Nutrition Management In Oil Seed Crops: Deepak Fertilisers & Petrochemical Corporation Ltd.

Balanced fertilization of NPK proved beneficial in all the oilseed crops both under rainfed and irrigated conditions. Application of P to raya, in K-deficient soil, is more effective when combined with N and K. As a general guideline, N and P₂O₅are recommended in the 2:1 ratio except in legume oilseeds. Under Ca-deficient conditions, application of Ca improves the uptake of B and K in groundnut besides Ca.

Doses of a particular nutrient in balanced proportion is also equally important considering cost of mineral fertilizer and the antagonistic or synergistic effect of different nutrients. Several studies have shown the interaction effects of NxP, NxS, KxS, CaxS, and SxZn are synergistic whereas PxS (high level), SxMo and KxMg are antagonistic in influencing yield, nutrient uptake of different oilseed crops.

Application of more than required N and P often has deleterious effect of NxP interaction on seed yield of sunflower. The decrease in seed yield with higher N and P can be due to large proportion of unfilled seeds in the flower heads. Excessive N prolongs growth period and delays maturity. At lower levels of N, Indian mustard responded to S significantly up to 10 Kg/ha, however, with the increased supply of N from 60 to 90 kg N/ha, the S need of the crop was significantly raised to 30 kg S/ha.

An application of 40 kg P₂O₅ and 45 kg S as basal gave maximum pod yield, oil yield and protein content of groundnut kernel.

Organics: Various organic sources like FYM, poultry manure, green manure, crop residues and compost can supply adequate amounts of nutrient, including micronutrients to crops. In groundnut application of FYM @ 7.5 t/ha increases the pod yield by 60% over 25:50:25 NPK kg/ha. Application of 5 t/ha poultry manure to groundnut of P-deficient soils increases the pod yield compared to FYM alone.

Crop wastes and residues are renewable and readily available resources. Recycling of crop residues is a viable strategy to meet at least a part of the nutrient requirement of oilseed crops.

Although the role of organic manures in improving nutrient use efficiency is well established by now, the actual consumption continues to be very low. As most of the recommendation includes FYM / compost and green manure as organic nutrient sources, their limited availability deprives the farmer from adopting recommended packages. What is actually required is to develop and popularize location specific technological recommendations in non-traditional sources such as on-farm and off-farm wastes and by-products of agro-industries. Experimental evidences suggest a fairly higher crop response to combination of these materials. Further, to reduce the use of mineral fertilizer, to make a balanced proportion of nutrients supply and to prevent depletion of soil nutrients there is a good possibility for utilizing nutrients potential of biological and industrial wastes in an integrated manner.

Biological sources: Biofertilisers are a potential source of supply of low cost nutrients. Nitrogen requirement of the crop through fertilizer source was reduced when it was inoculated with the bio fertilizers. In groundnut, yield improvement of 5.5-17.1% was obtained due to the use of Rhizobium cultures. The new rhizobial strains, viz. IGR 6 and IGR 40 were found to be tolerant to thiram; hence, seed treatment with fungicide and application of Rhizobium can be combined. Azospirillum seeds treatment in sesame and Azotobactor in toria and sunflower reduces the N requirement of the crops by half. Combined use of super phosphate @ 13.2 kg P/ha and Pseudomonas striata could save 13.2 kg P/ha. Rock Phosphate @ 13.2 kg P/ha with Pseudomonas striata could also be a more economic and alternative source of phosphorus. Use of Pseudomonas striata with both the sources of phosphorus (super phosphate and rock phosphate) proved more effective P-solubilizer than Aspergillus awamori in medium black soils. Use of phosphate solubilising bacteria in conjunction with neem cake, castor cake, or FYM gave higher yields of sesame. Also 26.4% increase in soybean and 20.9% increase in groundnut yields were reported with inoculation of mycorhiza. Glomerella fasciculatum.

Conjunctive use of mineral fertilizer with organic and biological sources of plant nutrients commonly referred as integrated nutrient supply system, is an established agro-technique for sustaining yield levels, enhancing nutrient use efficiency and restoring soil physical, chemical and biological health.

The fertilizer consumption ratio throughout the country in all the production systems is highly imbalanced with higher even undesirably excess dose of N at the cost of other major nutrients particularly K. Soil test based fertilizer application is the only way of balanced nutrition. In fact, scientific basis of fertilizer application should be on soil test value. This concept is important particularly for micronutrients. Application of micronutrients without soil test may become toxic because its direct effect is much less than macronutrient. Also fertilizer application without soil test increases the cost of cultivation. Soil test based balanced fertilizer application has resulted in 18-26% increase in crop yield. Integrated use of fertilizers and organic sources as per STCR approach holds promise for sustaining the oilseed production at higher level. However, it necessitates efforts on three points

i) strengthening of Government run soil testing laboratories with modern equipments and trained human resources.

ii) building confidence among the farmers towards these soil testing services, which largely lacks at present, and

iii) creating mass awareness on emerging plant nutrient deficiencies and long term benefits of soil fertility maintenance and balanced fertilizer use.

