - Fallows: Biomasa gulma yg terdekomposisi membantu memperkaya tanah. Lahan istirahat sehingga tanah dapat menyimpan sejumlah hara. Kaya karena beristirahat. Fertility is added and the soil is made cool. The soil is slightly enriched if left a short time. Sumber:

TABLE 16. Examples of farmer concepts/statements concerning aspects of sustainable crop production (Source: Fujisaka and Garrity 1991) Gulma - Weeds Padi dirugikan oleh akar-akar cogon (I. cylindrical). Tanah menjadi jelek kalau cogon dominan. D. longiflora and cogon consume soil nutrients and destroy soil quality. Kemasmaan tanah meningkat kalau cogon dominan. Gula kurus pada tanah-tanah tidak subur. R. cochinchinensis rapidly produces seed; thus, easily soars in population; if not weeded, it exceeds the height of rice or corn. Fertility is added and the soil is made cool" (re. Calapogonium spp.). Tanah menjadi baik kalau ada gulmua/rumput mempunyai bintil akar. Sumber:

TABLE 16. Examples of farmer concepts/statements concerning aspects of sustainable crop production (Source: Fujisaka and Garrity 1991) Erosi Tanah: Tanah terkikis dan terangkut ke tempat lain. Hara terangkut. Tumbuhan tererosi bersama dnegan tanahnya. Soil was drawn down and fertility was washed out. The land was shaven and eroded after trees were removed. Pupuk terkumpul (di bagian bawah petakan) karena terbawa air hujan. Sumber:

Pisang dan Kelapa lebih baik karena mereka mampu menahan tanah.
Tabel 16. Examples of farmer concepts/statements concerning aspects of sustainable crop production (Source: Fujisaka and Garrity 1991) Kontrol Erosion : Pisang dan Kelapa lebih baik karena mereka mampu menahan tanah. Pengolahan menurut kontur mengurangi kehilangan erosi. Jalur-jalur rumput dapat mengurangi efek erosi Trees planted above and below fields can decrease erosion effects. Banana planted above and below fields can decrease erosion effects. Sumber:

Pengelolaan: Pencegahan degradasi sifat fisika tanah
Aspek-aspek penting dalam memelihara atau ameliorasi sifat fisika tanah Pengelolaan: Pencegahan degradasi sifat fisika tanah Pilihan Pola Pertanaman: Rotations + sequential cropping Mixed cropping Relay cropping Alley cropping, parkland + agroforestry Sumber:

Aspek-aspek penting dalam memelihara atau ameliorasi sifat fisika tanah Pengelolaan: Pencegahan degradasi sifat fisika tanah Budidaya Tanaman : Olah Tanah + pengelolaan residu Waktu Tanam Seed quality and soil organism symbioses Pupuk anorganik Pengelolaan Bahan Organik Cultivar: ground cover, complementarity with other crops Manajemen gulma+hama secara hayati. Sumber:

Aspek-aspek penting dalam memelihara atau ameliorasi sifat fisika tanah Pengelolaan: Pencegahan degradasi sifat fisika tanah Inter-crop ley and fallow : Cover crop Pasture ley Maintenance of surface litter in absence of living vegetation Sumber:

Pencegahan degradasi sifat fisika tanah
Aspek-aspek penting dalam memelihara atau ameliorasi sifat fisika tanah Pengelolaan: Pencegahan degradasi sifat fisika tanah Mulsa : Mulsa hidup in situ Tumbuhan pupuk hijau Residu / seresah In situ Residu dari tempat lain Limbah ternak, kompos Limbah industri Penutup anorganik, mis. Kerikil Sumber:

Aspek-aspek penting dalam memelihara atau ameliorasi sifat fisika tanah Pengelolaan: Pencegahan degradasi sifat fisika tanah Amelioration to control damage : Pengelolaan erosi oleh air : Pengolahan tanah menurut garis kontur Saluran air bertingkat Guludan Saluran air berumput Ponds . Sumber:

Aspek-aspek penting dalam memelihara atau ameliorasi sifat fisika tanah Pengelolaan: Pencegahan degradasi sifat fisika tanah Ameliorasi untuk Mengendalikan Kerusakan Pengelolaan erosi oleh angin : Wind-breaks + interplanting dengan pohon Penanaman kembali dnegan Semak + pohon Penutupan muka tanah Pematang / tanggul Sumber:

TABeL 19. Aspek-aspek yg dipertimbangkan dalam ameliorasi sifat fisika tanah Pengelolaan: Pencegahan degradasi sifat fisika tanah Ameliorasi untuk Mengendalikan Kerusakan Pengelolaan Permukaan Tanah Menutupi dengan residu, limbah dari tempat lain, dll. Inter-cropping dan mulsa Pemadatan : Pengolahan tanah secara dalam, subsoiling Menanam tumbuhan yang perakarannya dalam Sumber:

ASPEK – ASPEK BIOLOGIS DAN KIMIA PRODUKTIVITAS TANAH Sumber:.

