High Rate of Nitrogen Fertilization Increases the Crop Water Stress Index of Corn under Soil Drought

Abstract

Soil nitrogen (N) availability is dominated by soil water regime and the N fertilizer levels, which affect crop growth in soil water stress. To determine the optimum N applications under different degrees of soil drought, this study investigated the effects of N fertilizer levels on the crop water stress index (CWSI) of summer corn under soil water stress. A 2-year field experiment was conducted in waterproof plots in upland red soils in subtropical China. Three N fertilizer levels and seven soil water deficit levels were employed in 2007 and 2008. Nitrogen fertilization had no influence on the CWSI of the corn under slight to moderate soil drought, but the high-N treatment increased the CWSI significantly (P < 0.01) under soil drought when the mean CWSI exceeded ∼0.20. The results suggested that for scheduling irrigation or predicting crop yields, the equations between CWSI and yield should be established on comparable N fertilization levels.

Keywords:

• Corn
• crop water stress index
• N fertilization
• soil drought
• water and nitrogen interaction

Acknowledgments

This study was financially supported by the National Science Foundation (No. 40871139) and the National Key Technology R&D Program (No. 2009BADC6B01) of China.