EFFECT OF PLASTIC MULCHING ON WATER BALANCE AND YIELD OF DRYLAND MAIZE IN THE LOESS PLATEAU

Less and varied soil-water supply is the main limiting factor for crop production in the Loess Plateau of China. A field study on dryland spring maize was conducted to investigate the effects of plastic film mulching practice on maize growth, yield, water use efficiency (WUE), soil water storages (SWS) and the ratio of transpiration to evapotranspiration (T/ET) on the Changwu Tableland of the Loess Plateau in 2013. The T characteristics of maize were measured using the sap flow method. Results showed that plastic film mulching treatment had a seedling emergence rate of 98.1%, which was significantly higher than the 80.2% of the non-mulching treatment. Maize plants reached every growth stage earlier and the whole growth period was shortened by 14 days under plastic film mulching. Soil water storage was markedly higher in plastic mulching field than in non-mulching field before July. However, at reproductive stages soil water content within the 40-150 cm profile was lower under plastic film mulching because of relatively enhancement of root water absorption. The daily mean ET under plastic mulching was lower than that under non-mulching, whereas the daily mean T was the opposite. The T/ET of maize was 68.1% under non-mulching and 85.5% under plastic mulching from July to September. Under the same LAI, the T/ET of plastic mulcingh was greater than that under non-mulching conditions. The plastic mulching decreased ET but increased WUE by 89.8%. It was concluded that plastic mulching is beneficial for increasing available water and improving the yield of maize on the Loess Plateau.