Integrated nutrient management in rice
THE CONCEPT of Integrated Nutrient Management (INM) takes into consideration the nutrient cycle involving soils, crops and live stock, nutrient deficiencies, organic recycling, conjunctive use of organic manures and mineral fertilisers and biological nitrogen fixing potential.
Fertiliser use should be increased by appropriate techniques such as split application of nutrients at important phonological stages of crop growth, incorporation of basal dose of fertilisers, use of coated and slow release fertilisers and combination of organic and inorganic fertilisers.
Use of indigenous sources such as press mud, granulated compost material and mixing urea with neem cake in ratio of 5:1 could result in higher nitrogen use efficiency. Long-term fertiliser experiments have revealed that the efficiency of P&K increased appreciably when both are applied in conjunction, suggesting their positive interactions.
Correction of imbalances
In strongly acidic or iron rich acidic soils with high amount of organic matter, rice often suffers badly from aluminium and iron toxicity and gives very poor yields.
Liming at 500 kg/ha and provision for drainage will correct the toxicities and increase yields.
In K - deficient soils. Rice often suffers from iron toxicity and hence application of K increases yields in such cases by increasing K and decreasing P concentration in plants.
Using organic manures
While nutrient deficiencies could be met largely through chemical fertilisers, desirable soil physical properties such as water holding capacity, congenial conditions for microbial activity and efficient use of applied fertilisers could be maintained by additional of organic manures.
The ease of handling, storage and application of chemical fertilisers coupled with their quick and dramatic results, results in neglecting the use of organics.
If current agricultural practices continue on the existing model, organics may disappear from the scene, and our soils in many areas would soon become deserts or unfit for food crop cultivation.
Chemical fertilisers are better utilised in the presence of organic manures. The availability of nutrients in organic manures is stimulated by increased microbial activity and complementary through chemical fertilisers.
The sustained use of organics in rice crop also increases higher uptake of all nutrients when used along with inorganic fertilisers. Application of 30-50 per cent of total nutrients in the form of organic manures would improve the soil physical properties, increase microbial activity, enhance the response per unit of nutrient added, facilitate slow release of nutrients, reduce nutrient losses and provide a long term build up of soil fertility.
B. Vijay Kumar
& M. Sreenivasulu
Sr. Scientist (Crop Production) and Scientist (TOT),
Angrau, DAATTC, Mahabubnagar
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