STUDIES ON ZINC IN RICE-WHEAT GROWING SOILS IN SUBTROPICAL AREAS OF JAMMU REGION

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Date
2016
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Division of Soil Science and Agricultural Chemistry, Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu
Abstract
Available zinc (Zn) being an important micronutrient in the rice-wheat cropping system the study was carried out in Kathua, Samba and Jammu districts, to observe and understand the behavior of Zn in soil which included distribution, fractionation, Langmuir adsorption characteristics, critical limit of Zn for basmati rice (cv. Basmati 370) and the effect of Zn on some important biochemical properties (total sugar, starch and soluble protein) in basmati under the subtropical areas of Jammu. The soils were mildly acidic to neutral in reaction as pH values ranged 6.10-7.68 with a mean of 6.87. Soil organic carbon (OC) ranged from 3.20 to 7.80 with a mean of 5.92 g kg-1 and the average available N, P, K of the soils were 204.5-297.0, 4.8-10.9 and 61.2-109.25 kg ha-1. The DTPA extractable Zn was deficient in about 60% of the samples analyzed in all the three districts, the value of which ranged from 0.21 to 0.79 mg kg-1 mean of 0.56 mg kg-1. Most dominant texture pattern was clay loam. The order of Zn fractions was organically complexed (OCx) > amorphous sesquioxide bound (AMOX) > manganese oxide bound (MnOX) > insoluble ferrous iron bound (IFFe) > crystalline sesquioxide (CRYOX) > water soluble oxide bound (WSEX). The values ranged 1.2 -9.0, 1.4 - 9.74, 0.17 - 1.73, 0.0 - 1.80 and 0.11 - 0.52 with mean values of 3.91, 3.17, 0.91, 0.81 and 0.52 mg kg-1 respectively. The Langmuir adsorption maxima (a Max) and bonding energy (b) of the soils ranged between 0.43 to 1.21 and 2.67 to 32.52 with mean values of 0.69 mg kg-1 and 9.62 mg kg-1 respectively. Critical limit of available Zn in the basmati growing areas of Bishna and R.S.Pura were 0.60 and 0.56 mg kg-1 in soil and 14.4 and 18.2 mg kg-1 in basmati plant (cv B-370) respectively. The soluble protein, total sugar and starch varied from 5.62 – 8.37, 5.03 - 6.95 and 71.16 – 75.99 and the highest soluble protein and total sugar and starch (8.37, 6.95 and 75.99 percent, respectively) were recorded with treatment ZnSO4.7H2O@ 20 kg ha-1. DTPA extractable Zn was found deficient in the study area. All the fractions and Zn adsorbed were positively significantly correlated with OC and pH therefore; OC and pH should be maintained at optimum level for Zn availability in soils. The critical limit in the Bishna and R.S.Pura soils should be maintained at 0.60 and 0.56 mg kg-1, whereas in plant basmati rice (cv B-370), it should be maintained at 14.4 and 18.2 mg kg-1, respectively. For starch, soluble protein and total sugar analysis in basmati rice Zn availability must be maintained at optimum level. Grain yield and dry matter yield of basmati rice increased with the increases in Zn supply.
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