Soil water utilization with plastic mulching for a winter wheat-summer maize rotation system on the Loess Plateau of China

The sustainability of soil water is a primary factor for the sustainable development of dryland farming. This study was aimed to (1) investigate the characteristics of crop evapotranspiration (ET) and (2) assess the sustainability of soil water utilization under the continuous plastic mulching practices in the winter wheat-summer maize crop rotation system on the Chinese Loess Plateau. A continuous experiment of rain-fed field mulched by transparent (TF) and black (BF) plastic film was implemented for three years. The results shown that compared with the non-mulched treatment, the TF and BF treatments annually consumed more soil water with 20.8 and 16.3 mm during wheat growing season, respectively, but they could annually save 34.5 and 20.9 mm soil water during maize growing season, respectively. The ET during the wheat growing season remained dominant within the 0-100 cm soil depth, while the maize plants would exploit the deeper soil water in the subsoil (100-200 cm) during its growing season. Accordingly, the mulched treatments during the maize growing season could store more soil water in the 0-100 cm soil depth, which can provide effective soil moisture for the next wheat season. Although the plastic mulching practices insignificantly changed the total crop ET with a small quantity compared with the non-mulched treatment, they tended to reduce non-productive soil evaporation and increase productive plant transpiration. Attributable to expected crop ET characteristic difference under plastic mulching treatments, the continuous plastic mulching significantly increased the crop grain yields and water use efficiency, which could greatly contribute to the sustainability of local dryland farming in a winter wheat-summer maize rotation system.