Effect of Integrated Nutrient Management on Soil Quality Indicators and Soil Quality Indices in Hill and Mountainous Inceptisol Soils in Northern India under Maize (Zea mays) - Black gram (Vigna mungo) System

Abstract

A long term study was conducted in the rainfed Inceptisol soils at All India Coordinated Research Project (AICRPDA), Rakhdhiansar (J&K) from 1998 to 2005. The main objectives of the present study were to quantify the long-term effects of conjunctive nutrient management on soil quality parameters, to identify the key indicators of soil quality using data redundancy technique and to compute integrated soil quality Index (SQI) and relative soil quality Index (RSQI) as influenced by long term INM treatments in Hill and mountainous Inceptisol soils in Northern India under maize - black gram system. Six INM treatments were considered for the study viz., T1: Control; T2: 100% N (inorganic); T3: 50% N (inorganic); T4: 25 kg N (compost); T5: 15 kg N (compost) + 10 kg N (inorganic) and T6: 15 kg N (compost) + 20 kg N (inorganic). After eight years of study, results revealed that the soil organic carbon was significantly higher with the long term application of 25 kg N (compost) (5.20 g kg-1) and 15 kg N (compost) + 20 kg N (inorganic) (5.19 g kg-1). Among the macronutrients, available N and P were significantly influenced by the integrated nutrient management treatments while available K was not influenced much. Significantly highest available N content of 156.5 kg ha-1 was observed with the application of 25 kg N through compost and significantly highest available P of 36.7 kg ha-1 was recorded with the application of 15 kg N (compost) + 20 kg N (inorganic). Among the secondary nutrients, irrespective of their significant influence, the content of both exchangeable Ca and Mg, varied from 2.47 to 3.76 cmol kg-1 and 0.43 to 0.52 cmol kg-1 respectively. Available S, being significantly influenced by the nutrient management treatments was observed to be highest under application of 25 kg N through compost (22.7 kg ha-1). Among the micronutrients, available Zn and B were conspicuously influenced by the management treatments while Fe, Cu and Mn were not influenced. Among the biological parameters viz., DHA, microbial biomass carbon (MBC) as well as labile carbon were significantly influenced by the management treatments. Application of 15 kg N (compost) + 20 kg N (inorganic) recorded significantly highest DHA (2.79 μg TPF hr-1g-1) as well as labile carbon (355.0 μg g-1 of soil) while application of 25 kg N (compost) recorded significantly highest MBC of 162.0 μg g-1 of soil. Among the physical soil quality parameters, both bulk density as well as mean weight diameter were significantly influenced by the management treatments. Soil quality assessment studies indicated that available N, exchangeable Ca, available Zn, & B, MBC and bulk density were found to be the key indicators of soil quality under maize-black gram. Among all the treatments practiced under maize-black gram system, application of 25 kg N through compost had significantly highest RSQI of 0.97 which was at par with application of 15 kg N (compost) + 20 kg N (inorganic) (0.94) ( P=0.05). The order of performance of the treatments in terms of soil quality was : 25 kg N (compost) ( 0.97) >15 kg N (compost) + 10 kg N (inorganic) (0.87) > T 100% N (inorganic) (0.83) > 50% N (inorganic) (0.81) > Control ( 0.63).