CHARACTERIZATION OF SALT AFFECTED SOILS AND YIELD OF CROPS GROWN IN SRIKALAHASTHI DIVISION OF CHITTOOR DISTRICT OF ANDHRA PRADESH

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Date
2017
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Acharya N.G. Ranga Agricultural University
Abstract
The present investigation was carried out to characterize the salt affected soils in Srikalahasthi division of Chittoor district of Andhra Pradesh. For this purpose, 152 surface soil samples and irrigation water samples were collected from five mandals of Srikalahasthi division viz., Srikalahasthi, Yerpedu, B.N.Kandriga, Thotembedu and K.V.B.Puram. Soil samples were analyzed for physical, physico-chemical and chemical properties and irrigation water analyzed for its quality. Per cent clay, silt and sand content ranged from 6.92 to 62.57, 2.28 to 28.95 and 30.31 to 85.08, respectively. The study area was dominated by medium textured soils (71.05 per cent) followed by coarse textured (18.43 per cent) and fine textured soils(10.42 per cent). Out of 152 soil samples collected from the study area 81 (53.28 per cent) soil samples were found to be strongly alkaline, while 47 (30.92 per cent) and 24 (15.78 per cent) soil samples were found to be mildly and moderately alkaline in reaction, respectively. Out of 152 soil samples collected from the study area, 61 (40.13 per cent), 57 (37.5 per cent), 21 (13.81 per cent), 9 (5.92 per cent) and 4 (2.63 per cent) were non saline, slightly saline, moderately saline, strongly saline and very strongly saline, respectively. The organic carbon status of 78.29 per cent of soil samples was low. Majority of soils in the study area were moderately calcareous (69.73 per cent) followed by strongly calcareous (17.10 per cent) whereas 13.16 per cent soil samples were said to be non calcareous. CEC of soils varied from 30.92 to 72.52 cmol(p+ )kg-1 with a mean value of 50.53 cmol(p+ )kg-1 . Per cent base saturation of soils ranged from 59.17 to 99.36 with a mean value of 70.11. The ESP > 15 was noticed in 59.86 per cent soil samples. Soils of Srikalahasthi division were deficient in available nitrogen (87.5 per cent). Out of 152 soil samples studied for available phosphorous, 36, 54 and 62 soil samples were low, medium and high, respectively. The status of potassium in 18, 81 and 53 soil samples were high, medium and low respectively. 77.63 per cent of soil samples showed sufficient in available sulphur content while only 22.37 per cent soil samples showed deficient in available sulphur content. The exchangeable cations of soils of Srikalahasthi division were found in the order of Ca2+> Na+ > Mg 2+> K+ . But the soluble cations of the saturation extract was in the order of Na+ >Ca2+>Mg2+>K+ . In the saturation extract of the soils, chloride was the dominant anion followed by sulphates, bicarbonates and carbonates indicating chloride-sulphate type of soil salinity. Among the 152 soil samples collected from Srikalahasthi division, 65.14 per cent samples have SAR <13 and the remaining 34.86 soil samples have SAR>13. The cationic composition of irrigation water in the study area was found in the order of Na+ >Mg2+>Ca2+>K+ whereas the order of anions in irrigation water was Cl- >SO4 2- >HCO3 - >CO3 2- .The study revealed that 46.05 per cent of irrigation water samples were alkaline in reaction and most of the water samples (69.79 per cent) showed high salinity (C3) followed by very high salinity (C4-28.97 per cent) and medium salinity (C2-1.32 per cent). The SAR of water samples were found in the order of S1>S2>S3 class respectively. Based on RSC, majority of water samples were safe (67.11 per cent) followed by moderately safe (15.79 per cent) and unsafe (17.10 per cent).Based on Mg: Ca ratio, 8.55 per cent of irrigation water samples were classified as unsafe for irrigation. As per the guidelines of central soil salinity research institute, 69 samples (45.39 per cent), 17 samples (11.18 per cent), 9 samples (5.92 per cent) and one sample were found to be good, marginally saline, highly alkali and high SAR saline, respectively. Remaining 56 irrigation water samples were classified as medium to high salinity, medium to high sodium water, medium to very high alkalinity as per salinity, SAR and RSC classes established by Gupta (1979). Out of 152 soil samples 93 soil samples identified as salt affected soils based on pHs, ECe and ESP, of this 5 (3.28 per cent), 58 (31.15 per cent) and 30 (19.73 per cent) soil samples were classified as saline, sodic, saline-sodic respectively. Remaining 59 soil samples were found to be normal. The soil related constraints studied in the salt affected soils and majority of normal soils of Srikalahasthi division were alkalinity, high soluble salt content, moderately to strongly calcareous, low in status of organic carbon, low in available N, P, K and deficient in available sulphur. Paddy yield of salt affected soils viz., sodic, saline-sodic and saline ranged from 3062 to 4250 kg ha-1 with a mean value of 3544 kg ha-1 whereas yield of paddy in normal soils ranged from 5062 to 6200 kg ha-1 with a mean value of 5496 kgha-1 . Yield of salt affected soils was less as compared to normal soils in the study area. Salt affected soils and irrigation water quality can be managed by adopting effective reclamation measures by the farmers’ so as to improve the health of the soils and quality of irrigation water and ultimately the growth and yield of crops can be improved.
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D5530
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