Optimizing Agronomic Practices for Clover Persistence and Corn Yield in a White Clover–Corn Living Mulch System

Abstract

Core Ideas Living mulch cover crops help stabilize erosive soils during corn production. Wide rows enable the living mulch cover crop to re‐establish for subsequent cropping. Herbicide bands must be kept to a minimum width to permit living mulch. Removal of crop residue is essential for white clover to perenniate in the living mulch system. White clover can supply over 100 kg ha−1 N to corn in the living mulch system. The area dedicated to corn (Zea mays L.) production increased 50% in the southeastern United States between 2006 and 2016, but producers need to find production systems that mitigate environmental impacts on erosive soils. Utilizing a perennial legume in a living mulch system may help stabilize the soil. The objectives of this study were to identify the most successful herbicide banding pattern (20 or 40 cm), corn row spacing (75 or 90 cm), and corn population density (60,000 or 90,000 plants ha−1) to optimize potentially mineralizable nitrogen (PMN) from white clover (Trifolium repens L.) and maximize clover regrowth in a living mulch system. Plots were established at Floyd and Oconee Counties, Georgia, and tested over 2014 and 2015. Clover persistence and regrowth was best when initial clover suppression used a 20‐cm band and corn was planted on 90‐cm rows. Herbicide‐induced PMN was greater for the wide herbicide band width, but shade‐induced PMN was greater from the narrow band width. Corn shaded the clover at approximately 40 d after planting (DAP) and clover responded by senescing biomass as shading increased. Shading resulted in the majority of PMN regardless of other treatments variables. Corn grain yields were greater in the high population treatments, but there was a year × location × herbicide band width interaction. Considering clover persistence, PMN, and corn grain yield, we conclude that corn planted on 90‐cm rows in 20‐cm wide herbicide bands of dead clover is the best treatment for the living mulch system.

Nitrogen Dynamics in Living Mulch and Annual Cover Crop Corn Production Systems

“…Sanders et al (2017) developed a planting configuration within the white clover LM system, which promotes re-establishment of clover following a corn crop so that subsequent crops can take advantage of fixed legume N rather than depend on fertilizer N. Their study was conducted on thermic soils in the humid, southeastern United States, whereas other LM studies were conducted on temperate mesic or frigid boreal soils (Rasse et al, 1999;Tonitto et al, 2006;Nakamoto and Tsukamoto, 2006;Zemenchik et al, 2000). Mineralization conditions for organic matter at the soil surface are likely to be greater under thermic conditions found in the humid, southeastern United States, making comparisons to other LM systems difficult (Quemada and Cabrera, 1997).…”

“…Mineralization conditions for organic matter at the soil surface are likely to be greater under thermic conditions found in the humid, southeastern United States, making comparisons to other LM systems difficult (Quemada and Cabrera, 1997). However, mineralization in the LM system described in Sanders et al (2017) may be similar to other corn production systems commonly used on thermic soils in the southeastern United States, though no comparison has been made. Nitrogen availability in the white clover LM system has not been studied and is likely dependent on environmental variables affecting N mineralization and competition between the corn and intercropped clover.…”

“…The cultivars Wrens Abruzzi CR and Dixie CC were seeded by hand using the University of Georgia recommended rates of rates of 100 and 28 kg ha -1 , respectively (USDA-NRCS, 2015). The cultivar Durana white clover was planted at a rate of 13 kg ha -1 in accordance with the LM system developed by Sanders et al (2017). All plots were planted on 17 Oct. 2014.…”

“…Cover crops are one way of preventing soil erosion and providing supplemental N to a row crop (Schomberg et al, 2006) and crimson clover (Trifolium incarnatum L.) (CC) and cereal rye (Secale cereale L.) (CR) cover crops are used in the southeastern United States because of their ease of establishment, rapid growth, or ability to fix atmospheric N for subsequent row-crop use (Snapp et al, 2005;YoungMathews, 2013). Recent attempts have been made to use a living mulch (LM) system in corn (Zea mays L.) to provide supplemental N and provide protection against soil erosion (Zemenchik et al, 2000;Sanders et al, 2017). Perennial living mulches are crops planted either before or with a main crop and maintained throughout the growing season, as opposed to annual cover crops that are terminated prior to planting (Hartwig and Ammon, 2002).…”

“…The reasoning of the concept was to offset the polluting potential of N fertilizer as well as reduce the fossil fuel demand required for NH 3 production via the Haber-Bosh process (Smil, 1997). Vegetable growers were the primary early adopters of LM systems (Paine and Harrison 1993), but recently interest has been emerging among grain crop producers (Rasse et al, 1999;Zemenchik et al, 2000;Duda et al, 2003;Nakamoto and Tsukamoto, 2006;Kramberger et al, 2009;Sanders et al, 2017). A concern with use of LM systems is the potential of a perennial cover crop competing with the cohabitating row crop (Kurtz et al, 1952;Zemenchik et al, 2000;Affeldt et al, 2004).…”