Effect of different application levels of rapeseed meal on growth and yield components of rice

Application of rapeseed meal as organic fertilizer improves soil environment and crop productivity by supplying the nutrients. This study aimed to investigate the optimal application levels of rapeseed meal for rice cultivation. Application of rapeseed meal increased the height of rice plants by about 5-10% compared to the control, and its application at a rate of 50, 100, 200, and 300 kg/0.1 ha increased the nitrogen content in rice leaves at 30 days after treatment by 107.3, 110.4, 114.7, and 114.7%, respectively, compared to the control. In treatments with a mixture of chemical fertilizer and rapeseed meal (50, 100, 200, and 300 kg/0.1 ha), the nitrogen content in rice leaves increased by 105.1-107.7% compared to that in the control; there was no significant difference between the treatment with chemical fertilizer only and that with the mixture of chemical fertilizer and rapeseed meal. The chemical properties of soil treated with rapeseed meal at 200 and 300 kg/0.1 ha or with the mixture of 200 kg/0.1 ha rapeseed meal and chemical fertilizer (1/2 level) showed that nitrate and ammonium increased in treated soils as compared to untreated soil. The yield and yield components were positively correlated with the application levels of rapeseed meal and the mixture of rapeseed meal and chemical fertilizer. The application of rapeseed meal at 100-200 kg/0.1 ha is considered optimal, and efficient application of nitrogen is achieved by mixing chemical fertilizer (11 kg/0.1 ha) with rapeseed meal (100-200 kg/0.1 ha).