Conventional vs. No‐Till Corn Following Alfalfa/Grass: Timing of Vegetation Kill

Abstract

AbstractProducers who plant no‐till corn (Zea mays L.) following hay or pasture are concerned about herbicide application timing and efficacy to kill perennial vegetation, plant residue effects on corn growth, and optimal corn planting date. A field study was conducted near Arlington, WI, from 1985 to 1988 to evaluate the influences of (i) conventional (CT) vs. no‐till (NT), (ii) fall vs. spring kill of perennial vegetation, (iii) late‐April vs. mid‐May planting, and (iv) three hybrid maturities on corn following legume/grass sod. Parameters measured include residue cover, soil temperature, and soil moisture after planting; corn emergence percentage; days to emergence; days to silk; grain moisture; and grain yield. Tillage by time of vegetation kill interactions were important for corn development and grain yield. Few differences were observed between fall and spring plowing in CT. For NT, however, chemically killing perennials in the spring compared to in the fall resulted in greater residue cover after planting (6–90% vs. 40%), and cooler and drier soil in the seed zone after planting. Emergence was delayed 1.5 to 4.0 d with spring‐kill NT and subsequent development was delayed throughout the growing season. Spring‐kill NT resulted in lower grain yields (−10 to −50%) compared to fall‐kill NT in 3 of 4 yr. For NT, when perennial vegetation was killed in the fall and corn was planted early, plant growth and grain yields were comparable to those for CT. Fall‐kill NT produced consistent growth and yield responses during the study years, whereas spring‐kill NT results were more variable, with poorest results in the drought of 1988.