Short-Term Influence of Crop Rotation On Wheat Yield and Alkaline-Hydrolyzable Nitrogen.

Increasing the long-term sustainability of domestic crop production has been the primary research focus within the past decade. Research has highlighted the ability of alkaline hydrolyzable-N as an indicator of potentially mineralizable soil N and it has been successfully correlated to crop response. Green manures are often used in rotation to increase productivity and lower the dependence on synthetic fertilizers, but the actual credit gained from these practices is often unknown and can lead to yield loss due to improper fertilization.  A study was initiated to determine the influence of crop rotation on alkaline hydrolyzable-N and the resultant influence on winter wheat yield and wheat response to N fertilizer. A strip-split plot design using rotation as the main plot and N rate as the sub-plot was initiated in 2006. Soft red winter wheat was grown in rotation with either a green manure crop or forage and data was collected on wheat yield and changes in soil properties including alkaline hydrolyzable-N, TN and TC. Alkaline hydrolyzable-N was significantly influenced by crop rotation and steadily increased in the green manure rotation. Wheat yield and response to N fertilizer was also influenced by rotation as the N rate required to maximize wheat yield decreased over time in the green manure rotation. Initial results suggest that alkaline hydrolyzable-N is highly correlated with wheat response to N and can be calibrated to predict N availability from green manures as well as the N rate required to maximize wheat yield in Arkansas.