Effects of Adding Bacillus sp. on Crop Residue Composting and Enhancing Compost Quality

Abstract

Local farmers tend to burn crop residues to simplify soil preparation for the following season cultivation. Along with the environmental conservation policies that were implemented by the government, local farmers began to consider the adverse effects of crop residue burning. In this regard, efficient utilization of organic resources through composting of crop residues has been practiced. The objectives of this study were to find out the effects of adding Bacillus sp. on composting of crop residues and to observe the effects of Bacillus sp. added crop residues on plant growth. The number of Bacillus sp. colonies existing in crop residue and soil were determined by agar culture medium. Composting was carried out based on the number of Bacillus Bacterial colonies (cfu): 1.5×10¹⁴, 1.5×10¹⁶ or 1.5×10¹⁸ cfu. Carbon-to-nitrogen (C/N) ratio and number of Bacillus Bacteria were measured once a week. To observe the effects of Bacillus sp. added compost on plant growth, pots were prepared as control pots; crop residue pots; Bacillus sp. added crop residue pots; and burned crop residue pots. Komatsuna (Brassica rapa) were cultivated. Based on the experimental results, it was found that compost with higher number of Bacillus sp. have significant decrease of C/N ratio with time. Also, it was found that the mass of the crops in the pots added with Bacillus sp. (average 1.4 g) was larger than that control pots (0.5 g). Therefore, adding of Bacillus sp. can promote decomposition of crop residues and enhance the quality of compost.