Influence of plastic film mulch on maize water use efficiency in the Loess Plateau of China

Abstract

Water is the main limiting factor for crop growth in dryland farming areas. Plastic film mulch (PM) is widely used to improve water use efficiency (WUE) and increase crop yield over conventional methods (no mulch, NM) in China. To get a better understanding about PM influence on water use process in the field, we defined WUETWI as the ratio of yield (Y) to the total water input (TWI), and divided WUETWI into 4 steps by means of a systematic and quantitative approach. The 4 steps included ratio of available soil water (SW) to TWI (SW0+P, where SW0 is available soil water at the sowing, P is seasonal precipitation), ratio of crop evapotranspiration (ETC) to SW, ratio of crop transpiration (T) to ETC and transpiration efficiency (WUET, Y/T). Three field experiments were conducted to analyze the influence of PM on soil moisture content, water consumption, and the grain yield of dryland spring maize (Zea mays L.). Results showed that, compared with NM, spring maize yield of PM was increased by 28.6%, and the WUETWI of PM was increased by 26.4% on average in the experiment 1. Since ETc with PM was slightly higher than that with NM, the ETC/SW was increased by 3.9%. In the experiment 2, the T/ETC with PM was 77.7% on average, 30.6% higher than that with NM; the Y/T increased by 13.6% from NM to PM. Precipitation storage efficiency increased linearly with the percentage of PM. Improved crop growth under PM led to higher crop biomass and higher leaf area index, which might result in higher transpiration rate. The T/ETC under PM was also increased.