ASPEK BIOLOGIS DAN KIMIA PRODUKTIVITAS TANAH
BIOLOGI TANAH & LINGKUNGAN MIKRO Bahan organik, organisme mikro dan makro (mis. fungal hyphae dan invertebrates), detritus dari fungi dan binatang, bacteria, dan eksudat biologis, semuanya membantu menstabilkan struktur tanah. The role of each part of the biomass differs according to its size. Broadly, large aggregates greater than 250 m m diameter (macro-aggregates), are stabilized by their inherent physical structure , wetting and drying cycles, and organic matter. Mikro-agregat (< 250 mm) distabilkan oleh bentuk-bentuk hidup atau mati dari akar, fungi, invertebrata dan mikroba. Sumber:.

FIGURE 22 - Model of aggregate organization with major binding agents indicated (Source: Tisdall and Oades 1982) - Major binding agent Tanah Pori Sumber:.

Model organisasi agregat tanah dengan bahan perekatnya (Tisdall and Oades 1982) – Akar dan Hifa (keduanya bahan organik hidup) Akar Hifa Agregat tanah Sumber:.

Paket-paket partikel liat
Model organisasi agregat tanah dengan bahan perekatnya (Tisdall and Oades 1982) – Plant and fungal debris encrusted with inorganics (bahan organik persisten) Hifa Bakteri Paket-paket partikel liat Sumber:.

Model organisasi agregat tanah dengan bahan perekatnya (Tisdall and Oades 1982) – Residu mikroba dan fungi encrusted with inorganics (bahan organik persisten) Limbah Mikroba (material humik) Partikel Liat Sumber:.

Model organisasi agregat tanah dengan bahan perekatnya (Tisdall and Oades 1982) – Bahan amorf alumino-silikat, oksida-oksida dan polimer organik yg diserap pada permukaan liat dan ikatan elektrostatika, flokulasi (bahan anorganik permanen) Lempengan Liat Cement = Perekat Sumber:.

Populasi organisme tanah dari semua ukuran berhubungan secara fungsional melalui peranannya dalam degradasi bahan organik tanah. BOT ini meluputi bahan tumbuhan hidup dan mati, serta biomasa organisme lainnya hidup dan mati. Gambar berikut menyajikan jaring-jaring makanan (food web ) dalam tanah. This shows that animals such as nematodes and some fungi feed directly on live plants while other fungi and bacteria feed predominantly on litter. Sumber:.

Representation of detrital food web in shortgrass prairie. Fungal-feeding mites are separated into two groups (I and II) to distinguish the slow-growing cryptostigmatids from faster-growing taxa. Flows omitted from the figure for the sake of clarity include transfers from every organism to the substrate pools (death) and transfers from every animal to the substrate pools (defaecation) and to inorganic N (ammonification). Source: Doran (1987) Sumber:.

Earthworms and other large invertebrates create, and inhabit, burrows and pores, and are very mobile. The most notable of these are termites, which are divided into three groups according to the structure of their nests: those that build mounds (a) above ground, (b) on the soil surface, and (c) below ground. Small arthropods, microfauna and fungi live mostly in larger voids and in association with roots. Sumber:.

Foster (1988) reviewed the location of the various types of soil-dwelling organisms and found that fungi, which constitute about 80% of the biomass in many soils, tend to be restricted to the rhizosphere of roots, to larger pores between aggregates and to the surface of aggregates. Bacteria, by contrast, are found on roots in the rhizosphere, in small colonies in the larger micropores, within aggregates and on and within cell debris. For more information on location refer to Foster (1988). Smiles (1988) describes the physics of the micro-environment of small soil organisms. Sumber:.

BAHAN ORGANIK Tumbuhan dan hewan menyediakan bahan organik bagi tanah. Bahan organik tanah dapat dibedakan berdasarkan struktur kimiawinya, misalnya substansi humik kaya lignin yang sukar lapuk. The standing crop of litter in semi-arid grasslands is usually more than 3 t/ha and in temperate dry steppe may exceed 11 t/ha (e.g., Klemmedson 1989). There has been much debate about the relative contents of organic matter in tropical and temperate soils. Within those wet-and-dry climates that have hot summers assisting rapid decomposition, there is no evidence of inherently lower levels of organic matter in the tropics than in comparable temperate regions (Juo and Payne 1993). Sumber:.

