Evaluation of soil chemical properties irrigated with recycled wastewater under partial root-zone drying irrigation for sustainable tomato production

Recycling of wastewater is becoming more popular in order to augment the inadequate irrigation supplies and meet the growing water demands for agriculture in arid regions of the world. This study investigated the environmental impact of deficit irrigation regimes on soil properties with five scenarios using recycled wastewater (RW), fresh tap water (FW), and a blend of RW and stormwater (BW). The five irrigation scenarios were applied to tomato plants growing in pots and included: (i) full irrigation (FI); (ii) partial root zone drying (PRD) irrigation at 75% of FI involving irrigation of only one part of the root zone, while the other part was exposed alternately to soil drying (PRD 75); (iii) PRD irrigation at 50% of FI (PRD 50); (iv) conventional deficit irrigation (DI) at 75% of FI applied on both sides of the root zone (DI 75); and (v) DI at 50% of FI (DI 50). Among the different irrigation scenarios, the PRD 75 treatment led to the lowest level of salinity for the surface soil layer. The PRD reduced TN in the soil compared with DI, while the water source significantly increased soil TN and TC with RW by 4% and 7%, respectively, compared with FW under FI. However, the irrigation scenarios and water sources did not show significant differences in the sodium absorption ratio (SAR), but PRD could reduce SAR compared with DI when using water with a high sodium concentration, such as RW.