Effect of Mulched Drip Irrigation with Brackish Saline Water on Soil Water Repellency Characteristics of Saline-Alkali Field

Abstract

A two-year field experiment was conducted to investigate soil electric conductivity (EC1:5), soil pH value, and soil water repellency (SWR) in response to mulching method (M1: fully mulched, M2: partially mulched) and dripped irrigation frequency with brackish saline water in the Hetao Irrigation District under arid growing conditions. SWR was assessed by using the water drop penetration time (WDPT) method, and soil-water repellency characteristic curves (SWRCC) were built. Results demonstrated that SWR and EC1:5 showed a significant positive correlation in mulched drip irrigated saline-alkali field; while it was not so obvious between SWR and soil pH value. Under the experiment condition with weak alkaline and brackish irrigation water, WDPTs of the soil near drip emitters were decreased on the 7th day after each drip irrigation at low irrigation frequency; whereas, WDPTs of the soil away from drip emitters were increased on the 7th day after a single irrigation. WDPTs were overall decreased after high frequency irrigation (once every three days). SWRCC in mulched drip irrigated saline-alkali soil can be well fitted by Gaussian and Lorentzian equations. The SWRCC curves showed that drip irrigation showed no effect (P<0.05) on θm (the volumetric soil moisture when WDPT was maximum), whereas significantly changed θc (the volumetric soil moisture when WDPT was less than 5 s). Lorentzian equations showed better performance for SWRCC regression than Gaussian equations, and θm and θc can be obtained from Lorentzian curve. The research result can provide assistance for utilization of drip irrigation with brackish saline water and water repellent soil.