EFEK BAHAN ORGANIK TERHADAP KESUBURAN TANAH (Young 1989)
Efek-efek Primer Konsekwensi Efek Fisika Binding of particles, root action leading to improved structural stability, balance between fine, medium and large pores Improved root penetration, erosion resistance and moisture properties; water-holding capacity, permeability, aeration Efek Kimia Nutrient source, balanced supply, not subject to leaching, with slow, partly controllable, release Including better response to fertilizers, non-acidifying source of N, mineralization of P in available forms Complexing and enhanced availability of micronutrients Increased cation exchange Better retention of fertilizer nutrients Improved availability of P through blocking of fixation sites Efek Biologis Provision of a favourable environment for N fixation Enhanced faunal activity Sumber:.

Kowal and Kassam (1978) ; Juo and Payne (1993) mengkaji peranan bahan organik di tanah-tanah tropika. Ternyata BOT mempunyai berbagai efek yang saling bertalian dengan kesuburan tanah. In particular it should be noted that both chemical and physical effects are of relatively great importance in the soils of the semi-arid tropics because these generally have low cation exchange capacity (effective CEC values less than 14 meq/100 g clay). Sumber:.

Kepentingan relatif seresah tanaman (crop residue) dan pupuk kandang sebagai inputs bahan organik, beragam di antara sistem-sistem pertanaman dan beragam secara spatial di salam suatu sistem pertanaman. The figure illustrates the flow of litter, manure and by-products (such as dung cake for fuel) in Indian villages practising approximately one-third single cropping and two-thirds double cropping. Sebagian besar biomasa bagian-tanaman di atas tanah dimakan oleh ternak, tetapi sejumlah yg hampir sama biomasa bawah tanah menjadi cadangan BOT. Sumber:.

Energy flow through the agro-ecosystems. Values are means from five villages = 1 SE (× 106 KJ/yr/ha cultivated land solar radiation = 6.5 x 1010 kJ/yr/ha (Source: Singh and Singh 1992) Sumber:.

ASPEK BIOLOGIS & KIMIA PRODUKTIVITAS TANAH
Pola aliran biomasa pupuk kandang dan sisa panen tanaman di lahan pertanian sangat beragam sesuai dengan praktek budidaya pertanian di daerah iklim basah dan kering. Biasanya semua biomasa akar ( misal, 40% dari total pertumbuhan tanaman) dan 10-30% dari biomasa tajuk tanaman di-daur-ulang dalam sistem pertanaman semusim. Where alley cropping and agroforestry are practised, values are more variable, but possible inputs could be very significant where the trees, from which the litter is taken, are grown away from the annual crops. Sumber:.

Kalau dua-pertiga daun-daun pohon legume dipanen setiap tahun, nilai biomasa seresah ini sangat besar dan kualitasnya lebih baik dibanding dengan jerami sisa panen tanaman semusim lain; biomasa legum ini sebagai pupuk hijau di-daur-ulang di lahan. Tree root material is not available for decomposition in the crop field unless it is spatially overlapping (e.g. as an intercrop), in which case the trees will compete with the crop for soil nutrients, water, light and space. Sumber:.

Produksi biomasa dedaunandari Pohon Multiguna (Young 1989)
Country Land use Tree t/ha/year Malaysia Plantation Acacia mangium 3.06 Philippines Albizia falcataria 0.18 Costa Rica Hedgerow intercropping Calliandra calothyrsus 2.76 Gmelina arborea 0.14 Indonesia (Java) L. leucocephala, A. falcataria, Dalbergia latifolia, Acacia auriculiformis Cordia alliodora 2.69 Plantation crop C. alliodora + cacao, 6.46 combination Erythrina poeppigiana, 4.27 E. poeppigiana + cacao 8.18 Nigeria Cajanus cajan 4.10 Gliricidia sepium 2.30 L. leucocephala 2.47 Tephrosia Candida 3.07 India Sumber:.

Laju dekomposisi biomasa seresah daun tergantung pd kondisi lingkungannya, terutama suhu dan lengas tanah. Kedua kondisi lingkungan tanah ini mempengaruhi penghancuran fisik seresah dan menentukan populasi & aktivitas hewan tanah serta fungi tanah yang “makan” bahan organik tersebut. Decomposition also varies with plant type and age of litter, being slower for heavily lignified material. The specific properties of litter from different species, and the generally exponential form of litter decay (the rate of decomposition slowing with time) lead to values that suggest half-lives of litter ranging from 1 to about 10 years. Sumber:.