Mineral fertilizer: If a cereal or non legume crop succeeds Kharif groundnut, 20-25 kg N/ha can be reduced; and P application is not required if groundnut has already been supplied with P. Leguminous crops in general can more effectively utilize less soluble Ca-phosphate. Groundnut being legume crop has relatively higher nutrient absorption efficiency from soil P.

In case of soybean-wheat system, as the total P requirement of soybean is much higher (80 kg P₂O₅) than groundnut (20-40 kg) it can only partially meet its P requirement from the residual P left in the soil from adequately fertilized wheat crop.

Higher S-use efficiency in cropping systems can only be obtained when S is applied to a higher responsive crop in crop sequences and when better land management is practiced which conserves S for the succeeding crop.

Organic manures: Cropping systems based nutrients management is one of the key approaches of integrated nutrient management. The low level of utilization of nutrients supplied through fertilizers and manures calls for choosing appropriate combination or system of crops to effectively utilize the nutrients for long-term sustainability.

Application of right kind of plant nutrient at proper time with appropriate method is one of the strategies to reduce various losses of the nutrient that, in turn, increases the nutrient-use efficiency.

In sesame, it is highly desirable to apply 50% N at sowing and 50% N at 30 DAS. Similarly, split application in hybrid sunflower (50% N as basal and 25% N each at 45 and 70 days after sowing) is advantageous. Practice of split application of N is more beneficial to use opportunistically the rainfall distribution pattern under rainfed conditions that helps to reduce the risk and cost, with concomitant increase in the N-use efficiency.

Since top dressings of N are commonly practiced, ammonium sulphate is an ideal fertilizer for correcting S deficiency in standing crops and providing an integrated N plus S supply. All phosphate fertilizers should be applied at the time of sowing. The efficiency of phosphate fertiliser depends on the source from which it is derived. Single super phosphate (SSP) is largely preferred for oilseed crops as it contains Ca (19.5%) and S (12.5%) besides few micronutrients. Given the predominance of ammonium sulphate and single super phosphate in the market place, they remain as important sources for N, P and S fertilization.

Calcium nutrition is groundnut is beneficial for the development of well filled pods and kernels and improved shelling percentage. The SSP and gypsum are superior to ammonium sulphate for groundnut as source of S and Ca. However, in acid soils, gypsum may not be as effective as CaCO₃ because of the latter's effect in eliminating exchangeable. A1 besides providing Ca. Similarly, in some calcareous soils like in medium black soils, the presence of high amount of lime could become a problem. The best method of applying gypsum is to band place the material near the pegging zone at the early flowering stage.

Application of Zn increases nodulation; chlorophyll content and pod yield of groundnut. In Zn deficient soils, application of zinc sulphate @ 10-50 kg or 0.02% foliar spray is suggested. Application of 10 kg Zn improved the seed. Boron appears to be the most essential micronutrient element for sunflower. Only small but adequate amount of B is required by different soilseeds. Sunflower yield can be increased to be extent of 30% by dusting Borax @ 2 kg/ha on capitulum only during ray floret opening stage.

Availability, mobility and uptake of plant nutrients are primarily dependent on soil moisture. In general, oilseed takes up more nutrients per metric tonne of grain than cereals for a given availability of water. Increased available soil moisture from 25-75% improves the mustard response to 60 kg N + 40 kg P₂O₅ / ha by 2.3 times.

At low level of P (15 kg/ha) application, adequate soil moisture has enhanced the P utilization by four folds in mustard. Adequate water supply enhances the mass and distribution of the root system. The roots that are actively growing are capable of taking up nutrients by exploiting a greater volume and depth of soil compared to other roots. In-situ soil moisture conservation practices like broad bed and furrow system, set row cultivation have been recommended for efficient utilization of the applied nutrients in groundnut crop.

Plant genotypes differ in their ability to respond and utilize nutrients. In calcareous soils where lime-induced iron chlorosis is a major problem causing yield reduction in groundnut, genotypes like Dh 8, PKVG 8, GG 2 identified as iron efficient genotypes should be grown to prevent any further yield loss.

Sulphur efficient genotypes showed more chlorophyll (both a and b) and carotene contents than the sulphur inefficient genotypes.

The quality decides the market price. Phosphorus application has been found to increase crude protein, oil content and iodine number of oil in groundnut and sunflower mainly due to the role of certain P containing enzymes in fatty acid synthesis in seeds. Sulphur plays an important role in improving the quality and marketability of produce. On an average the improvement in oil content in major oilseeds due to S application is 11.3% in groundnut. 9.6% in mustard, 9.2% in soybean, 6.0% in linseed and 3.8% in sunflower.