Contrasting Tillage Effects On Infiltration, Stored Soil Water and Yield At Two Locations.

The success of reduced tillage practices in improving and sustaining crop yield can be influenced by the interaction of soil and climate. A paired field study in Bushland, TX and Tribune, KS evaluated infiltration and evaporation throughout a wheat-sorghum-fallow rotation under no tillage (NT) and stubble-mulch tillage (ST) management. Near-surface (0.1 – 0.3 m) hourly soil water contents were measured at each location using time-domain reflectometry. Profile water contents were monitored weekly or bi-weekly using a neutron probe. Soil temperature, precipitation and solar radiation were also measured. Cumulative infiltration and evaporation were estimated using a water balance approach in conjunction with a calibrated drainage model. At both locations, soil water contents at 0.05 and 0.1 m were lower in recently tilled ST plots, even following repeated precipitation events. Prior to sorghum emergence, tillage reduced pre-emergence water content by 7 mm in Bushland and 60 mm in Tribune. Most of the additional stored soil water under NT was above 0.15 m depth at both locations. During fallow after sorghum in Bushland, NT did not influence cumulative infiltration and evaporation and, consequently, did not exhibit significantly improved water storage despite having greater residue cover. During fallow after sorghum in Tribune, NT significantly (P<0.06) increased infiltration compared with ST but these gains were offset by greater evaporation rates. Field areas with high residue accumulations and micro-lows contributed to the large variability in infiltration fluxes for NT at both locations. The short-term hydrologic response to tillage practices substantially differs at each location and this influences sorghum yield potential and profitable dryland cropping management practices at each location.