Soil Water Infiltration Affected By Biofuel and Grain Crop Production Systems in Claypan Landscapes.

The effect of soil management systems on water infiltration is very crucial within claypan landscapes to maximize production as well as minimize environmental risks. The objective of this study was to assess the effect of topsoil thickness on water infiltration in claypan soils for grain and biofuel crop production systems. The study was conducted on the Soil Productivity Assessment for Renewable Energy and Conservation (SPARC) plots at the University of Missouri.  Plots were planted with either switchgrass (Panicum virgatum L.) or a corn (Zea mays L.)-soybean (Glycine max (L.) Merr.) rotation. Plots were initially established in 1982 with two levels of topsoil thickness (0 and 37.5 cm) on a Mexico silt loam (Vertic Epiaqualfs).  Ponded infiltrometer units were used to measure infiltration rates in 2014 and 2015 under switchgrass, and grain crop management each with two levels of topsoil thickness. Physically-based Parlange and Green and Ampt infiltration models were used to estimate saturated hydraulic conductivity (K_s) and sorptivity (S) parameters. Parlange and Green and Ampt models fit infiltration data well with r² values near 0.99. The estimated sorptivity (S) and saturated hydraulic conductivity (K_s) values in shallow topsoil thickness (0 cm) were lower than deeper topsoil thickness (37.5 cm) for both years (2014 and 2015).  The switchgrass treatment had greater S and K_s values compared with the row crop treatment. Results show that biofuel crop production systems (switchgrass) enhance water infiltration compared with row crop management within claypan soil landscapes.