Influence of density correction on latent heat, CO2 flux and energy balance closure in winter wheat/summer maize rotation fields Effect of long-term shallow tillage and straw returning on soil potassium content and stratification ratio in winter wheat/summer maize rotation system in Guanzhong Plain, Northwest China. Ammonia volatilization in winter wheat/summer maize rotation system of purple soil in hilly area of Central Sichuan Basin Soil N2O emission in contour hedgerow/crop intercropping system in subtropical China RZWQM simulation of nitrogen transport and loss under winter wheat/ summer maize rotation system in the North China Plain