Manure applications combined with chemical fertilizer improves crop yield and soil functionality

The current farming system is highly reliant on synthetic fertilizers, which adversely affect soil quality, the environment, and crop production. Improving crop productivity on a sustainable basis is a challenging issue in the current agricultural system. To address this issue, we assumed that the combined use of manure and chemical fertilizers (CF) could improve rice grain yield and soil properties without the expense of the environment. Therefore, a two-year field experiment was conducted to explore optimal fertilizer management strategies using a combination of CF and organic fertilizer in the form of cattle manure (CM) or poultry manure (PM). Manure was added at two levels and soil microbial biomass production, enzyme activities, nutrient content, as well as grain yield of rice were measured. The study consisted of six treatments: no N fertilizer control (Neg-Con); 100% chemical fertilizer (Pos-Con); 60% CM + 40% CF (High-CM); 30% CM + 70% CF (Low-CM); 60% PM + 40% CF (High-PM), and...