Effects of subsurface pipe drainage on soil salinity in saline‐sodic soil under mulched drip irrigation

Abstract The increasing prevalence of alkali‐saline soil is a major challenge to the sustainable development of agriculture. In this study, a subsurface pipe drainage experiment using different pipe spacing (10, 15, 20 and 25 m) was conducted to reduce soil salinity. The results indicated that the salt content of the 0–80 cm soil layer decreased from 35 to 15 g kg‾¹ after being treated with subsurface pipe drainage. In contrast, the control treatment of ditch drainage had a limited effect on decreasing the soil salinity, the salt content remaining at 25–35 g kg‾¹. In total, 2030 m 3 water and 280 t salt were drained during the experiment. Of the subsurface drainage pipe treatments (i.e. spacing at 10, 15, 20 and 25 m) 365, 672, 514 and 479 m 3 water were drained, respectively, as well as 66.4, 102, 59.2 and 52.3 t salt, respectively. In addition, the average drainage rate achieved by subsurface drainage pipes was 1.64 m 3 h‾¹ and the salt leaching intensity was 46.3 t hm‾ 2 . The optimal pipe spacing for reducing soil salinity was 15 m, with an effective desalination rate reaching 65.8%. At this spacing, the average drainage rate was 2.87 m 3 h‾¹ and the salt leaching intensity was 150 t hm‾ 2 . Moreover, the survival rate of cotton at 15 m spacing exceeded 60%. © 2019 John Wiley & Sons, Ltd.