Response surface method Box-Behnken design-based optimization of organic fertilizer enrichment using bat guano

Agricultural environmental pollution needs to be reduced in our future. The biggest obstacles to preventing this situation are that agricultural inputs such as synthetic fertilizers increase product yield and scattered agricultural areas. This study involves the optimization of the production process of an easy-to-apply organic fertilizer with high nutritional value by subjecting bat guano, one of the valuable organic fertilizers, to anaerobic digestion together with cattle manure. Response surface method Box-Behnken design, a statistical model, was used for process optimization. The process input parameters were temperature, cattle manure, and bat manure, and the response value was considered as 2% total nitrogen. As a result of the optimization for a total nitrogen value of 2%, the optimum mixture ratio was determined as cattle manure 77.0448%, bat manure 12%, and temperature 40 °C. Analysis results showed that the addition of bat manure increased the N, P, K, and humic and fulvic acid values in the fertilizer. The study revealed that strong organic fertilizers can be used to increase the value of cattle manure organically. It also offers very promising results based on reducing agricultural pollution and ensuring agricultural sustainability.