Effects of film mulching on evapotranspiration, yield and water use efficiency of a maize field with drip irrigation in Northeastern China

Drip irrigation under film mulching is applied widely in maize field in northeastern China according to the “Water saving and grain increasing action” implemented by Chinese government in recent years. The influence of mulching on water consumption and grain yield still needs systematic investigation for a better evaluation of such managements. In this study, a field experiment was conducted for three consecutive years in northeastern China. Net radiation above canopy (Rn), soil evaporation (Es) and crop transpiration (Tr), crop growth and yield were measured in film mulching (M) and non-mulching (NM) maize fields with drip irrigation. The results showed that the total evapotranspiration (ET) of the M treatment was between 413.4-471.3 mm, which was 2.8-5.2% lower than those of the NM treatment (430.0-497.4 mm) for the three years. Film mulching reduced the Rn of the maize field, which is an important reason for the lower ET of the M treatment. The total Es of the M treatment was 45.2% lower, yet, the total Tr of the M treatment was 8.9% higher, than that of the NM treatment. The ratio of Es to ET was 12.5-14.5% of the M treatment, while the ratio of the NM treatment was as high as 21.7-25.2%. The measured basal crop coefficient during the mid-growth period (Kcb-mid(mea)) of the M treatment (0.96-1.17) was 3.6-9.9% higher than those of the NM treatment (0.89-1.13) for the 3 years. However, the mean evaporation coefficient (Ke) of the entire growth period of the M treatment (0.09-0.10) was significantly lower than those of the NM treatment (0.18-0.19). Consequently, the mean crop coefficient (Kc) of the M treatment was 3.2-5.5% lower than those of the NM treatment for the 3 years. The maturity stage was accelerated by 4-5 days in the field with the M treatment. The yield increased by 5.9-8.8% and the water use efficiency (WUE) increased by 10.7-13.1% in the field with the M treatment for the 3 years. Such results are helpful to explicit the influence of mulching on water consumption, and give important reference to develop precise irrigation scheduling in maize field in this area.