Strip-tillage and Zonal Cover Cropping Effects on Organic Squash Production

Abstract

Zonal management of cereal–legume cover crop mixtures may help address weed and nitrogen management challenges common in organic reduced tillage systems. During a field study conducted over 3 years in Michigan, we evaluated the effects of cover crop management, tillage, and supplemental mulch on organically produced acorn squash (Cucurbita pepo). During the fall season before squash production, rye (Secale cereale L.) and vetch (Vicia villosa Roth) cover crop mixtures were sown in two distinct spatial arrangements: a “mixed planting,” in which seeds were sown in the same rows, and a “zonal planting,” in which vetch was planted only in the in-row zone and rye was planted only in the between-row zone of the subsequent squash crop. During the following spring season, cover crops were mowed, and four tillage and cover crop management combinations were established: full-width tillage with the mixed planting of rye–vetch (full-till mixed); strip-till with the same mixed planting (strip-till mixed); strip-till with the rye–vetch zonal planting (strip-till zonal); and strip-till with the zonal planting and additional rye mulch added between crop rows immediately after crop establishment (strip-till zonal plus rye). The strip-till mixed treatment resulted in yields equivalent to those of the full-till mixed treatment despite lower available nitrogen and greater early weed competition in some cases. Within strip-till treatments, zonal planting of rye–vetch provided no benefits relative to full-width planting (treatment 2 vs 3) and resulted in lower total cover crop biomass, a higher density of escaped weeds, and lower squash yields during 1 of 3 years. Supplemental rye mulch improved weed suppression and yields in strip-till zonal treatments and resulted in yields equivalent to those of the full-till mixed treatment in all years, but it provided no benefits relative to strip-till mixed. Our results demonstrate that strip-till organic squash production can produce yields equivalent to full-till production in Northern climates, but that zonal planting and supplemental mulch have limited benefits for addressing ongoing weed and nitrogen management challenges. Growers must weigh costs associated with these challenges against potential benefits for soil and pest regulating ecosystem services before adopting these agricultural conservation practices.