ARS | Publication request: Off-season groundcover and runoff characteristics of perennial clover and annual grass companion crops for no-till corn fertilized with manure

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 21, 2012
Publication Date: N/A

Interpretive Summary: Corn silage is the predominant forage fed to cattle in the Midwestern United States, but its production can contribute to groundwater contamination, eutrophication of natural ecosystems, and hypoxia in coastal waters by soil, phosphorus, and nitrates. The production of silage corn with companion crops (e.g. cover crops or living mulches) is therefore widely recommended for reducing soil and nutrient losses from cropland and for maintaining or improving crop yields, nutrient cycling, and soil quality. However, few studies have compared the productivity and efficacy of perennial legume versus annual grass companion crops for silage corn fertilized with manure. Therefore, we evaluated the performance of five companion-crop systems for corn amended annually with fall or spring manure. In two rotational systems, corn was grown for one year with kura clover living mulch or interseeded red clover followed by one year of clover production. Three continuous corn systems employed interseeded ryegrass, fall-seeded rye, or no companion crop. This paper describes the growth and uptake of soil nitrogen of these companion crops in the fall or spring and their potential effect on spring surface runoff and losses of phosphorus and sediment as influenced by the timing of manure application. Overall, no system was clearly superior in all attributes; thus, companion crop selection and manure management for no-till silage corn will depend on producer requirements for feed production and the need to limit soil and nutrient loss from cropland.

Technical Abstract: Various companion crops such as spring-interseeded or fall-seeded cover crops and herbicide-suppressed living mulches are recommended for reducing the environmental impacts of silage corn (Zea mays L.) production. In a four-year Wisconsin study, we compared off-season dry matter yield (DMY) and nitrogen (N) accumulation in groundcover produced by five companion crop systems for glyphosate-resistant no-till corn amended yearly with spring or fall surface-banded manure. In two rotational systems, corn was grown for one year with kura clover (Trifolium ambiguum Bieb.) living mulch or spring relay-interseeded red clover (Trifolium pratense L.) followed by one year of clover production. Three continuous corn systems utilized spring interseeded ryegrass (Lolium multiflorum Lam.), fall-seeded rye (Secale cereale L.), or no companion. Fall DMY and N accumulation in groundcover were greatest for rotationally grown clovers in forage production and interseeded ryegrass, whereas spring DMY and N accumulation were greatest for fall-seeded rye and kura clover going into corn production. Overall, the kura clover-corn rotation came the closest to providing significant DMY and N accumulation in groundcover throughout the off-season period. Shifting manure application from spring to fall mainly influenced rye by stimulating its growth under warm spring conditions. In a follow-up study, spring surface runoff and losses of phosphorus and sediment with fall manure were least with rye followed by ryegrass. Shifting manure application to spring largely negated companion crop effects on spring runoff and substantially increased loading of dissolved reactive phosphorus.