Comparison of maize water consumption at different scales between mulched and non-mulched croplands

Plastic mulch can significantly improve soil water and temperature conditions in croplands, altering ecohydrological processes in agroecosystems. Therefore, analysis of maize water consumption in response to plastic mulch is of importance to agricultural water management. A field experiment was conducted in non-mulched (CK) and mulched (PM) maize fields of eastern Loess Plateau to monitor maize evapotranspiration at different scales. Portable photosynthesis system, sap flow system and eddy covariance systems were utilized to measure transpiration rate at leaf scale, sap flow at plant scale and evapotranspiration (ET) at field scale, respectively. The results indicated PM provided a wetter condition (+2.8% and +4.2% in soil water content for two growing seasons respectively) for maize, leading to higher leaf area index, plant height and aboveground biomass under PM treatment. PM increased leaf transpiration by 9.8%(similar to)33.3% and sap flow by 1.4%(similar to)-34.5% under different weather conditions. However, seasonal ET and the ratio of soil evaporation to ET decreased from 326.3(similar to)341.1 mm and 39.9%(similar to)42.8% under CK to 305.0(similar to)313.9 mm and 23.8%(similar to)34.9% under PM respectively, indicating PM declined seasonal ET and altered ET components, as evaporation decreased while crop transpiration increased. Thus, more water was used for maize growth, finally resulted in significantly higher yield and water use efficiency (p < 0.05). Our results shed light on how plastic mulch saves water and improves water use efficiency, which can provide important information for crop production modeling, water balance evaluation and sustainable management of dryland farming in this area.