Effects of partial root-zone drying irrigation and water quality on soil physical and chemical properties

Using recycled wastewater (RW) is considered to be a strategic choice for overcoming water scarcity worldwide, so there is a pressing need to improve irrigation and nutrient uptake to sustain crop yields and at the same time to reduce the negative impacts of RW. In the present study, tomato plants (Lycopersicon esculentum Mill. var. “Azmier”) were exposed to three different water qualities: recycled wastewater (RW); fresh municipal tap water (FW); and a blend of RW and stormwater (BW), in combination with five irrigation scenarios: full irrigation (FI) full plant water requirement; deficit irrigation (DI), with 75% and 50% of FI as DI75 and DI50, respectively; and partial root-zone drying (PRD), with 75% and 50% as PRD75 and PRD50, respectively. The effects of these treatments on soil hydraulic conductivity (Ks), soil pH, root growth, leaf area (LA) as well as the residual phosphorus (P), potassium (K+), calcium (Ca2+) and magnesium (Mg2+) in the soil were investigated. The results showed that there was no significant difference in the soil Ks. However, different types of irrigation waters significantly affected the soil pH, while irrigation scenarios had no effect on soil pH. Also, irrigation scenarios influenced root growth and LA, while PRD scenarios lowered soil P, K+, and Mg2+ concentration compared to DI. The results also showed that water quality influenced canopy coverage 107days after planting (DAP). It is clear that PRD is a promising scenario for sustaining agriculture in areas with high water scarcity.