Reclamation of heavy coastal silt saline soil and optimal tomato production through a drip irrigation system with saline water

Purpose It has always been challenged to improve heavy coastal silt saline soil for crop productions through establishing an irrigation system with saline water. This study was aimed to investigate the effect of the electricity conductivity of irrigation water (EC w ) on soil salinity (EC e ), sodium adsorption ratio (SAR) and pH of the saturated paste (pH s ), tomato yield, and irrigation water use efficiency (IWUE). Methods A two-year field experiment of five EC w treatments (0.7, 3.2, 4.7, 6.2, and 7.8 dS m −1 , respectively) was conducted under ridge tillage in the Bohai Rim region, China through a drip irrigation system. Results A linear correlation between EC w and soil desalinization rate (SDR) and between the irrigated water amount and SDR was revealed and the final average EC e , SAR and pH s readings at 1 m deep soil (40.2 dS m −1 , 56.2 (mmol L −1 ) 0.5 , and 7.82, respectively) dropped to those within the main root zone with each of five treatments (21.3–26.6 dS m −1 , to 32.4–37.1 (mmol L −1 ) 0.5 and 7.16–7.75, respectively), indicating an outstanding soil reclamation. The tomato survival rate was over 90% when the EC w was kept below 7.8 dS m −1 , while growth and yield of tomato and IWUE were generally unaffected as the EC w was below 4.7 dS m −1 . Conclusion The EC w of dripping water should be maintained below 3.9 dS m −1 and the soil matrix potential be controlled above -5 kPa at 20 cm deep soil beneath dripping emitters for a high-yield tomato cultivation in the heavy coastal silt saline lands.