|Williford, Julius - Ray|
Submitted to: American Society of Agronomy Meetings
Publication Type: Proceedings
Publication Acceptance Date: 10/25/2001
Publication Date: 10/25/2001
Citation: SASSENRATH COLE, G.F., WILLIFORD, J.R., HOOD, K.B., THOMSON, S.J. DELINTING EDAPHIC AND BIOTIC FACTORS CONTRIBUTING TO YIELD AND QUALITY VARIABILITY IN COTTON. AMERICAN SOCIETY OF AGRONOMY MEETINGS. 2001. Interpretive Summary: In today's agriculture, increasing costs and decreasing returns are making it increasingly difficult for farmers to succeed. This research outlines a management approach that examines the production system, and develops management options that are optimal for given limitations in the production system. The key points of the approach are to identify the regions of variability within the field, identify the primary limiting factors contributing to that variability, develop a strategy of control, and finally, test the potential economic return of the management strategy. This approach was implemented on a small field in a large production setting. Soil variability from soil texture and elevation resulted in a difference in potential profitability in excess of $200 per acre. The presence of a sand lens within the field contributed to excessive drainage and nutrient leaching. This sand lens had good stand establishment early season due to the very friable nature of the soil. However, the excessive nutrient leaching and lack of adequate moisture severely reduced the yield, and subsequent profit of this portion of the field. Conversely areas that had heavier soils with poor drainage retained excessive moisture early season, hampering stand establishment. The optimal areas of the field had good drainage, and adequate moisture mid-season. Future research efforts are exploring possible site-specific management strategies to ameliorate the discrepancies in soil regions.
Technical Abstract: The alluvial flood plains of the lower Mississippi River are nutrient rich, geographically young soils deposited during cyclical flooding and drying episodes. Efforts to put the land into production have led to drainage of the swamps, particularly during the last 100 years. These natural and man-made events have resulted in rich agricultural fields of highly variable soils. The soils within a given field may range from excessively drained silt loams and loamy sands of recent natural levees to the poorly drained silty clay loams and clays found chiefly in slack water areas. Very minor differences in elevation can accentuate differences in soil drainage characteristics. While these soils are potentially high yielding, the considerable variability in soil drainage and nutrient characteristics make them difficult to manage. This study delineated soil and environmental limitations to optimal yield and quality in a cotton production system. Primary differences in yield result from the water holding capacity of the soil. Excessively drained areas were found to have poor nutrient levels due to extensive leaching. While the germination efficiency was excellent on these highly friable soils, the low nutrient levels were insufficient to sustain adequate crop growth through the growing season, and yield was markedly reduced. The slowly draining areas, while nutrient rich, held excessive moisture, resulting in reduced germination and poor stand establishment. Regions of the field of intermediate drainage had a good yield potential. Notable differences in profit margin were observed for the various regions of the field. Future research is targeted at developing management scenarios that will tailor the input costs to the anticipated yield potential through development of prescriptions to manage the variant soil characteristics in a spatially accurate manner.