Tillage and planting system effects on corn emergence from Norfolk loamy sand
Karlen, D.L.
Nonuniform emergence and slow, early season growth of corn (Zea mays L.) have been consistent problems for conservation tillage (CT) in southeastern Coastal Plain. Low soil temperature often causes similar problems in the Corn Belt, but previous research showed that it was not the problem. The effects of preplant tillage and various CT planting systems on seedbed water content and corn emergence were measured in one laboratory and five field studies that were conducted on Norfolk (Typic Paludult) loamy sand. Seedbed water content and seedling emergence were measured frequently after planting. Without prior disking to kill winter weeds, seedbed water content was significantly lower in three of five studies, and seedling emergence was slower in four studies. The laboratory experiment confirmed that emergence was slower when seedbed water content was less than 50 g/kg (5%). Applying irrigation water within 24 hours after planting increased emergence from CT treatments in one study, but decreased it in another because of surface crusting. Using in-row subsoil planting systems that prepare good seedbed conditions, and planters designed for rough seedbeds improved seedling emergence in CT treatments. Results show that factors affecting seedbed water content can explain emergence and stand establishment problems better than soil temperature for CT systems on sandy Coastal Plain soils.
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