Deteriorating ground water quality used for irrigating grape

Samples of water used for irrigating grapes in Maharashtra and adjoining areas were collected from 112 bore wells in 1980–1981 and 1742 bore wells in 1993–2004 covering Nasik, Pune, Sangli, Solapur, Latur, Osmanabad, Satara; Ahmednagar; Buldhana and Bijapur (Karnataka) and Ratlam (M.P.) districts. Salinity in ground water ranged from 0.15 to 1.96 dSm⁻¹ (mean 0.84 dSm⁻¹) during 1980–1981. It ranged from 0.09 to 15.40 dSm⁻¹ (mean 1.11 dSm⁻¹) during 1999–2004. Out of 1742 samples tested, 852 were found with EC less than 1.0 dSm⁻¹, which is safe for growth and productivity of grapevines; 536 were within EC range of 1.0 to 2.0 dSm⁻¹, where growth is restricted due to salinity; 310 with EC more than 2.0 dSm⁻¹, where rootstock is necessary, and 44 were found with EC more than 4.0 dSm⁻¹, the situation, where even the tolerance limit of most commonly used rootstock is a failure. In initial study during 1980 and 1981, eightly samples were non-saline [EC < 1.0 dSm⁻¹]. Only 31 samples had EC more than 1.0 dSm⁻¹ and no sample exceeded EC 2.0 dSm⁻¹. Most of the irrigation waters were alkaline in nature and pH ranged from 7.31 to 8.91 during 1980–1981, and 5.05 to 3.72 during 1999–2004. However, during 1999–2004, 788 (45%) samples were not safe and need rootstock to tolerate high concentration of chlorides and 80 samples were very high in chlorides (>18 mel⁻¹) and even tolerance limit of most commonly used rootstock has been exceeded for grapes to obtain economic yield and good quality produce. Indiscriminate use of chemical fertilizers containing N appears to have contributed towards high NO₃-N in ground water.