Water storage, soil temperatures and maize (Zea mays L.) growth for various tillage practices

Four tillage treatments ranging from conventional mouldboard ploughing through to direct-drilling were repeated during the second season of an ongoing experiment. At commencement of the new season, differences in plant- available water (PAW) in the top 600 mm of the soil profile were non-significant. Following primary tillage, a strong trend of lower PAW with increasing degree of tillage was observed until just before anthesis, and again midway through grain-filling. These differences were attributed mainly to reduced evaporation prior to planting under the greater maize residue cover on the less disturbed soil. Residue cover at planting was 83% on the direct-drill, 21% on the chisel, 15% on the chisel & disc, and 4% on the mouldboard ploughed treatments. Maximum soil temperatures at 50 mm depth increased with decreasing residue cover which resulted in quicker seedling emergence, and leaf area development during early vegetative growth. The soil water storage advantage and slower initial growth in the direct-drill treatment was associated with highest yield of 7,6 t ha −1 .