Rainfed Agriculture needs special dispensation• Limitations of rainfed areas – Moisture – Soil fertility – infrastructure – Other income generating options• Lack of public policy support – Technology development – Marketing – subsidies
What we should think of ….• Integrated farming systems integrating livestock, trees etc• Building soil organic matter• Conserving moisture• Rainwater harvesting• Locally adopted crops and varieties• Contingence planning
Rainwater management Vermicomposting Combination of Planting on bundsMixed cropping practices
Soil productivity Management• Plants as nutrient mining systems• Soil is understood as strata to hold plants• Only available nutrients are measured• External nutrient application-no measure of utilisation• Soil-chemical, biological and physical properties• Biomass application is also seen as external nutrient application…so measures only the content
Major and micro nutrients Micro NutrientsSource Air Water Soil Soil Carbon Hydrogen Nitrogen Manganese Oxygen Phosphorus Molybdenum Nitrogen Potash Copper Calcium Boran Magnesium Zinc Sulfur Chlorine Iron
Essential Nutrients of Plants Element Chemical symbol Atomic Wt. Ionic forms absorbed by Approximate dry plants concentration Macronutrients Nitrogen N 14.01 NO3-, NH4+ 4.0 % Phosphorus P 30.98 PO43-, HPO42-, H2PO4- 0.5 % Potassium K 39.10 K+ 4.0 % Magnesium Mg 24.32 Mg2+ 0.5 % Sulfur S 32.07 SO42- 0.5 % Calcium Ca 40.08 Ca2+ 1.0 % Micronutrients Iron Fe 55.85 Fe2+, Fe3+ 200 ppm Manganese Mn 54.94 Mn2+ 200 ppm Zinc Zn 65.38 Zn2+ 30 ppm Copper Cu 63.54 Cu2+ 10 ppm Boron B 10.82 BO32-, B4O72- 60 ppm Molybdenum Mo 95.95 MoO42- 2 ppm Chlorine Cl 35.46 Cl- 3000 ppm Essential But Not Applied Carbon C 12.01 CO2 40 % Hydrogen H 1.01 H2O 6% Plant tissues also contain other elements16.00 Se, Co, Si, 2Rb,O F, I) which are not % Oxygen O (Na, O , H2 Sr, 40 needed forthe normal growth and development
Liebig principle Plant growth is influenced by a nutrient at lowest concentration as a denominator
Water ManagementModern agriculture: irrigation, drip,sprinklerSustainable Agriculture: focuses more onconserving soil moisture, increasing organicmatter, mulching, cover crops, croppingpatterns etc…
Rainwater conservation measures Conservation of the entire rain water in the field itselfComponents include Trench,Conservation furrows, Farm Pond,compost pit , tank silt application.Rs. 48,000 per acre - MGNREGS •3.19 lakh acres of 1.46 lakh SC/ST farmers 2009- 10 •10 lakh acres in 2010-11
Factors influencing soil fertility and moisture Rainwater Organic Matter Living beings Soil StructureSoil depth Minerals Soil depth Water flow Nutrient release Basic minerals Groundwater
Soil Organic matter The soil organic matter has declined from about 1.43 and 1.21 % in red and black soils in the 1950’s to about 0.80 to 0.86 percent respectively at present. Soil organic matter performs Hydrological, Biological and Nutrient related functions, which are both interrelated and distinct. The OM helps tide over dry spells and in reducing runoff. Soil moisture and organic matter is essential even for improving the efficiency of biofertilisers and chemical nutrients. For better decomposition Maintain C:N ratio in the range of 30-40:1 Application of water regularly to maintain around 60% moisture
Organic Matter is PossibleBiomass source Biomass per Year (kgs/ ac) RemarksGliricidia/ Cassia 3000 to 4000 30kgs/ plant – from 5th year of plantingSunhemp sown on bunds/ 350 @1.3 kgs/ sqm. 50% ofborders bund length of 280 mBiomass yielding trees` 450 @150 kgs/ tree, two loppingsWeeds 200 - 300Crop residues 500 - 1000Legume inter-crop 500TOTAL 4000 - 5000
Green manure (legumes) crops when integrated as intercrops, would add about 1.5 to 3 tons/ ha of fresh biomass in situ. Studies have shown that legume intercrops can add 0.30 to 2.4 tons of leaf litter per ha even in a drought year; with 4.1 to 35.6 kg N per ha.
