Short-term effects of tillage and leaf mulch on soil properties and sunflower yield under semi-arid conditions

A study was conducted at the University of Venda Experimental Farm, Limpopo province, South Africa to determine the effects of tillage and mulching on selected soil properties, and yield of sunflower (Helianthus annuus L.). The experiment was laid out in a split plot design with three replications during the 2018/19 and 2019/20 cropping seasons. Treatments consisted of conventional tillage (CT) and minimum tillage (MT) and three levels of avocado leaf mulch (0, 6 and 12 t/ha). Bulk density (BD), aggregate stability (AS), infiltration rate (IR), soil water content (SWC) and grain yield were determined. Tillage had no significant effect on BD in either season but influenced SWC and sunflower grain yield. CT recorded a significantly higher AS than MT during 2018/19 cropping season. Tillage x mulch interaction was significant during 2018/19 season with CT at 12 t/ha mulch recording higher AS than the MT. IR was significantly influenced by tillage x mulch interaction in both seasons with MT recording higher IR than the CT during 2018/19. Avocado mulch had no significant effect on sunflower grain yield in either season but influenced SWC in 2019/20 season. It was concluded that avocado mulch could be a relevant component of conservation agriculture but long-term studies are needed to validate the benefits observed in this study.