Changes in Soil Hydraulic Properties Under Long-Term Tillage and Cropping Systems in the Central Great Plains.

Understanding of soil-water relations is of paramount importance to agronomic production particularly in regions of low water precipitation such as the U.S. Great Plains. A comprehensive characterization of management-induced changes in soil hydraulic properties is critical to evaluate performance of tillage and cropping systems for favoring an efficient use of precipitation water. Improved management practices (e.g., no-till) which leave crop residues on the soil surface can promote water intake and storage because residue cover reduces water evaporation and protects soil surface from surface sealing and crusting by raindrop impacts. Published data show that the impacts of tillage, crop, and residue management systems on soil hydraulic properties in the Great Plains are variable and site specific. An integration of measured and modeled data on soil hydraulic behavior from long-term experiments across a broad range of soils is needed to discern the potential of management systems such as no-till for improving water movement, retention, and availability in the region. It is also important to understand the temporal variability in hydraulic properties (e.g., water infiltration) to diagnose the seasonal distribution and storage of precipitation. Thus, this ongoing study set out to characterize the impacts of long-term tillage and cropping systems on soil hydraulic parameters under long-term experiments in western Kansas. Parameters including water infiltration, saturated and unsaturated hydraulic conductivity, water retention characteristics, plant available water, and soil pore-size distribution are being evaluated to describe soil-water dynamics. Pedotransfer functions will be used to predict the hydraulic properties for the study soils. Results will be reported and discussed at the meetings.