Beberapa faktor yg mempengaruhi kecepatan dekomposisi BOT dan siklus hara adalah spesies tanaman, suhu dan lengas tanah, serta faktor pengelolaan tanaman. Ada empat cara untuk mengelola residu tanaman: Stubble mulch in which residues are left standing; Surface mulch, where above-ground residues are cut and left on the top of the soil after harvest; Incorporation by ploughing; and Cut-and-carry, in which surface residue is removed and (if not used for livestock or thatching, etc.) returned as a surface mulch about planting time for the subsequent crop; this is usually combined with ploughing of below-ground residues. Sumber:.

Konstante dekomposisi, k, untuk biomasa jenis legum tropis
Konstante dekomposisi, k, untuk biomasa jenis legum tropis. Nilai-nilai ini dihitung dnegan persamaan exponential untuk dekomposisi BO dengan memakai data dalam pustaka ( Juo and Payne 1993) Species Location Mean annual rainfall Mean annual temperature °C k/year Gliricidia sepium Ibadan, Nigeria 1250 23-31 8.48 Flemingia congesta 3.66 Cassia siamea 2.17 Lonchocarpus cyanescems 8.87 Inga vera El Verde, Puerto Rico 4000 22 1.65 Inga sp. And Erythrina (mixed) Caracas, Venezuela 1200 20 3.01 Erythrina sp. (mixed with non-legumes) 3.81 Inga edulis Yurimaguas, Peru 2200 26 0.91 Cajanus cajan 1.45 Erythrina sp. 3.72 Sumber:.

ORGANISME TANAH YG BERASOSIASI DNEGAN TANAMAN
Bacteria dan Nitrogen Cropping in dryland regions needs nitrogen to be economically successful (e.g., Keating et al. 1991). Two sources of nitrogen are from organic matter (Chapter 2, section Soil pores and water characteristics) and from nitrogen-fixing bacteria associated with plant roots. Bradyrhizobium and Rhizobium species infect plant roots forming galls or nodules, and fix nitrogen from the soil atmosphere directly to the plants. Locally-adapted, heat-tolerant strains survive from crop to crop in wet-and-dry climates and, whether established by natural colonization or by inoculation of the crop seed at sowing, they subsequently fix variable quantities of nitrogen. Kalau infeksi bakteri dapat efektif, bacteria biasanya dapat memfiksasi sekitar % dari total nitrogen yg digunakan oleh tanaman, proporsi ini lebih rendah kalau ada aplikasi pupuk N anorganik. Sumber:.

Efek N mineral tanah dan pupuk N terhadap produktivitas N tanaman dan proporsi (P) serta jumlah N-tanaman yg berasal dari fiksasi N2 ( Peoples and Craswell 1992) Species Location Level Total crop N2 fixed Soil mineral N (kg N/ha) Fertilizer N (kg N/ha) N (kg N/ha/crop) Proportion Amount (kg N/ha/crop) Groundnut India - 196 0.61 120 100 210 0.47 99 200 243 0.42 102 Chickpea Australia 10 (to 120 cm) 114 0.85 97 326 184 0.17 33 109 0.80 87 50 110 0.55 60 104 0.29 30 Soybean 70 (to 120 cm) 230 0.34 78 260 265 0.06 16 0* 63 18 148 0.26 28 0** 89 0.48 43 115 0.24 Sumber:.

ORGANISME TANAH YG BERASOSIASI DG TANAMAN
The extent of the effectiveness of infection of legume crops in the wet-and-dry tropics needs to be surveyed. Temperate research indicates that nitrogen fixed by bacteria ranges from 20 to 120 kg N/ha in a growing season for annual crops (Table 24). In the semi-arid tropics, amounts of nitrogen fixed per hectare range from none, where nodulation is ineffective, to 16 kg N in soybean naturally colonized by rhizobia, to 84 kg N when inoculated. Fiksasi Nitrogen pada kedelai dan kacang-tanah sebesar kg N/ha/musim tanam dilaporkan di Senegal (Gigou et al. 1985). Bakteri fiksasi Nitrogen berasosiasi dnegan pohon legume dapat memfiksasi sejumlah nitrogen seperti kedalai dan kacangtanah. Sumber:.

N fixation (kg N/ha/year)
Fiksasi Nitrogen oleh pohon dan belukar. Values are per growing season or per year unless the number of months is given in brackets (Young, 1989 ; Peoples and Craswell 1992) Species N fixation (kg N/ha/year) Acacia albida 20 Acacia mearnsii 200 Allocasuarina littoralis 220(?) Casuarina equisetifolia 60-110 Coffee + Inga spp. 35 Coriaria arborea 190 Erythrina poeppigiana 60 Gliricidia septum 13 Inga jinicuil 35-40 50 Leucaena leucocephala Leucaena leucocephala (in hedgerow intercropping) 75-120 (6) Sumber:.

