Long-term effect of nutrient management on soil biochemical properties in a vertisol under soybean-Wheat cropping sequence

Abstract

The present investigation was conducted during 2013–14, under an ongoing long-term fertilizer experiment (LTFE) with soybean-wheat cropping system, since 1972 at the Research Farm of Department of Soil Science and Agricultural Chemistry, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur, Madhya Pradesh, India, under the aegis of All India Coordinated Research Project on Long-term Fertilizer Experiments. The chemical and biological properties of soil under different nutrient combinations were studied in the 41-year old LTFE in a Vertisol. The experiment was conducted in a randomized block design comprising of eight treatments i.e. 50% NPK, 100% NPK, 150% NPK, 100% NP, 100% N, 100% NPK+ farmyard manure (FYM) @ 15 t ha−1 yr−1, 100% NPK-S and unfertilized-control, with four replications. Soil samples from all treatments were collected from 0–15 cm depth and biochemical properties were determined. Significant increase in soil organic carbon was recorded with 100% NPK + FYM @15 t ha−1. The availability of N, P, K, S, soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) were increased significantly with the integrated application of fertilizers and FYM over control and other fertilizer treatments. Further, the conjoint use of fertilizers and FYM was also significantly superior to other treatments in terms of activities of soil enzymes like dehydrogenase, acid phosphatase, alkaline phosphatase and βglucosidase. The correlation studies revealed significant positive relationship of available N, P, K and S, SMBC, SMBN, dehydrogenase activity, alkaline phosphatase activity, acid phosphatase activity and βglucosidase activity with total productivity of soybean and wheat crops.