Corn leaf water potential and water use efficiency under three conservation tillage systems

Abstract

Corn ( Zea mays L.) was grown using three conservation tillage (CT) systems: till-plant (TP), chisel (CH) and no-till (NT), and conventional moldboard plow (CN) on two soils (silt loam and loamy sand). These tillage systems were compared for soil water storage capabilities, leaf water potential, dry matter and grain yield production per unit of water depleted. Soil water storage ranked NT > CH > TP > CN throughout the growing season in all profile segments for both soils with the exception of the 0.25–1-m zone in 1984 for the silt loam soil, where soil water storage ranked NT > CN > TP > CH. Greater water storage differences betweenthe CT systems and CN was found for deeper depths (> 0.75 m) in the loamy sand soil. Leaf water potential for both sites ranked NT > CH > TP > CN, indicating higher water stress for corn grown with CN compared to NT. In a relatively dry year such as 1983, the dry matter per unit of water depleted was 72.3, 64.3, 60.1 and 59.6 kg ha −1 mm −1 for CH, NT, TP and CN, respectively, for the silt loam site. Although no significant differences were detected, the dry matter production per unit of water depleted from NT was higher than CH, TP and CN by 1.1, 10.2 and 12.4%, respectively, in 1983 for the loamy sand site. Grain yield per unit of water depleted was not significantly different in all years and soil types with the exception of 1983 on the loamy sand soil where NT, CH and TP were higher than CN by 20.8, 12.9 and 14.6%, respectively. The greater amounts of water stored with the CT systems eliminated the potential for reduction in dry matter and grain yield with these systems due to lower soil temperature early in the growing season.