Effect of whole filed plastic mulching with bunch planting on soil thermal-moisture characteristics and winter wheat yield in the lowland plain of Hebei Province

The objective of this study was to clarify soil water, soil salinity, soil thermal characteristics and yield of winter wheat in Hebei Lowland Plain under total soil-plastic mulching with soil covering and bunch planting. The study was carried out at Nanpi Eco-agricultural Experimental Station of Chinese Academy of Sciences in 2014–2015. Two treatments included the treatment of plastic film mulching the entire soil surface with bunch planting (PM) and the treatment of rotary tillage with traditional seed planting as the control (CK). Soil moisture content, soil salinity, soil temperature and heat flux was monitored from winter wheat seedling emergency to harvest. Winter wheat yield plus yield components were analyzed too. The results showed that PM improved soil moisture in the topsoil during wintering and re-greening stages. Although soil water content was higher by 16.4% under PM treatment than the CK treatment (P < 0.05), plastic mulching restricted precipitation water supply by up to 10% after re-greening. PM improved soil temperature of the 10 cm deep soil, with average soil temperature increment of 3.8% for the entire growing season (P > 0.05). Also PM reduced diurnal range of soil temperature by 0.5 ℃, compared with CK. PM favored the absorption and storage of heat energy, with 14.8 Wm2 more soil heat flux in PM than in CK during the whole growth period. The mean daily soil heat flux under PM increased by several folds over that under CK during daytime, which showed that PM increased downward flow of heat energy. The changes in temperature and heat flux showed that the total plastic mulching enhanced soil ability to resist ambient temperature changes. Electrical conductivity in the topsoil was significantly (P < 0.05) lower by 24.2% under PM than under CK during the whole growing season. It showed that PM generally restrained salt accumulation at surface soil. PM increased kernels per spike and 1000-kernel weight of winter wheat compared with CK. The yield of winter wheat increased by 10.4% under PM compared with that of CK (P > 0.05). This study provided theoretical and technical support for the application of total plastic mulching in winter wheat fields in coastal plains of Bohai Sea.