SOIL MANAGEMENT, TERRAIN ATTRIBUTES AND SOIL VARIABILITY IMPACTS ON COTTON YIELDS

Authors: TERRA, JOSE - AUBURN UNIVERSITY; Reeves, Donald; SHAW, JOEY - AUBURN UNIVERSITY; Raper, Randy; VAN SANTEN, EDZARD - AUBURN UNIVERSITY; MASK, PAUL - AUBURN UNIVERSITY

Submitted to: International Soil Tillage Research Organization Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/14/2003
Publication Date: 7/14/2003
Citation: Terra, J.A., Reeves, D.W., Shaw, J.N., Raper, R.L., Van Santen, E., Mask, P.L. 2003. Soil management, terrain attributes and soil variability impacts on cotton yields. In: Proceedings of the 16th International Soil Tillage Research Organization (ISTRO) Conference, July 13-18, 2003, Brisbane, Australia. p. 1217-1222.

Interpretive Summary: Crop yields and farm profits are often reduced in some areas of fields with lower soil quality and productivity. In order to better understand and manage this variability, we conducted a field-size experiment in east-central Alabama using soil survey, geo-referenced elevation, and electrical conductivity to map field variability. A corn-cotton rotation used either of two systems: a conventional system (chisel plowing and no winter cover crop) or a conservation system (no-till) with legume and small grain covers. Three management zones in the field were produced by combining layers of information from the mapped terrain and soil features. Conventional system yields were always less than conservation system yields, regardless of management zone. Additionally, the conservation system reduced yield variability; especially in drier years and in management zones with inherently lower yield potential. This information demonstrates the benefit of conservation systems to increase cotton yields, especially under drought stress. Additionally, fewer and simpler zones may be needed under conservation management practices than under conventional to effectively manage field variability. This information can be used by extension, NRCS, and private-sector consultants to promote the use of conservation systems that optimize inputs and profits for crop production.

Technical Abstract: The ultimate goal of site-specific agriculture (SSA) is to optimize inputs for agronomic and environmental benefits. Soil and yield variability and their interaction with soil management practices are required to understand cause-effect relationships. However, these interactions have rarely been assessed at the landscape level. Our objective was to evaluate two years of cotton (Gossypium hirsutum L.) seed yield response to soil management practices and the interactions with terrain and soil attributes. A soil survey, topography, and soil electrical conductivity (EC) maps were obtained to delineate management zones. Composite soil samples (30 cm depth) were collected from 496 cells and analyzed for soil organic carbon (SOC) and texture. Four treatments were established in a randomized complete block design with 6 replicates in 6-m wide strips traversing the landscape in a corn (Zea mays L.)-cotton rotation. Treatments were a conventional system with (CTM) or without dairy bedding manure (CT), and a conservation system with (NTM) and without manure (NT). Conventional systems yields were 10% lower than conservation systems in 2001 (2836 vs. 3122 kg ha-1) and 19% lower in 2002, which was drier. Neither manure nor the treatment*year interactions were statistically significant. Accounting for spatial correlation reduced standard errors of treatment means, making the manure effect and the interaction manure*management system significant. Slope, EC, SOC and clay affected yield in all management systems and R2 ranged between 0.25 and 0.62. The conservation system was more productive in all environments that resulted from the combination of two years x three management zones created. The conservation system has greater impacts in dry years and in management zones with lower yield potential.