Disk-till vs. no-till maize evapotranspiration, microclimate, grain yield, production functions and water productivity

Recognition and understanding of impacts of any crop and (or) soil management practice on crop water use is equally crucial as its intended impacts. One such practice that has gained adoption among producers in the U.S. maize growing regions is conservation tillage, aiming at maintaining about 30-40%, or more, of residual vegetative cover on the soil surface after planting. The presence of numerous interacting factors suggests that the success of this practice is subject to its effectiveness on local scales, requiring scientific/research-based data. The crop evapotranspiration (ETc), microclimate, yield, water productivity (WP) and other variables for irrigated maize (Zea mays L) were measured and compared under disk-till (DT) (conventional) and no-till (NT) (conservation) tillage systems in 2011, 2012 and 2013 in two carefully managed and monitored producers' fields, which have been under these tillage management practices for over 17 years. On a three-year total basis, the DT maize ET, (2091 mm) was 92 mm higher than the NT maize ETc (1999 mm). Also, a seasonal and a monthly pattern existed in the difference between DT and NT ETc. NT maize had less pre-anthesis water use than DT maize and greater post-anthesis water use than DT maize in all three growing seasons. The irrigation-yield (IYPF) and evapotranspiration-yield production functions (ETYPF) were developed, and change in ETc increase per unit irrigation application was quantified for both DT and NT maize. Differences in ETc between the two tillage systems was also responsible for modification of field-scale microclimate, where the difference in ETc between the two fields was negatively related to differences in air temperature, vapor pressure deficit, wind speed and sensible heat flux, whereas it was positively related to net radiation and total soil-water. Maize yield was higher for DT maize than NT maize for all three years, by 7% (0.8 t/ha), 6% (0.8 t/ha) and 10% (1.2 t/ha) for 2011, 2012 and 2013, respectively. Tillage practice did not impact WP as WP for both tillage practices were similar, ranging from 1.74 to 1.94 kg/m(3). The presented research data and information are a benchmark evidence for tillage-specific agricultural water management for stakeholders in regions with similar crop management and climatic conditions.