Water Consumption Patterns and Crop Coefficient Models for Drip-Irrigated Maize (Zea mays L.) with Plastic Mulching in Northeastern China

Abstract

Abstract. Our investigations into the water consumption patterns of maize ( L.) grown using surface drip irrigation with and without plastic mulching were based on three consecutive years (2014-2016) of field experiments in a typical area of northeastern China. We evaluated seasonal crop evapotranspiration (ETc) and how it was partitioned into soil evaporation (Es) and plant transpiration (Tp) during the season. Development of crop coefficient (Kc) prediction models was based on the growth day (GD) and leaf area index (LAI) of the crop, as well as the growing degree-days of air (GDDair) and soil (GDDsoil). Results showed that plastic mulching significantly reduced Es by 41.6 to 53.5 mm (p < 0.05) compared to not mulching, while it increased Tp by 23.2 to 40.4 mm (p > 0.05) for spring-planted maize. While plastic mulching normally reduced ETc during the crop growth period, the change was not significant (p > 0.05). The three-year mean Kc for the maize growth period declined by 3.0% under plastic mulching. The mean Kc was lower for the plastic mulching treatment than for the non-mulching treatment in both the early and late season, while it was slightly higher at mid-season. The three-year means of mid-season Kc (Kc-mid) under plastic mulching and non-mulching were 1.06 and 1.05 lower, respectively, than the FAO-56 recommended value. In addition, the Kc estimation model based on GDDsoil achieved the best fitting accuracy. We recommend applying this GDDsoil model to mulched drip irrigation of maize in northeastern China to obtain more accurate Kc estimation for optimizing and developing mulched drip irrigation in this region. Keywords: Crop coefficient, Drip irrigation, Maize, Northeastern China, Plastic mulch.