Modeling Soil Type Effects to Improve Rainfed Corn Yields in Northeast China

Understanding how soil type in the Corn Belt of Northeast China affects both the potential yield of a rainfed crop [Yp(r)] and the yield gap [YG(r)] between Yp(r) and the water non-limiting potential yield (Yp) is essential for enhancing corn (Zea mays L.) production and identifying critical irrigation windows for different soil types. The Root Zone Water Quality Model 2 (RZWQM2) was calibrated and validated based on 2 yr of experimental data and then used to estimate Yp and Yp(r) along with YG(r) in aeolian sandy soil vs. black soil using the same weather data from 1980 to 2012. The values for Yp were the same for both soil types, and the mean Yp was 11.299 Mg ha–¹ (CV of 15.6%) during the 33-yr simulation period. The mean Yp(r) was lower in the aeolian sandy soil (7.628 Mg ha–¹, CV of 39.8%) than in the black soil (8.893 Mg ha–¹, CV of 34.5%). The mean YG(r) was 3.672 Mg ha–¹ in the aeolian sandy soil and 2.406 Mg ha–¹ in the black soil. Values for Yp(r) were positively correlated with precipitation in June and July in the aeolian sandy soil and in July in the black soil. The YG(r) was negatively correlated with precipitation in June and July in both soils. Therefore, soil type affected Yp(r) and YG(r) through the soil water condition under the same weather conditions. The critical irrigation window to decrease YG(r) is in June and July for aeolian sandy soils and in July for black soils.