Nitrogen mineralization kinetics in Typic camborthid soil amended with spent mushroom composts and farm yard manure

Abstract

A laboratory experiment was carried out in completely randomized design with three replications under controlled conditions (25±1 °C) as an incubation study for 12 weeks. Bulk surface soil samples (0–15 cm) of sandy loam (Typic camborthids) was air-dried, ground, passed through a 2mm sieve, and mixed homogeneously. The required amount of organic amendments viz. White button spent mushroom compost (WB-SMC), Dhingari spent mushroom compost (D-SMC), and farm yard manure (FYM) @ 0.75% on dry weight basis were added in 500 g soil. After thorough mixing the soil and organic amendments, triplicate samples of (20 g) for each treatment and twelve incubation periods were transferred to 125 ml wide mouth plastic bottles. A control treatment without any organic amendment was also run. The containers were incubated in BOD incubator for 12 weeks and moisture content at field capacity was maintained throughout the incubation period with double distilled water by weighing the containers on alternate days. On completion of each incubation period i.e. 1, 2, 3, 4, 5, 6, 7, 8, 10 and 12 weeks, triplicate samples of each treatment were removed from the incubator and extracted immediately with 2 M KCl solution for determination of mineral-N. The cumulative amounts of mineral N in control soil as well as organic amendments treated soil increased with increase in incubation period. Among organic amendments, WB-SMC accumulated higher amounts of mineral N in soil followed by FYM and D-SMC. The lower accumulation of mineral N under D-SMC treatment as compared to WB-SMC or FYM was presumably due to immobilization of native mineral N by increased soil micro-organism activity.