Fungi, Algae dan Hara ORGANISME TANAH YG BERASOSIASI DG TANAMAN
Berbagai jenis fungi membantu penyerapan hara oleh akar tanaman, terutama phosphorus. Banyak jenis fungi hidup berasosiasi dengan akar tanaman. One group, vesicular arbuscular micorrhizal fungi (VAM), form both vesicles and arbuscules (knot-like structure) on the surface and within the root. They also colonize soil animals including earthworms and woodlice. Sumber:.

Mikroba ini banyak dijumpai dalam topsoil hingga kedalaman 10 cm (Habte 1989). Mereka ini membantu penyerapan hara, terutama fosfor dari tanah yang miskin fosfor. Mereka ini juga menyediakan proteksi bagi tanaman inangnya, keberadaannya dapat menurunkan kolonisasi oleh patogen. Ellis et al. (1985) also found that wheat plants inoculated with VAM were more drought-tolerant than plants without VAM. Importantly, comparisons of conventional cropping systems using inorganic fertilizers and herbicides with organic systems not using herbicides have found much higher levels of infection of crop roots by these beneficial fungi in the organic system (Ryan et al. 1994). Pengelolaan organisme tanah yg bersifat asosiatif dan menguntungkan menjadi bagian penting dari sistem pertanaman yg lestari. Sumber:.

Conventional tillage maize
Frequency (%) fungi VAM dalam macro-invertebrata tanah yang diambil dari ekosistem alam dan pertanian di Ohio (data are combined from 1986 and 1987 samplings) (Source: Rabatin and Stinner 1989) Taxa Ekosistem Conventional tillage maize No-tillage maize Pasture Old field Lumbricidae (earthworms) 25.0 83.3 50.0 75.0 Isopoda (woodlice) 100.0 35.7 64.7 36.8 Carabidae (ground beetles) 2.1 19.8 14.5 12.8 Sumber:.

GULMA, HAMA & PENYAKIT TANAMAN Gulma, hama dan penyakit semuanya bersaing dnegan tanaman atau secara langsung mereduksi vigour tanaman. Banyak hama dan penyakit bersifat “soil-borne”. Weed life-cycles depend on replenishment of the soil seed bank and survival of the seeds against natural decay, predation by soil animals and depletion by human management, particularly cultivations. Ecological weed control thus aims to minimize recruitment of new seed into the soil as a long-term strategy as well as trying to reduce artificially the size of the weed seed bank in the soil. Sumber:.

KETERSEDIAAN HARA DALAM TANAH
HARA ANORGANIK Hara anorganik dalam tanah dapat berbentuk ion dan mineral misal. Oksida-oksida, silikat dan fosfat; keduanya dijerap pada permukaan partikel liat dan bahan organik , dan ada dalam larutan tanah. Sebagian besar dari hara, terutama nitrogen, ditemukan dalam bahan organik tanah, sehingga BOT dan organisme tanah sangat penting bagi per-hara-an tanah. Clay particles, because of their crystalline structures, carry an inherent electrical charge. This results in attractive forces (mainly van der Waals forces) and repulsive forces (electrostatic forces) which give clay species their particular characteristics. The inherent surface charge also causes a layer of associated ions to align next to the solid particles forming a so-called diffuse double layer because it consists of a relatively inexchangeable layer (the Stem layer) closest to the surface of the particle and an outer, readily exchangeable layer, of varying thickness, called the diffuse layer. Sposito (1984) explains this more fully. Sumber:.

Penjerapan (Adsorption) merupakan akumulasi neto materi pada ruang antara fase padatan dan fase cairan. Ion-ion yang mudah ditukar dijerap dg kekuatan “lemah” pd permukaan koloid tanah dan mudah dapat digantikan dnegan jalan pencucian menggunakan larutan elektrolit. KTK tanah merupakan jumlah mole ion yg dijerap dan dapat digantikan dari suatu unit massa tanah; ion-ion seperti ini lazim disebut “ion mudah ditukar”. Sposito (1984) notes that 'Much controversy exists over the surface chemical significance of ion exchange capacities'. The maximum surface charge measurement indicates a soil's potential to adsorb ions while its actual capacity, which is more relevant agriculturally, has a lesser value. Table 28 gives representative cation exchange capacities (CECs) for selected soil orders. It is notable that though the CEC of each order ranges widely, the predominant soils in wet-and-dry climates have low CECs. Sumber:.

