Improving the Efficiency of Rice Straw Composting by Addition of a Protein Hydrolysate As a Nitrogen Source

The aim of this study is to evaluate the suitability of a protein hydrolysate (PH) prepared from waste leather as a nitrogen source supplement during rice straw (RS) composting, with urea-amended treatment as a control. Changes in several primary physicochemical properties were similar between the two processes; both resulted in matured end-products within 65 days. However, the PH as a nitrogen source provided some remarkable benefits compared with urea-amended treatment; the PH supplement yielded a higher temperature increase rate (1.85 degrees C/h vs. 1.07 degrees C/h) at the start-up of RS composting process. The efficiency of volatile solid degradation was higher too (48.04% vs. 46.98%, mainly attributed to greater cellulose degradation). Application of the end-product of PH-amended treatment in a pot experiment yielded the highest Chinese cabbage biomass relative to the blank and chemical fertilizer treatments. These results prove the feasibility of RS composting using PH as a nitrogen source, evidenced by improved composting efficiency and enhanced quality of the end-product.