EVALUASI PRODUKTIVITAS TANAH : ASPEK BIO-KIMIA

EVALUASI PRODUKTIVITAS TANAH : ASPEK BIO-KIMIA
Mk. Stela-smno.fpub.jun2014

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:.

ASPEK BIOLOGIS DAN KIMIA PRODUKTIVITAS TANAH
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:.

Sumber:. http://www.fao.org/docrep/V9926E/v9926e05.htm#TopOfPage
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:.

Sumber:. http://www.fao.org/docrep/V9926E/v9926e05.htm#TopOfPage
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:.

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