Source-Dependent Effects of Organic Fertilizer Substitution on Rice Yield, Grain Quality, and Soil Properties in a Paddy System

Organic fertilizer substitution is increasingly used to reduce chemical nitrogen input in rice production, but the agronomic effects may vary with fertilizer source. This study compared chemical fertilizer alone with seven organic substitution treatments based on rapeseed cake, peanut bran, mushroom residue fertilizer, cattle manure, chicken manure, goat manure, and pig manure under the same nitrogen substitution ratio. Rice yield, grain quality, post-harvest soil physicochemical properties, and integrated performance were evaluated in the 2025 final-year dataset after two consecutive years of continuous fertilization. Responses differed clearly among fertilizer sources. Chicken manure and cattle manure produced the highest grain yields, mainly through stronger effects on grains per panicle, seed-setting rate, and grain filling. Grain quality showed more selective responses: mushroom residue fertilizer resulted in the highest head rice rate, peanut bran increased chalkiness-related traits, and mushroom residue fertilizer and goat manure were associated with higher grain protein content. In contrast to the yield pattern, plant-derived fertilizers, especially rapeseed cake and mushroom residue fertilizer, showed stronger advantages in post-harvest soil improvement. Rapeseed cake produced the highest soil quality index, whereas mushroom residue fertilizer showed the most balanced overall performance across yield, grain quality, and soil variables. These results indicate that the effects of organic fertilizer substitution in rice are strongly source-dependent. Animal-derived fertilizers were more favorable for short-term yield improvement, rapeseed cake was more effective for soil fertility enhancement, and mushroom residue fertilizer provided the best overall balance among productivity, grain quality, and soil improvement.