Erosion and Sediment Control
30 Minute Presentation
Water Balance in Agricultural Conservation Production Systems Verses Conventional Production Systems in the Southeastern USA
Agriculture is faced with the challenge of meeting the demands of an increasing global population with the same or less amount of resources and land. As it relates to water, how effective are conservation production systems at retaining the soil moisture and reducing the volume of runoff under different conditions throughout the growing season compared to conventional systems? Soil moisture and the reduction of erosion are important factors for crop production, water conservation, and water quality. This presentation investigates the soil moisture profile and overall field specific water balance for conservation production systems versus conventional production systems at three farmer-operated sites throughout the state of Georgia. Field studies were conducted to compare the rate of soil moisture retention under conservation tillage (ST) verses conventional tillage (CT) in cotton (Gossypium hirsutum) production. Conservation production systems methods are used to prevent erosion by protecting the soil surface from high intensity rainfall events, reducing runoff, increasing infiltration and increasing soil organic matter. These reduced tillage systems are known to increase infiltration in some regions, however there is a knowledge gap on how these systems influence the soil moisture retention rate. Research was conducted on fields managed under these two systems to determine if there is a difference in the subsurface water loss rate, soil quality, and overall water balance. Experiments were conducted at three locations throughout Georgia in the counties of Oconee, Bulloch and Pulaski (two fields per county, one each of conservation tillage and one of conventional tillage). At each of the six fields in the study, soil moisture sensors were installed at 10, 20 and 30 cm depths and collected every 10 minutes. Data was analyzed to determine the rate of soil moisture loss during drying periods between rainfall events. An edge-of-field monitoring station was installed with an ISCO 6712 automated sampler to measure runoff levels. Field-specific water balance calculations were conducted based on the rainfall, drainage, crop evapotranspiration, and runoff. The water loss rates vary by location and the water content in the fields was nearly at or above field capacity for the duration of the 2018 growing season. For the collected water runoff, the CT fields lost more water per area than the ST fields. Upon visual inspection, large quantities of soil were displaced from the CT fields compared to the ST fields. This research evaluates the performance of conservation and conventional production systems in the Southeast US and can aid in the recommendation of future farming practices to better manage natural resources, reduce non-point source pollution from agriculture, and improve knowledge of these large-scale systems’ water use.