FERTILISER TECHNICAL

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Introduction

Food security, nutritional security, sustainability and profitability are the main focus of present and future agricultural development, With the current food production level of 203 million tonnes India has to step up foodgrain production by next decade to feed the burgeoning population. The production of 1mt/ha of cereal grain means removal of about 20 kg N/ha and about 4kg P/ha. With the possibility of horizontal expansion or putting more land under cultivation being remote, future augmentation in yield would have to be harnessed vertically through judicious management of all the input resources. In fact, nearly 50 per cent gain in foodgrain productivity seen in recent times has come through fertilizers alone.

Soil Fertility Status
Soils of India are generally poor in fertility as these are low in organic matter and have consistently been depleted of their finite nutrient resources due to continuos cultivation for many centuries. The low and declining soil fertility are the main causes of low productivity of most of the cultivated lands.

Nutrient Status of Indian soils and extent of deficiencies

Nutrient	Soil fertility status
Nitrogen	Low in 228 districts, medium in 118, high in 18 districts
Phosphoprus	Low in 170 districts, medium in 184, high in 17 districts
Potassium	Low in 47 districts, medium in 192, high in 17 districts
Sulphur	Deficiencies encountered in 100 districts
Magnesium	Kerala, other southern and northeastern states, very acid soils
Zinc	49% of 2,50,000 soil samples analysed found deficient
Iron	Important on upland calcareous soils
Boron	Deficient in parts of Bihar, Karnataka, west Bengal

The above table shows that N deficiency is universal and nearly 49, 20 and 47 per cent soils of India are deficient in P, K and Zn respectively. Sulphur deficiency is recorded in 125 districts. The Fe, Mn and B have also become most serious constraints in some agricultural production systems.

Constraints

Deterioration of soil organic stock: The total mass of organic carbon stored in the upper 30 cm soils in India is only 21 Pg(1Pg=10 15 gm). It is speculated that due to deforestation and other agricultural activities (human included), the carbon equilibrium has already been disturbed in many parts.
Low fertilizer use efficiency: It is estimated that the response in terms of Kg foodgrain per kg of nutrient declined from 15 in 1975-76 to 7.6 in 1988-89. In case of N use efficiency exceeds 40 per cent under lowland and 60 per cent under upland conditions. In case of P and micronutrints fertilizers, the efficiency hardly exceeds 20 and 2 per cent respectively.
Imbalance in NPK ratio: The fertilizer consumption in the country ranges from 1.3-299 kg N/ha, 0.5-89 kg p2o5/ha and 0.2-95 kg K2O/ha. There is deparity in consumption ratio of NPK (8.5:3.1:1 in 1998-99), which is more pronounced in the northern states (37.1:8.9:1) indicating highly imbalance use of fertilizers.
Disparity in fertilizer consumption: There are a lot of disparities in the fertilizer consumption pattern both between and within the eco-regions of the total 525 districts in India. Nineteen districts consume more than 200 kg/ha, 35 districts between 150-200 kg, 75 districts between 100-150 kg and 132 districts between 50-100 kg/ha. Further 84 districts account for 50 percent of the total consumption.

Demand for soil nutrients in future

Indian agriculture is operating on a net negative balance of plant nutrients at the rate of 8-10 mt/annum. This continuos nutrient imbalance can become staggering when we consider the future need of food production. For a production level of 300 mt foodgrain, India will need at least 45 mt of plant nutrients. Demand of mineral fertilizer would be 35 mt consisting of 5.6 – 8.8 mt P₂O₅, 2.3 to 4.7 mt K₂O and the rest of nitrogen. At least 10 mt of nutrients should come from organic manures, crop residues and bio-fertilizer. Besides, there will be considerable demand for micro and secondary nutrients.

Estimation of the removal of different micronutrients under varying cropping systems

Cropping system	Yield Mt/ha	Zn g/ha	Fe g/ha	Mn g/ha	Cu g/ha	B g/ha	Mo G/ha
Rice-Rice	4+4=8	320	1224	2200	144	120	16
Rice-Wheat	4+4=8	384	3108	2980	168	252	16
Maize-wheat	4+4=8	744	7296	1560	616	-	-
Soybean-Wheat	2.5+4=6.5	416	3362	488	710	-	-
P.Pea-Wheat	2+4=6	287	3456	493	148	-	-

Organic Resources

Rural and Urban Compost: The potential of rural and urban composts in India is estimated to be 800 and 16 mt respectively, out of which only 280 and 6.6 mt, were actually produced till last few years.

Crop Residue: About 400 mt of crop residues are produced in the country which have potential of supplying about 7.3 mt of NPK. According to an estimate, only about one-third of the residue potential is available for utilisation in agricultural production.

Legumes: Leguminous green manure can fix large quantity of atmospheric N₂which generally can accumulate about 100 kg N/ha in 50-55 days but can reach up to more than 200 kg N/ha.

Biofertiliser: Crop response to biofertiliser inoculation is highly variable, location specific, crop specefic and management specific. Inoculation of Rhizobium, Azatobacter and Azospirillum substitute, 19, 22 and 20 Kg N/ha respectively.

Future Strategies
In order to provide a sound and logical basis for successful implementation of balanced and Integrated Nutrient Management the following measures need to be taken up.

Greater awareness needs to be created among the farmers on farm resource generation and its proper recycling.
Soil testing laboratories should be strengthened and upgraded for soil and plant analysis for both macro and micronutrients.
Advantages of introduction of green legumes in the cropping systems should be promoted.
Use of Phospho-compost should be promoted to supplement phosphatic fertiliser to a great extent.
Nutrient export/drain through crop leaching, gaseous/volatisati0on, erosion etc. need to be evaluated.
Efforts should be made to enhance shelf life of bio fertilizers, to develop new strains through genetic engineering.
Research on incorporating N fixing ability in non-legumes need to be accelerated.
Government policies on promoting fertilizer use must ensure their sustained use through pricing policies on fertilzers and agricultural produce that make their use economically viable.

Note: All India company wise capacity / production of fertilizers, Country wise export and imports, State wise / District wise / Crop wise / Season wise consumption of fertilizers, and any other type of information regarding fertilizer production and consumption can be made available on request.

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