Corn-soybean intercropping and nitrogen rates affected crop nitrogen and carbon uptake and C:N ratio in upland red soil

AbstractThe objective of this research was to determine the effect of corn-soybean intercropping and nitrogen rates on crop biomass, nitrogen (N) and carbon (C) accumulation, and crop C:N ratio in upland red soil. Crop dry matter yields, nitrogen and carbon contents (including grain, straw and root) were measured. Compared with sole corn, corn dry matter yield and carbon accumulation decreased in intercropped soybean. Intercropping decreased the corn C:N ratio, whereas it increased soybean C:N ratio. Nitrogen application significantly increased corn yield, nitrogen and carbon accumulation, but reduced those of soybean. Nitrogen application decreased corn straw C:N ratio and increased soybean straw C:N ratio in most intercropping systems. In conclusion, intercropping and nitrogen rates affected the growth of corn and soybean, changed the allocations of nitrogen and carbon, and altered C:N ratios in different parts of the crops.