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

Published in Agron. J. 104:1356–1362 (2012) Posted online 10 July 2012 doi:10.2134/agronj2012.0081 Copyright © 2012 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. D adoption of conservation management practices, agricultural nonpoint-source pollution (NPSP) continues to degrade water quality (USEPA, 2010). Inter-planting AGF and/or CGS buffers within crop or pasture land has been found to trap and reduce sediment, nutrients, herbicides, animal waste, and antibiotic losses in runoff water before entering surface water bodies (Bharati et al., 2002; Abu-Zreig et al., 2003; Udawatta et al., 2002, 2010, 2011; Dosskey et al., 2007; Schultz et al., 2009). Agroforestry is defined as an “intensive land management practice that optimizes the benefits (physical, biological, ecological, economic, and social) arising from biophysical interactions created when trees and/or shrubs are deliberately combined with crops and/or livestock” (Garrett et al., 1994). The AGF practices in the United States and Canada are classified into five main categories by the Association for Temperate Agroforestry (Mervin, 1997): riparian and upland buffers, windbreaks, alley-cropping, silvopasture, and forest farming (Gold and Garrett, 2009). Upland buffers are established within the crop land along contours to reduce slope length and steepness, improve internal drainage, enhance infiltration, reduce runoff, trap sediments and NPSPs, and create wildlife habitat and connective travel corridors (Omernick et al., 1981; Schmitt et al., 1999; Qiu, 2003; Udawatta et al., 2002; Schultz et al., 2009; Gold and Garrett, 2009). Inclusion of trees in AGF buffers integrates long-term environmental benefits of forest ecosystems such as improved soil physical properties, moisture storage capacity, soil quality, and carbon sequestration into agricultural land (Seobi et al., 2005; Kumar et al., 2008; Jose, 2009; Udawatta et al., 2006, 2009; Anderson et al., 2009). Existence of a claypan at shallow depths of soils in the Major Land Resources Area (MLRA) 113 of the Central Claypan Region (USDA NRCS, 2006) in Central United States restricts downward water movement and accelerates surface water runoff and NPSP losses from agricultural watersheds (Blanco-Canqui et al., 2002). A long-term paired watershed study conducted in the Northeast Missouri claypan region with CGS and AGF buffers in a corn–soybean rotation has shown significant reductions in sediment, total N, and total P after 11 yr of establishment (Udawatta et al., 2002, 2011). For adoption of CGS and AGF buffers by farmers to protect land productivity and reduce NPSP, the impact of grain yield reductions due to competition between buffer plant species and crops needed to be investigated. The sensitivity of corn yields to soil moisture has been found to be related to the variety and the stage of growth (Wilson, 1968; Claassen and Shaw, 1970; Doorenbos and Kassam, 1979). Cakir (2004) reported that a short-duration of water deficit during the AbStrAct