Temporal and Spatial Influence of Perennial Upland Buffers on Corn and Soybean Yields

Contour perennial buffers within cropland reduce pollutants from watersheds, but may interfere and affect crop yields at the crop-buffer interface. The objective of this study was to evaluate the temporal and spatial effects of agroforestry (AGF) and contour grass (CGS) buffers on no-till corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] yields in the claypan region of Missouri. The CGS buffers (4.5-m width) contained redtop (Agrostis gigantean Roth), brome grass (Bromus spp.), and birdsfoot trefoil (Lotus corniculatus L.), established at 35 m spacings. The AGF buffers contained, a single row of pin oak (Quercus palustris Muenchh.), swamp white oak (Q. bicolor Willd.), and bur oak (Q. macrocarpa Michx.) trees planted at 3-m spacings in the middle of grass strips. Mean yields of corn in 2004, 2006, and 2008 and soybean in 2005, 2007, and 2009 at distances 0 to 5 m, 5 to 10 m, 10 to 15 m, and 15 to 20 m from AGF and CGS buffers were determined using geo-referenced yield maps and ArcGIS software. Corn yield reductions at 0 to 5 m from buffers, ranged from 22 to 49% in AGF and 15 to 32% in CGS watersheds, compared to the yield at 15 to 20 m during 2004 and 2006. This reduction may have been enhanced from soil moisture stress, late planting, and different hybrids between study years. Soybean yields were not affected by buffers. Reduction of corn yields could be potentially minimized with early planting, drought-tolerant varieties and reduction of buffers root competition with pruning or barriers.