Nilai-nilai KTK lapisan tanah permukaan (molC/kg) (: Sposito 1984) ORDO TANAH KTK Alfisols 0.1 2 ± 0.08 Aridisols 0.16 ± 0.05 Entisols 0.13±0.06 Histosols 1.4±0.3 Inceptisols 0.19±0.17 Mollisols 0.22±0.10 Oxisols 0.05±0.03 Spodosols 0.11 ±0.05 Ultisols 0.06 ±0.06 Vertisols 0.37 ± 0.08 Sumber:.

Proporsi kation tukar dalam KTK beragam dengan pH tanah; proporsi basa-tukar yg mudah tersedia menurun dari sekitar 1 pada pH 8 dan 0.5 pada pH 6 menjadi sekitar 0.2 pada pH 4.5. Pada kondisi pH kurang dari 6 terjadi peningkatan ion-ion aluminium yang dapat bersifat toksik. The electrical conductivity and CEC of a soil are related to its clay content (e.g., Rhoades 1990a). Similarly, because of the electrical charge of the clay particles, a high but variable percentage of the soil organic matter is bound to them. It may be as high as 90% ; and there are the two postulated main ways that organic matter is bonded to clay. These are weak anion exchange and strongly-held ligand exchange which is a form of chemical bonding. Sumber:.

Proporsi C-organik dalam tanah yang berbentuk Kompleks Liat-Organik.
1 Defined as the material sinking when the soil was ultrasonically dispersed in an organic liquid of density 2 g/cm3. Percent organic carbon in soil Percent soil carbon in clay-organic complex1 Podzol 1.5 18 Solonized brown soil 77 Grey clay soil 1.1 91 Terra rossa 2.8 82 Groundwater rendzina 5.4 69 Black earth 1.8 Krasnozem 4.9 90 Red brown earth 2.5 66 Sumber:.

Liat dan bahan organik tanah mempunyai muatan listrik, dan keduanya mempunyai sumbangan besar dalam menentukan kemampuan tanah menahan hara-tersedia dan stabilitas struktur tanah. Pieri (1992) mengusulkan bahwa stabilitas struktur tanah (untuk tanah-tanah di Afrika yg ditelitinya) dapat dideskripsikan dengan nilai kritis S lebih besar dari 9, dimana S adalah rasio bahan organik dengan (liat plus debu) , dinyatakan dalam persentase. Sumber:.

Diagram jembatan anionik : Pertukaran Anion.
R adalah Koloid humik poli-anionik humic colloid. Sumber:.

Diagram jembatan anion: Pertukaran ligand.
R adalah koloid humik poli-anionik. Sumber:.

Tingkat kritis BOT untuk mempertahankan stabilitas fisik struktur tanah (Pieri 1992) Sumber:.

Akar tanaman menyerap hara anorganik dari larutan tanah (kecuali legumes, yang mampu memfiksasi nitrogen langsung dari udara tanah). Unsur hara dapat tersedia bagi tanaman kalau ia berbentuk ion bebas dan berada dalam zone perakaran. Ion-ion hara dalam tanah bergerak memasuki zone akar melalui pergerakan air tanah, dan ion hara memasuki tanaman melalui evapotranspiration. Diffusion along concentration gradients is important for less-mobile ions such as phosphorus, particularly where soil solution concentrations are weak and root densities are high (i.e., the transport path is short). Sposito (1984) and others give calculated values for the diffusivity of nutrients. Diffusion times range from 1 day for an ion to move 3 mm (which is comparable with the time it would take to move by convection in the mass flow of water) for nitrate to about 200 days for potassium, magnesium and molybdenum, and to thousands of days for other nutrients. Sumber:.

pH rendah mempengaruhi akar tanaman secara langsung karena efek konsentrasi H+ thd integritas membran sel akar dan kapasitas pertukarannya. Kemasaman jug mempengaruhi akar secra tidak langsung melalui dua cara. Ia mengubah ketersediaan ion dalam larutan tanah (membuat spesies Al tersedia yg toksik bagi tanaman plants). Ia juga mempengaruhi mineralisasi melalui proton yg bersaing dengan cations untuk mendapatkan ligand yg terlarut dan gugus fungsional pd permukaan yg bermuatan. Soil pH also affects micro-organisms, and thus the speed of transformations, for example, those between nitrate and ammonium. Poor plant growth on acid soils may thus be caused directly by hydrogen ions, by toxicities of aluminium or manganese, or through deficiencies of calcium, magnesium, potassium, phosphorus, nitrogen or trace elements. Sumber:.

