Physico-chemical, microbial and phytotoxicity evaluation of composts from sorghum, finger millet and soybean straws

P. S. Jagadabhi, S. P. Wani, M. Kaushal, M. Patil, A. K. Vemula, A. Rathore
2018 International Journal of Recycling of Organic Waste in Agriculture  
Purpose Composting is an environmentally sustainable alternative for bioconversion of agricultural residues into a nutrientrich product that can enhance soil fertility/microbial diversity and thereby improve agricultural productivity. The goal of the current study was to evaluate the decomposition pattern of the agro-residues and assess the maturity and phytotoxicity of the composts obtained using physico-chemical, microbial and statistical analyses. The study also attempted to determine a
more » ... hold germination index (GI) to serve as a maturity index for the composts by conducting seed germination assays with tomato, chickpea and soybean seeds. Methods Three agricultural residues/straws of Eleusine coracana (finger millet), Sorghum bicolor (sorghum) and Glycine max (soybean) were subjected to aerobic composting for a period of 60 days to study the impact of saw dust on the decomposition pattern and the ultimate compost quality/characteristics. Results The results showed efficient decomposition pattern of the agricultural residues characterized by high temperature profiles (up to 70 °C), high microbial activity, a sharp decrease in C/N ratio of the composting materials, i.e., from an initial 41-61 to final 10-17. Conclusions Statistical evaluation of seed germination assays showed that only the compost obtained from sorghum straw + saw dust was mature and free from any phytotoxicity as all the tested seeds showed higher and statistically significant GIs. It was difficult to attribute a single threshold GI value to indicate maturity of compost and could not further be applied to different types of composts as different seeds responded differently to the same compost.
doi:10.1007/s40093-018-0240-8 fatcat:vb6gfvexy5bm5ohrgydnumrk3e