LAUSR

Abstract Drip irrigation has been widely used in arid regions in recent years. However, how the drip irrigation technology can affect soil evaporation and crop transpiration, and whether it can save water under the sufficient irrigation condition, are still of great controversy in the world. In order to interpret the problem, we initially conducted the comparative experiments between the drip-irrigated maize field and the border-irrigated maize field in large areas during 2014−2018. Evapotranspiration (ET), soil evaporation (E) and crop transpiration (T) over the drip irrigation (DI) and border irrigation (BI) treatments were continuously measured by two eddy covariance systems, micro-lysimeters and the packaged stem sap flow gauges. Results indicate that the total maize ET over the whole crop season under the DI treatment was lower than that under the BI treatment by 4%, 16 %, 2%, 16 %, -3% in 2014, 2015, 2016, 2017 and 2018, respectively. For the whole five years, DI averagely decreased ET by 7% and 40 mm per year against the traditional BI. Compared to BI, DI reduced E by 0.1 % in 2014, 50 % in 2015, 7% in 2016, 22 % in 2017, 17 % in 2018 and 23 % (30 mm) in 2019 averagely, and shortened the growth days by 15, 23, 10, 5, and 13 days, respectively, for the whole five years. Our research uncovered the ET decrease of DI against BI was mainly due to the significant reduction in E and growth days. In addition, the acceleration of crop growth induced by DI is a new finding and will provide an important scientific basis for interpreting the magic power of the technology and extending it to more arid regions to solve the global water and food crisis.