Soil Variability and Management Effects on Coastal Plain Corn Yields.

Soil management impacts on crop productivity have rarely been assessed on the field-scale, especially for Coastal Plain soils of the Southeast.  We evaluated soil management practices effects on corn (Zea mays L.) yield in a 9-ha AL coastal plain field (Typic and Aquic Paleudults) during 2001-2005. Treatments were established in a randomized complete block design in strips crossing the landscape in a corn-cotton (Gossypium hirsutum L.) rotation. Treatments were: a conventional management system with or without dairy manure (CTM or CT), and a conservation management system with and without manure (NTM or NT). In conventional systems, tillage consisted of chisel plowing/disking + in-row subsoiling; no cover crop was used. Conservation systems consisted of no surface tillage with non-inversion in-row subsoiling and winter cover crops.  Overall corn yields were greater three out of the five year experimental period, which can be attributed to favorable rainfall.  Corn yields from conservation management systems (NTM or NT) were approximately 11% greater than corn yields from conventional management systems (CTM or CT) averaged over the 5-year experimental period.  Conservation systems (NTM or NT) also produced higher corn yields across each landscape position (summit, sideslope, and drainageway) compared to conventional systems (CTM and CT).  These results indicate that conservation systems can enhance corn yields across highly weathered and subsequent highly variable fields of the Southeast under dryland conditions.