Kinetics of nitrogen mineralization in sewage amended soil

Abstract

A laboratory experiment was carried out at, Jaunpur (25°18’ N, 83°03’ S) to study the kinetics of N mineralization in sewage amended soils. Four different agricultural fields viz., A, B, C and D which has been receiving sewage for irrigation since last five or more years were selected for study. The three replicate of each treatment were incubated at room temperature (25°C) for 7 weeks. The soils were brought to field capacity by addition of distilled water. The subsamples (10g) were withdrawn from each sample after every week interval and extracted immediately with 100 ml of 2 M KC1 solution and N was determined. The fitness of the model for mineralization study was tested by least square method and the mineralization rate constant (K) and half-life (t1/2) were calculated from fitted model. It was observed that, the highest mineralized N (121.20 mg/kg) was observed in soil receiving sewage continuously while lowest in N mineralized 112.80 mg/kg was observed in soil receiving less amount of sewage. Estimated mineralization rate content ‘K’ in four soils was 0.44, 0.38, 0.10 and 0.43 and correlation coefficient were 0.99, 0.98, 0.99 and 0.99, respectively. The study revealed that, nitrogen mineralization was increased with increasing period of incubation with rapid increase during 2–4 weeks of incubation. First order model of kinetics was best suited for nitrogen mineralization in sewage amended soil under study.