Buried straw layer plus plastic mulching reduces soil salinity and increases sunflower yield in saline soils

• Buried a straw layer in the soil significantly increased soil water in the early growth period and decreased soil salinity during the sunflower growing and off season.
• Combined application of straw layer burial and plastic mulch performed better than either the individual use of straw layer or plastic mulch for controlling salt accumulation in the topsoil layer, and increasing sunflower yield.

Soil salinization is a major limitation to high crop yield in saline soils of the Hetao Irrigation District of Inner Mongolia, China. As such, people are forced to use better and more effective approaches to soil management due to scarcity of freshwater and the adverse effects of climate. A three-year field experiment was conducted to investigate the effects of buried straw layer and plastic film mulch on soil moisture, soil salinity and sunflower (Helianthus annuus L.) yield in saline soils. Four field management practices were designed: bare ground (BG), plastic mulch (PM), buried maize straw layer (12 t ha−1) at a depth of 40 cm (SL), and combined application of plastic mulch and straw layer burial (PM + SL). Soil water at the 0–40 cm layer was higher under SL and PM + SL than under BG and PM within 45 days after sowing (DAS) but the reverse occurred thereafter. Compared to PM and BG, both SL and PM + SL significantly decreased the salt content of the upper 40 cm depth at sowing. Furthermore, PM + SL invariably decreased the salt content throughout the growth period of sunflower. In contrast, SL and PM moderately increased the salt content during the later growth period. Compared with BG, SL significantly decreased salt accumulation in the off season. Over the three years, the highest seed and biomass yield, 100-seed weight and head diameters of sunflower were obtained from the PM + SL plots. The average seed yield (3198 kg ha−1) under PM + SL exceeded the yields under BG, PM and SL by 51.9, 5.9 and 35.7% respectively. Therefore, PM + SL may be an efficient practice for reducing soil salinity and increasing sunflower yield in the Hetao Irrigation District and other similar ecological areas.