Subsurface irrigation with ceramic emitters improves the yield of wolfberry in saline soils by maintaining a stable low-salt environment in root zone

The high salt concentration in soils depresses crop growth and saline soil reclamation. An appropriate irrigation method is essential to alleviate water shortage and promote wolfberry (Lycium barbarum L.) cultivation in saline soils. Subsurface irrigation with ceramic emitters (SICE) is a novel technique that maintains a stable soil water environment through adaptive outflow and holds a beneficial impact on saving water and increasing yield. However, the effect of SICE on salt leaching remains to be investigated. A field experiment was executed to investigate the salt leaching process in SICE and subsurface drip irrigation (SDI) in saline soils and their effect on wolfberry yield. HYDRUS-2D was calibrated and validated using experimental data to investigate the spatial -temporal variation of soil salinity. Subsequently, the salt leaching efficiency with different emitter discharges (0.10, 0.15, 0.24, and 0.33 L h-1) was assessed via HYDRUS-2D. Results indicated that SICE leached soil salt below the stress threshold after 50 days of irrigation, while SDI required 148 days. At the end of irrigation, SICE formed a low-salt zone that occupied 74.14% of the main root zone, while the zone with SDI was 60.69%. Generally, SICE provided a stable low-salt environment for wolfberry root system for 117.5 days (69.9% duration of growth period). SICE improved the wolfberry yield and root-zone soil desalination efficiency (DE) by 0.17 t ha-1 and 0.41% cm-1 than SDI, respectively. When emitter discharge increased to 0.24 L h-1, the root zone of wolfberry was protected from salt stress, but DE decreased gradually. SICE with an emitter discharge of 0.24 L h-1 was recommended for wolfberry in saline soils of Ningxia. The results reveal that SICE is an efficient salt leaching method for saline soil management and crop yield improvement.