Chase et al. (1989) describe these relationships for sandy Sahelian soils. Variation in pH across distances of 15 m can be as much as pH 4.5 to 7.5, with associated decreases in aluminium and hydrogen ions, and increases in crop productivity. Nilai kritis pH yang mempengaruhi pertumbuhan tanaman ternyata beragam dnegan jenis tanaman, cultivar dan tipe tanahnya. Tingkat kritis ini dapat sebesar pH untuk jenis tanaman yg tidak toleran Al , tetapi jenis tanaman lainnya yang toleran mempunyai nilai kritis pH Sumber:.

INDIKATOR PROBLEMATIK BIOLOGIS DAN HARA
Bahan organik tanah berhubungan dengan partikel (mineral) tanah secara kimiawi dan secara fungsional. BOT berhubungan erat dengan berbagai problematik biologis dan ketersediaan hara dalam tanah. Rates of loss of organic matter independent of erosion tend to be slow, but important as they are cumulative. Pada kondisi lingkungan lahan-kering di Afrika Barat, laju kehilangan BOT dapat mencapai 2-4% per tahun. Sumber:.

TABLE 31. Annual rate of organic matter loss measured in the field in the savannah area (Source: Pieri 1992) Place and source Dominant rotation Clay + silt (%) (0-20 cm) Annual rate of loss Notes k (%) No. of years Burkina Faso Ploughed Sorghum monocropping 12 1.4 10 No fertilizer 1.9 Low rate manure 2.6 High rate manure 2.2 m + crop residues Cotton-cereal 19 6.3 15 Much erosion Cameroun 17 3.2 5 2.9 Fertilizer 2.5 Fertilizer + kraal Côte d'Ivoire - 2.3 3 0.4 Improved fallow Sumber:.

Larson dan Pierce (1991) mengusulkan bahwa seperangkat data yg dikumpulkan secara analitik sangat penting untuk memantau kelestarian tanah. They include two measures of organic matter among the ten attributes that they consider essential (Table 32). Their concept of requiring agreed minimum data sets is consistent with the approach to assessing sustainability . Kalau seperangkat data tersebut telah diperoleh (Larson and Pierce 1991), setiap atribut tanah ditentukan dengan waktu referensi tertentu (T0) dan perubahan kondisi tanah dapat diukur selama periode waktu tertentu (T1), misalnya 1 – 10 tahun. Sumber:.

TABLE 32. Soil attributes and standard methodologies for their measurement to be included as part of a minimum data set (MDS) for monitoring soil quality (Source: Larson and Pierce 1991) Soil attribute Methodology Total organic carbon Dry or wet combustion Labile organic carbon Digestion with KCI Nutrient availability Analytical soil test pH Glass electrode-calomel electrode pH meter Electrolytic conductivity Conductivity meter Texture Pipette or hydrometer method Plant-available water capacity Determined in field best or from water desorption curve Structure Bulk density from intact soil cores field measured permeability of Ksat Strength Bulk density or penetration resistance Maximum rooting depth Crop specific - depth of common roots or standard Sumber:.

Pengukuran C-organik tanah secara langsung dianggap tidak-efektif biaya dan tidak informatif. It is more likely that surrogate measures are adequate and, if sufficiently simple and cheap, have some likelihood of being used. Pieri (1992) suggests that a bleached (possibly brittle) soil surface and plant deficiency symptoms are useful surrogates for loss of organic matter, low CEC and soil nutrient imbalances. Kehilangan BOT biasanya dibarengi dengan degradasi struktur tanah, indikator-indikator seperti turbiditas air permukaan (mis. Air sungai) dianggap sangat berguna. Sumber:.

Hara Mineral dan Problematik Kesuburan Tanah (Source: Pieri 1992) General problems Signs of simple problems Where they occur Probable causes Limitation of nutrient supply to crops · Nutrient imbalance Deficiency in organic matter Bleaching and destruction of soil surface Senegal, Niger, Burkina Faso, Mali Insufficient return of crop residues Accelerated mineralization of dry matter Too little fertilizer Defisit N (S) N (S) deficiency in cereals, legumes and cotton Throughout area Too little N (S) applied in fertilizers or manures. High C/N ratio Very little N fixation Leaching of nitrate K-Ca-Mg deficit K deficiency, Al toxicity Frequent K deficiency in cotton Al toxicity in groundnut and cotton (Senegal) Severe leaching of Ca, Mg, K. Fertilizers low in Ca, Mg, K. · Low buffer capacity Progressive drop in CEC Loss of fine mineral and organic soil particles Senegal, Mali, Cote d'Ivoire, Burkina Faso, Niger, Chad Poor erosion control Rapid mineralization Acidification Senegal, N Cote d'Ivoire, Burkina Faso, Chad NO3/Ca + Mg leaching Fertilizers too low in Ca, Mg Too little or no liming Tanah-tanah Marjinal Nutrient deficiencies Senegal, N Togo, S Mali, Burkina Faso Land shortage Poor cultivation Sumber:.

