Dynamics of Water Quality and Deficit Irrigation on Residual Soil Micronutrients, Carbon Sequestration and Crop Productivity in a Greenhouse Environment

Abstract

The effects of different irrigation level and water quality on residual soil micronutrients, pH, carbon sequestration and crop productivity in a greenhouse setting for sustainability of tomatoes (Solanum lycopersicum cv. Ezmir) production were examined. Groundwater as a traditional source of irrigation and, recycled wastewater as an alternative source were applied via drip irrigation with design frequency two days. Three water deficit level maintaining soil moisture content at 80%, 70% and 60% field capacity compared to full irrigation based on crop water requirements were designed. Profile probe working on time-domain reflectometry principle was used to measure in-situ soil moisture content inside root-zone. The study found that residual micronutrients in the control and 80% FC treatment were statistically similar despite of water quality and was highest in recycled wastewater case. Also, both the carbon sequestration by soil-plant system and soil pH in the 80% FC treatment were not found to be significantly different to full irrigation, postulating that considerable amount of total organic carbon could be sequestered through deficit irrigation strategy along with saving of water and nutrients. Crop productivity of greenhouse tomatoes was adversely affected in water stress scenarios. Based on findings, it is recommended that the recycled wastewater as a source water quality designed at 80% FC level is most appropriate deficit irrigation strategy to save nutrients and conserve soil-carbon.