Water Requirements of Drip-Irrigated Maize (Zea mays L.) with Plastic Mulching in Heilongjiang, Northeast China

Abstract

Abstract. A large area of rainfed maize ( L.) is planned to be replaced by maize under drip irrigation with plastic mulching (MDI) in Heilongjiang, northeast China, through a “water-saving and grain-increasing action” project. However, knowledge is lacking on the water requirements of maize under MDI. On the basis of a locally developed crop coefficient for a site, the spatial and temporal variations in crop water requirement (ETc) and net irrigation requirement (Nir) of maize under MDI in Heilongjiang were evaluated. The average ETc and Nir of maize under MDI in the period from 1960 to 2017 for 29 meteorological stations were 279 to 388 mm and 73 to 198 mm, respectively, which are approximately 10% and 15% lower than the ETc and Nir under conventional surface irrigation (NSI). The differences in ETc and Nir between the two irrigation technologies are significant in the southwestern region, which demonstrates that the intensive planning of MDI in the southwest is justified. The gross irrigation requirement of maize under MDI in an excessive drought year is estimated as 437 million m3 for the project, which is 137 million m3 less than the irrigation requirement using NSI.HighlightsAverage ETc and Nir of maize under MDI are approximately 10% and 15% lower than those under NSI.The differences in ETc and Nir are significant in the southwestern region of Heilongjiang.The estimated gross irrigation requirement of maize under MDI is much less than that under NSI. Keywords: Crop coefficient, Drip irrigation, Maize, Northeastern China, Plastic mulch, Water requirement.