Effects of Biogas Slurry Application on Crop Production and Soil Properties in a Rice-Wheat Rotation on Coastal Reclaimed Farmland

The field experiment of a rice-wheat rotation system was conducted on a coastal reclaimed farmland with different application rates of biogas slurry from a large-scale standardized hoggery. Crop yield, grain quality, and soil properties were examined to determine the appropriate application rate. At the slurry application rates of 480m(3)ha(-1) for rice and 9.00-11.25m(3)ha(-1) for wheat, grain yields of rice and wheat were 8.9 and 15.7% higher than those under conventional fertilization, respectively. When 840m(3)ha(-1) biogas slurry was applied to the rice field, the grain amino acid content was significantly higher than that of conventionally fertilized rice. In the rice-wheat rotation system, under biogas slurry treatments, soil pH and EC did not significantly increase; the contents of soil Pb, Cr, Cu, and Zn were within allowable limits; the contents of soil alkali-hydrolyzable nitrogen were greatly increased and significantly higher than those under conventional fertilization treatment; and the content of soil organic matter had no significant difference with that under no fertilization treatment. Therefore, the recommended application rate of biogas slurry on coastal reclaimed farmland should be 480 and 9.00-11.25m(3)ha(-1) for rice and wheat, respectively.