Use of low quality groundwater for reclamation of saline-sodic soil by growing rice and wheat crops

A field experiment was conducted at Qaim Bharwana, district Jhang, Pakistan on a saline-sodic soil (ECe = 12.7-20.1 dS m/sup -1/, pHs 10.3-10.4, SAR = 157.0-273.9 at 0-15 cm soil depth and ECe = 5.4-12.1 dS m/sup -1/, pHs = 9.5-10.0, SAR = 70.1-171.4 at 15-30 cm soil depth) following rice-wheat rotation using tube well water (EC = 1.32 dS m/sup -1/, SAR = 4.8, RSC = Nil, Ca:Mg = 0.74) for irrigation. The treatments tested were: TW) Tube well water alone, FYM-20) FYM at the rate of 20 Mg ha/sup -1/, Gyp-100) gypsum at the rate of 100% soil gypsum requirement (SGR) and FYM+Gyp) FYM at the rate of 10 Mg ha/sup -1/ gypsum at the rate of 50% SGR. After rice 2005 harvest, soil analysis showed that pHs for both the soil depths decreased non-significantly, per cent decrease over initial being maximum with Gyp-100 followed by FYM + Gyp, TW and FYM-20 at 0-15 cm, while treatment effectiveness order for pH (per cent) decrease was FYM + Gyp>TW>FYM-20 at 15-30 cm soil depth but slightly increased with Gyp-100. The ECe decreased non-significantly with treatments, per cent decrease over initial being maximum with FYM+Gyp followed by Gyp-100, FYM-20 and TW at 0-15 cm. Decrease in pHs was significant at 15-30 cm soil depth and the treatment order was FYM+Gyp>TW>Gyp-100>FYM-20. Treatments differed non-significantly to lower SAR for both the soil depths, per cent decrease being maximum with FYM+Gyp followed by Gyp-100, FYM-20 and TW at 0-15 cm, while the order was FYM+Gyp>Gyp-100>FYM-20>TW at 15-30 cm soil depth. Soil analysis after harvest of wheat 2005-06 depicted a decrease in pHs with all the treatments, order being Gyp-100>FYM + Gyp>FYM-20>TW at 0-15 cm soil depth. At 15-30 cm depth, the treatment order to decrease pHs was Gyp-100>FYM+Gyp>TW>FYM-20. Maximum decrease in ECe was observed with FYM+Gyp followed by TW, FYM-20 and Gyp-100 at both the 0-15 cm and 15-30 cm soil depths. Maximum reduction in soil SAR was observed with FYM+Gyp followed by Gyp-100, FYM-20 and TW at both the soil depths. The paddy yield of rice 2005 was maximum with FYM+Gyp followed by Gyp-100, FYM-20 and TW. The highest grain yield of wheat during 2005-06 was obtained with FYM+Gyp followed by FYM-20, Gyp-100 and TW. Maximum net profit was obtained with FYM + Gyp followed by FYM-20, Gyp-100 and TW. (author)