Microbial and physico-chemical analysis of composting process of wheat straw

Composting is a method of solid waste management to convert organic matter into agriculturally useful humus like substance to enhance nutritional and physical quality of soil. In an attempt to produce quality compost, studies were conducted for six months to investigate the physiological and biochemical changes during the composting of wheat straw. To monitor the composting process a consortium of bacterial isolates (Bacillus subtilis D3L/1, B. subtilis B1U/1 and Pseudomonas sp. RAT/5) (10(7) CFU/mL) was used. After 60 d of incubation, the wheat straw turned black, showed distinct physical changes and emitted odour. Periodical analysis of C/N ratio revealed that ratio of final product was 17:1. Other parameters like NO3- (1.5%) and NH4+ ion (0.3%) concentration along with pH (7.0 +/- 0.2), K+ (44%) and PO4-3 (15.46-33.18 mg/Kg) concentration were also recorded. Maximum activity of amylase together with protease and cellulase were recorded after 60 d of incubation and found to be 44.9-54, 62.28-193.02 and 29.1 U/g, respectively; whereas dehydrogenase activity reached its maximum (4168 U/g) at 30th d. Salmonella population did not appear throughout the study period. The load of fastidious organisms was 5.3-5.7 U log(10) CFU/g up to 30 d that disappeared thereafter, but the coliform population was predominating. Certain fungal strains were detected with potato dextrose agar medium. Physiological, biochemical and morphological character of the final product revealed that aerated static pilling is suitable for compositing of wheat straw.