ABSTRACT

Soil compaction management in the southeastern U.S. relies heavily on the use of annual deep tillage. The conventional cotton production systems in this area require a minimum of three and often five field operations at a cost of approximately $31 per acre. Strip tillage systems have shown considerable promise for reducing the energy and labor requirement, equipment cost, soil erosion and cotton plant damage from blowing sand. Cost savings of approximately $20 per acre could be achieved by strip tillage compared to conventional methods. This research was conducted to evaluate the performance of three different strip tillage systems compared to conventional and no-till methods in terms of effects on soil parameters, crop responses, and energy requirements; and to investigate the feasibility of eliminating the need for annual deep tillage by planting cotton directly into the previous years subsoiler furrow and controlling traffic. Replicated field experiments were conducted during the 2002 and 2003 growing seasons at Clemson University's Edisto and Pee Dee Research & Education Centers. Tillage treatments included: conventional tillage, straight shank strip-till, bent-leg shank strip-till (Paratill), bent-leg shank strip till (Terra Max), and no-till. At Blackville, the treatments were compared side by side with and without irrigation. In 2003, the test plots from previous year were split in half to determine the residual effects of different tillage systems. No deep tillage was applied to one-half of the plot while the other half received the same tillage treatment as in 2002.

At Edisto, deep tillage significantly reduced soil compaction in crop rows compared to no-till. Strip till systems utilizing Paratill and Terra Max shanks reduced soil compaction in the non-traffic row-middles. Taproots were significantly longer in deep tillage plots than those in no-till plots in both irrigated and dry land locations. No differences in plant stand occurred among the tillage treatments. There was no difference in cotton yield between the strip-till systems and conventional tillage in either dry land or irrigated plots. Deep tillage significantly increased lint yields compared to no-till. In 2002, the yield increases from deep tillage were 15% and 26% for irrigated and dry land plots respectively. Irrigation significantly increased cotton yields compared to dry land in 2002. Averaged over all treatments, irrigated plots yielded 77% more than those on dry land. There was no difference in cotton yield between dry land and irrigated plots in 2003. There was no difference in lint yield between plots which had deep tillage operation in 2002 & 2003 and those which had tillage operation only in 2002. On average deep tillage (either in 2002 or 2003) increased lint yield by 41.5% compared to no-till system.

At the Pee Dee location, dry matter partitioning data collected at first bloom showed a significant reduction in the growth and development of plants grown in strip-till and no-till production systems compared to the conventional system. Reproductive development was also affected by tillage systems, with conventional plants developing significantly more squares and partitioning more of their dry weight into squares compared to plants grown in strip-till or no-till systems. However, these differences in early-season growth and development were not apparent near the end of boll development, with no differences in any vegetative or reproductive growth measurements found. Tillage systems had no affect on flower development or nutrient uptake throughout the growing season or on lint yield and fiber quality at the end of the season.