TREATED EFFLUENT AND SALINE WATER IRRIGATION INFLUENCES SOIL PROPERTIES, YIELD, WATER PRODUCTIVITY AND SODIUM CONTENT OF SNOW PEAS AND CELERY

Abstract

To determine the effects of irrigation water quality, plants were irrigated with normal potable water [0.25 dS m−1 electrical conductivity (EC), 25 mg L−1 sodium (Na), 55 mg L−1 chloride (Cl)], treated effluent (0.94 dS m−1 EC, 122 mg L−1 Na, 143 mg L−1 Cl) and saline water with low salinity (1.24 dS m−1 EC, 144 mg L−1 Na and 358 mg L−1 Cl) and high salinity (2.19 dS m−1 EC, 264 mg L −1Na and 662 mg L−1 Cl) for snow peas, and high salinity (3.07 dS m−1 EC, 383 mg L−1 Na and 965 mg L−1 Cl) and very high salinity (5.83 dS m−1 EC, 741 mg L−1 Na and 1876 mg L−1 Cl) for celery. The greater salts build up in the soil and ion toxicity (Cl and Na) with saline water irrigation contributed to significantly greater reduction in root and shoot biomass, water use, yield and water productivity (yield kg kL−1 of water used) of snow peas and celery compared with treated effluent and potable water irrigation. There was 8%, 56% and 74% reduction in celery yield respectively with treated effluent, high salinity and very high salinity saline water irrigation compared with potable water irrigation. The Na concentration in snow peas shoots increased by 54%, 234% and 501% with treated effluent, low and high salinity saline water irrigation. Similarly, the increases in Na concentration in celery shoots were 19%, 35% and 82%. The treated effluent irrigation also resulted in a significant increase in soil EC, nitrogen (N) and phosphorus (P) content compared with potable water irrigation. The heavy metals besides salts build up appears to have contributed to yield reductions with treated effluent irrigation. The study reveals strong implications for the use of saline water and treated effluent for irrigation of snow peas and celery. The salt build up within the root zone and soil environment would be critical in the long-run with the use of saline water and treated effluent for irrigation of crops. To minimize the salinity level in rhizosphere, an alternate irrigation of potable water with treated effluent or low salinity level water may be better option.