Domestic Greywater Irrigation on Soil Properties and Enzymatic Activities

A field investigation was undertaken during the Rabi season of 2019-20 in a selected farmer's field at Yelavatti village, near Shivamogga City, Karnataka, India to evaluate the effect of domestic greywater irrigation on soil properties and enzymatic activity.  Four types of irrigation water were used for this investigation: greywater, treated greywater, structured greywater, and bore well water (as a control). The results revealed that treatments that received irrigation with domestic greywater significantly improved soil reaction (pH), electrical conductivity (EC), soil organic carbon (SOC), and soil available nutrient status at all growth stages of the Okra vegetable grown soil. The plots which received domestic greywater irrigation alone recorded significantly higher soil organic carbon with 5.92 g/kg, 6.67 g/kg, 6.57 g/kg, available nitrogen with 240.58kg/ha, 281.29 kg/ha, 325.29 kg/ha, available phosphorous with 78.15 kg/ha, 89.54kg/ha, 105.67 kg/ha and available potassium with 317.56 kg/ha, 421.84 kg/ha and 449.53 kg/ha at 30DAS, 60DAS and 90DAS respectively. Domestic greywater irrigation alone treatment recorded significantly higher dehydrogenase activities with 28.72µg TPF g-1 of soil day-1. 32.59 µg TPF g-1 of soil day-1, 35.87 µg TPF g-1 of soil day-1, phosphatase activity with 31.73 PNP g-1 soil hr-1, 35.89 PNP g-1 soil hr-1, 39.47 PNP g-1 soil hr-1 and urease activities with 321.39,355.61 and 359.07 µg NH4+ g-1 soil hr-1 at 30 DAS, 60 DAS, and 90 DAS respectively. A similar trend of results was also observed in exchangeable Ca, Mg, and available S as well as DTPA-extracted Zn, Cu, Mn, and Fe in the soil at all growth stages. Irrigation with bore well water alone recorded significantly lower levels of soil pH, EC, SOC, soil available nutrients status, and enzyme activities at all stages of the crop growth. Safe with minimum treatment in the use of domestic greywater irrigation is the best option to mitigate the water crises in future days agriculture.