Temporal and Spatial Yield Differences Influenced By Riparian Buffers and CRP.

Despite water and soil quality improvements from use of riparian buffers and the Conservation Reserve Program (CRP), they can reduce crop yields, especially at the tree/CRP-crop interface and progressively at increasing distances from that interface with time.  The objective of this study was to quantify temporal and spatial yield differences in a no-till corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation in association with a mature multi-species riparian buffer, CRP, and root pruning (RP).  Corn and soybean yields were determined by rows from 2007 to 2010 with three replications using a small plot combine and analyzed in a split-plot in space and time design.  Regression analysis was used to evaluate yield differences among years and distances from the tree/CRP-crop interface and RP.  Yield at row nearest the interface (row 1) was 97, 97, 65, and 67% lower than the yield at 9.1 m away from the interface (12^th row) in 2007, 2008, 2009, and 2010, respectively.  Averaged across four years corn yields at row 1 was 63, 78, and 81% of that at row 4, 8, and 12, respectively.  CRP had no effect on corn yields.  Effects of the riparian buffer and CRP were inconclusive for soybean yields.  The root pruning treatment showed increasing yields for rows away from the tree interface for both corn and soybeans.  The row number explained 21-60% and 15-52% of the yield variations in corn and soybean, respectively.  Results of the study suggest selection of low resource demanding crops such as soybean for use in the first 12 rows or use of CRP management that can generate additional income and ecosystem services.