Indikator defisiensi hara meliputi : warna (mis. Kemerahan unt defisiensi kalium); pucat (gejala umum, tetapi merupakan gejala khusus defisiensi N); daun-daun kecil dan tanaman kerdil. Other symptoms, such as leaf curling and accelerated dropping of older leaves, may also be helpful but might equally indicate water deficits. There are several publications with photographs of nutrient deficiencies; these, however, might require further tailoring to specific combinations of crops and soils. Sumber:.

Gejala efek kemasaman tanah dicirikan oleh tanaman kerdil, muka tanah bersih vegetasi, dan jenis-jenis gulma yg toleran asam tumbuh lebih baik. Salinitas juga dicerminkan oleh perubahan vegetasi seperti pohon mati tanpa alasan yg jelas atau meningkatnya populasi herba yg toleran garam. Other symptoms of salinity include: waterlogged or bare soil; livestock congregating and licking the soil surface for salt; visible salt crystals; the smell of salt; and clear catchment water because salt settles sediment. Sumber:.

Pengelolaan unt Memelihara Biologi dan Hara Tanah The aim of management should be to create balanced organic matter and mineral budgets. It should ensure that, over several years (a complete crop rotation), soil organic matter is not depleted and that nutrients added equal or exceed those removed by cropping or lost in various ways. When managing organic matter farmers should recognize that the effects of animal and human manure, sewage sludge and plant residues last longer than those of green manure crops. Manfaat pupuk hijau biasanya berlangsung selama satu atau dua musim, karena bahan organik ini dimasukkan ke tanah sebelum dewasa (tua) dan berlignin. Efek jangka panjang bahan organik terhadap organisme tanah juga ada. Sumber:.

Pemeliharaan: Pencegahan Degradasi
Aspek-aspek yg dipertimbangkan dalam memelihara dan ameliorasi biologi tanah dan hara tanah Pemeliharaan: Pencegahan Degradasi 1. Pemilihan Tanaman · Preference for rotations and intercropping with several species, as for Table 19 · Inclusion of legume in rotation 2. Praktek Budidaya Tanaman · Aplikasi pupuk anorganik untuk menjaga neraca hara yg netral · Konservasi seresah tanaman · Aplikasi kotoran manusia dan hewan · Incorporation of organic wastes from industry and cities · Olah tanah minimum · Pengelolaan hayati hama dan gulma · Mengurangi laju pengasaman melalui pemilihan jenis tanaman, pengelolaan seresah dan pupuk. 3. Pengelolaan Air · Water harvesting · Minimization of salinity, if a problem is likely, through seasonal leaching and other practices Sumber:.

Ameliorasi untuk mengontrok kerusakan :
INDIKATOR PROBLEMATIK BIOLOGIS DAN HARA Aspek-aspek yg dipertimbangkan dalam memelihara dan ameliorasi biologi tanah dan hara tanah Ameliorasi untuk mengontrok kerusakan : 1. Ketidak-seimbangan dan defisiensi hara · Berdasarkan gejala visual, aolikasi pupuk anorganik · Mengubah pola tanam untuk mengurangi efek kemasaman 2. Degradasi permukaan tanah melalui kehilangan BOT, erosi tanah oleh air dan angin : Aplikasi bahan organik berupa limbah organik, mulsa, tanaman penutup tanah dll. Sumber:.

Pola dan Pergiliran Tanaman mempengaruhi ketersediaan hara tanah.
INDIKATOR PROBLEMATIK BIOLOGIS DAN HARA Pola dan Pergiliran Tanaman mempengaruhi ketersediaan hara tanah. Diversitas pertanaman meningkatkan jumlah dan ragam organisme tanah dan mengurangi hama dan penyakit. Soil acidification and salination are extreme cases of nutrient imbalance and, unlike other deficiencies, cannot be corrected simply by adding mineral fertilizers. Teknik pengelolaan tanah unt mengurangi asidifikasi: Mengurangi produksi proton dengan jalan meminimumkan pencucian nitrat (problem khusus di daerah iklim musimaan basah-kering); Menghindari penggunaan pupuk ammonium dan mengurangi akumulasi bahan organik; Mengapur tanah. Sumber:.

EVALUASI PRODUKTIVITAS TANAH-TANAMAN
Pengelolaan bahan organik sisa panen untuk mengembalikan kesuburan tanah

EVALUASI PRODUKTIVITAS TANAH – TANAMAN

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EVALUASI PRODUKTIVITAS TANAH – TANAMAN

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