Ridge-Furrow Planting System and Wheat Straw Mulching Effects on Dryland Sunflower Yield, Soil Temperature, and Moisture

The current study uses 2-yr trial data set to investigate the impacts of ridge-furrow planting system and wheat (Triticum aestivum L.) straw mulching on sunflower (Helianthus annuus L.) yield and some soil parameters. Field experiments were conducted in 2014 and 2015 in two different locations (Tehran and Mashhad Provinces, Iran). The experiments were laid out in a randomized complete block design comprised of four treatments, including control that is, neither ridge-furrow planting system nor wheat straw mulching (RF0M0); ridge-furrow planting system without wheat straw mulching (RF1M0); ridge-furrow planting system with wheat straw mulching only covering 50% of the soil surface (RF1M50); and ridge-furrow planting system with full covering (100%) of the soil surface with wheat straw mulch (RF1M100). The RF1M0 treatment could not increase sunflower yield, but the application of 50 and 100% wheat straw mulch significantly increased seed yield by10 and 18%, respectively. For both years and sites, on average the maximum seed yield was found with the RF1M100 treatment (1629 kg ha(-1)), while the minimum value (1318 kg ha(-1)) was related to RF0M0 treatment. Wheat straw mulching reduced soil temperature and increased soil water storage, organic C and microbial biomass C. We concluded that the ridge-furrow planting system with full coverage of the soil surface with wheat straw mulch could be critical in the cultivation of sunflower under arid and semiarid areas, where water is the most important factor in determining plant growth and yield.