Water infiltration and soil water content in claypan soils influenced by agroforestry and grass buffers compared to row crop management

Agroforestry buffers have recently been introduced in temperate regions to enhance conservation of soil and water resources in row crop management. The effects of agroforestry and grass-legume buffers on in situ water infiltration relative to row crop management (RC) were assessed for a claypan soil in northeastern Missouri, USA. Infiltration rates were observed in early June in 2014 and 2015 for watersheds under corn ( Zea mays L.)-soybean ( Glycine max L. Merr.) management; these watersheds had agroforestry buffers (AGB) or grass buffers (GB). The dominant soil for the watersheds was Putnam silt loam (fine, smectitic, mesic Vertic Albaqualf). The watersheds were in no-till management and established in 1991 with agroforestry buffers and GBs implemented in 1997. Agroforestry buffers, 4.5 m wide and 36.5 m apart, consisted of redtop ( Agrostis gigantean Roth), brome ( Bromus spp.), and birdsfoot trefoil ( Lotus corniculatus L.) with pin oak ( Quercus palustris Menchh.), swamp white oak ( Q. bicolor Willd.), and bur oak ( Q. macrocarpa Michx.) trees. GBs consisted of redtop, brome, and birdsfoot trefoil. Significant differences were found among the treatments in 2014 for the sorptivity parameter for the fitted infiltration equations with the highest values for agroforestry buffers. Significantly higher saturated hydraulic conductivity values were found for the buffer treatments in 2015. Soil water content measurements were assessed over time for years 2010 and 2011 with sensors at 5, 10, 20 and 40 cm depths for the agroforestry buffer and RC areas. Water content decreased more rapidly during the summer season within agroforestry buffers relative to RC areas; however, water infiltration was higher within agroforestry buffers during the recharge period.