Effect of Long-Term Integrated Nutrient Management (INM) Practices on Soil Nutrients Availability and Enzymatic Activity under Acidic Inceptisol of North-Eastern Region of India

ABSTRACT

Soil acidity is one of the main limitations for optimal use of land resources for better crop production. And, long-term fertilization experiments found to be helpful in increasing the nutrient supply in these acidic soils. Keeping this in view, a field experiment on rice was carried out by applying biofertilizers and enriched compost in an acidic Inceptisol of Assam over 10 successive years (2006–15) to examine its effects on nutrient availability and soil enzymatic activity. This experiment had five treatments viz. absolute control (T₁), 100% recommended doses (RD) of inorganic NPK (T₂), 50% RD of inorganic NP + 100% K +biofertilizers (T₃), 50% RD of inorganic NP + 100% K +1 tonne enriched compost ha^?1 (T₄) and 25% RD of inorganic NP + 100% K +2 tonnes enriched compost ha^?1 (T₅) under randomized block design with four replications. After completing 10 years of experiment, it was observed that integrated use of enriched compost and biofertilizers with reduced doses of inorganic fertilizers enhanced the soil enzymatic activity as well as nutrient availability in rice grown in acidic clay loam soils of Assam. Application of biofertilizers and enriched compost had positive impact on plant accessible nitrogen, phosphorus and potassium in soil as compared to inorganic fertilizers. Also soil organic matter content increased considerably by these treatment. Integrated nutrient management practice in rice had also significantly enhanced the dehydrogenase, fluorescein diacetate and phospho-monoesterase activity in soil.