EFFECTS OF WATER STRESS AND QUALITY ON RESIDUAL SOIL MACRONUTRIENTS AND ROOT-ZONE SALINITY FOR TOMATO PRODUCTION IN A PROTECTED CROPPING ENVIRONMENT

Abstract

Improvement of water productivity from irrigated tomatoes while maintaining yield and soil health is a global challenge. This study aimed to examine the effect of varying water quality and water stress (deficit irrigation) scenario on different soil parameters of tomatoes in a greenhouse setting to establish an optimum soil-water-plant environment for sustainable production. The study was completed by simulating tomato growing conditions in the Northern Adelaide Plains of South Australia in two consecutive years (2017-2018 and 2018-2019). Three water sources selected as varying water quality were: groundwater, recycled wastewater and mixed of both. Water was applied via drip irrigation system in four irrigation scenarios maintaining irrigation frequency of two days. The results showed that irrigation with recycled wastewater had the highest residual nutrients accumulated in soil after completion of a crop growth season. The study also indicated that the residual soil macronutrients in the 80% FC treatment were not significantly different to that of the 100% FC regardless of water quality. The results thus suggested that a considerable amount of water and fertilizer can be saved through application of DI technique - especially at 80% FC level without having a significant difference of soil macronutrient compared to full irrigation. This study also found that salt accumulation in the effective root-zone was affected by both water quality and irrigation scenarios and was highest in the case of recycled wastewater.