Subsurface plastic film mulching: An innovative way to crop rain-fed wheat in lowland saline region

Background/Question/Methods There are large amount of lowland saline regions on our world. Crop production of these area is usually restricted by both soil salinity and water stress due to the lack of fresh water and irrigation, i.e. rain-fed. The Bohai Lowland Plain, located in North China, is a coastal area, and winter wheat (Triticum aestivum L.) is one of the most important crops in this area. Winter wheat is sensitive to salinity in its early growth and development, especially during the emergence and early seedling stages. Therefore, it also faces the dual challenges of salinity and drought in saline soils. Soil-surface plastic film mulching has been an important agricultural technique. In recent years, sub-surface plastic film mulching has been used widely in northwestern China to reduce soil evaporation and maximize rain-fed wheat production. A two-year field experiment was conducted in north China’s Bohai Lowland Plain to evaluate the effects of sub-soil plastic film mulching. We aim to determine the effects of sub-surface plastic film mulch on soil moisture and salinity dynamics as well as on winter wheat growth and yield under different soil salinities. Our results can be extrapolated to other semi-arid regions that are severely affected by drought and soil salinity.

Results/Conclusions Our results showed that subsurface mulching is an effective approach ameliorating water deficit and salt stress. Subsurface mulching significantly increased soil moisture in the top 20 cm of soil up to 33.1% at the seedling stage and decreased salinity by up to 73.7% in topsoil, compared with no mulch treatment. Subsurface mulching also reduced evaporation by 23.6 mm and increased transpiration by 14.6 mm. Plants in the mulch treatment showed higher aboveground biomass than those in the control group and had a similar harvest index. The average grain yield for the two years was 1579, 1743, and 2377 kg ha-1 greater under mulching under salinity levels of 1‰, 2‰, and 3‰, respectively, and the corresponding values of water use efficiency for yield were 27.6%, 40.4%, and 96.6%. Sub-soil plastic film mulching significantly inhibited soil surface evaporation and salt accumulation, promoted aboveground biomass, and increased grain yield and water use efficiency in dryland saline soil. Furthermore, the higher the soil salinity level, the more mulching suppressed soil salinity and improved water utilization by crops.