Effect of Residue Management and Tillage on Corn and Soybean Yields in Rotations.

Mississippi producers continue to investigate production mechanisms for increased profitability through increased yields or decreased cost per production unit.  Primary costs of production include seed, fertilizer, and pesticides along with primary tillage, field preparations and in-season tillage practices.  Over the last half century, producers have moved toward less primary tillage and more chemical control of weeds and other pests.  In the Mid-south, soils tend to be lower in organic carbon (often < 1.5% organic matter) and often have traffic pans that impede root penetration and ultimately reduce nutrient and water uptake.  Multi-year field studies were established in two Mississippi regions to examine the interaction of residue management and tillage for corn and soybean grown in a 1:1 (corn:soybean) rotation system.  Primary tillage systems included: 1) a minimum tillage system [re-shape beds as needed]; 2) bed and roll; 3) subsoil, bed, and roll [one-pass]; and 4) conventional [disk (2X) + one-pass].  Also included in the study design is a burn/no burn option for corn residue.  The research areas have been established as a split plot with the whole plot maintained as a) burn corn residue and b) no burn of corn residue.  The sub plots were the tillage treatments already outlined.  The two study locations were in the Mississippi Delta (irrigated ) and in the North Mississippi Hill area (rain-fed).  All cultural practices were consistent for each location but varied by location to incorporate irrigation.  The center two rows of each grain crop plot was harvested with samples collected to determine harvest moisture, test weight, and Seed Index (100-seed weight). The Delta location tended to require greater bed maintenance than the other location due to the nature of the sandy loam soil and the need to maintain a pathway for water movement through the field during irrigation.