Surface Runoff and Lateral Subsurface Flow as a Response to Conservation Tillage and Soil-Water Conditions

Conservation tillage has significant potential as a water management tool for cotton production on sandy,drought-prone soils. Plant residue remaining at the soil surface from prior crops serves as a vapor barrier against water loss,reduces raindrop impact energy, slows surface runoff, and often increases infiltration. By increasing infiltration, the potentialfor greater plant-available water can be enhanced and irrigation requirements reduced. Five years of data were collectedto quantify the hydrologic differences between strip till and conventional till production systems. Surface runoff and lateralsubsurface flow were measured on six 0.2 ha plots in South Georgia in order to quantify the water-related effects ofconservation tillage. Significant differences in surface and subsurface water losses were observed between the conventionaland strip tilled plots. Surface runoff from the conventionally tilled plots exceeded that from the strip tilled plots, whilesubsurface losses were reversed. Surface runoff losses from the conventionally tilled plots exceeded those from the strip tilledplots by 81% (129 mm/year). Shallow lateral subsurface losses from the strip tilled plots exceeded those from theconventionally tilled plots by 73% (69 mm/year). Overall, a net annual gain of 60 mm of water was observed for the striptilled plots.