Micro organismsDecomposition by microorganisms releasesNutrientsProtect plants from diseasesImproves soil structure Macro organisms •Incorporate organic matter in soil •Makes capillary pores in the soil to increase water infiltration and air circualtion
‘P’ for Plants• Applied water soluble ‘P’ is, on an average, used @ 12-9-6-3% from year of application• Considerable (70%) part of applied ‘P’ is locked in the soil first as tricalcium phosphate (TCP) and finally as apatite• in paddies, under heavy soils, considerable part of applied ‘P’ gets converted into apatite• P in TCP is unavailable but can be used by plants in association with Mycorrhizae and to some extent by Phosphobacteria
Factors limiting P availability and uptake• Amongst the nutrients, nitrogen is universally limiting and in most trials this aspect is given due attention.• But more often, the widespread Zinc deficiency is ignored and it could as well be a limiting factor in showing response to applied P• At lower levels or production, the native phosphorus itself may be adequate and thus no response to applied P• Some elements may become toxic (e.g. Boron). Subsoil salinity could be another factor• With temporary or transient water logging or wet regime, Fe 3+ iron may be reduced to Fe2+ leading to possible precipitation of phosphates• The organic acids released by the legumes (Pscidic acid from pigeonpea roots) would solubilise phosphates or chelate metal irons like Ca 2+, Fe2+ liberating part of the bound phosphorus. The VAM fungi may also accentuate the availability of phosphorus.• VAM and other fungal bodies associated with roots improve the availability of difficulty available phosphates• Method of application is important in enhancing fertiliser P use efficiency. Placement, in association with ammonical nitrogen is very effective.
Organic matter increases P availability in four ways. First, organic matter forms complexes with organic phosphate which increases phosphate uptake by plants. Second, organic anions can also displace sorbed phosphate. Third, humus coats aluminum and iron oxides, which reduces P sorption. Finally, organic matter is also a source of phosphorus through mineralization reactions.Flooding the soil reduces P-sorption by increasing the solubility of phosphates thatare bound to aluminum and iron oxides and amorphous minerals. Soil critical values for phosphorus for different groups of crops Level of P Crop group Critical level requirement of P (P2 O5) Low Pastures, grasses, 35 small grains, field corn, soybean, etc. Moderate Cotton, sweet corn, 60 tomato etc. High Potato, onion etc. 90
In natural forestsa fistful of soil contains600-800 bacteria3000 fungi which are miles longer10000 unicellular organisms20-30 nematodesLiving in soil, making soil fertile and avoiding diseasecausing organisms
Soil where chemical fertilisers are used Organically managed soils
How to increase soil organic matter Leaving crop residues in field Composting Using organic manure with and mulching with crop residues Green manure crops and Practicing good tillage Good cropping patterns
Crop Choices• Market demand• Soil and growing conditions
Crop duration Water requirement cropsOne season (< 4 Low Greengram,months blackgram, chickpea, kharif groundnut Medium Jowar, maize, rabi groundnut,More than one season More Cotton, chillies(6-8 months)Year or longer Very high Sugarcane, banana
Based on soil depth • Shallow roots (60 cm): ragi, sama, korra, onion, cauliflower, cabbage, potato • Medium deep roots (90 cm): groundnut, chillies, wheat, tobacco, castor • Deep roots (120 cm): maize, sugarcane, jowar, bajra, safflower, soybean, tomato, carrot, cucumber
Crop Management in Rain-fed areas• Low water consuming crops• Perennials on conservation furrows including green leaf manure plants.• 7 tiered crop canopy ( 36*36 model ) near farm pond.