SOIL FERTILITY EVALUATION OF NAIRA VILLAGE, SRIKAKULAM DISTRICT WITH SPECIAL REFERENCE TO SULPHUR STATUS
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Date
2012
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ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY
Abstract
A project was under taken to evaluate the fertility status in soils of Naira
village, Srikakulam district with special reference to sulphur status. Hundred and
fourteen soil samples were collected in representative areas of the village by
using revenue map of Naira. The soil samples were analyzed for their physicochemical
properties and forms of sulphur. The inorganic sulphate sulphur was
extracted by different extractants viz. 0.15% calcium chloride, 0.5 M sodium
bicarbonate, 1 N ammonium acetate, 0.01 M mono calcium phosphate and
Morgan’s reagent. Correlation studies were also carried out among different
forms of sulphur and between soil properties. The results indicated that 34.2 per
cent were neutral, 10.5 per cent were slightly acidic, while the remaining 55.3 per
cent of the samples were moderately acidic to strongly acidic in soil reaction. All
the samples were non-saline. The soils were low in organic carbon and available
nitrogen, medium in available phosphorus and potassium. Exchangeable calcium,
magnesium and available sulphur, DTPA extractable manganese, iron and copper
were above critical limits, whereas zinc content was below critical limit in few
soils. The soils were non-calcareous in nature and low in cation exchange
capacity. Texturally they were loamy sand, sandy loam, sandy clay loam and
sandy clay showing wide variation in texture.
Among the different forms of sulphur, total sulphur was high followed by
organic sulphur, heat soluble sulphur, inorganic sulphur and adsorbed sulphur.
Organic sulphur contributed to more than 90 % of the total sulphur and all the
soils were sufficient in sulphur content (based on critical limit value of 10 ppm).
Inorganic sulphate sulphur content extracted with different extractants were in
the following sequence: 0.01M Ca (H2PO4)2 >0.5 M NaHCO3 > 0.15 % CaCl2 >
Morgan’s reagent > 1 N CH3COONH4 extractable sulphur. This revealed that the
phosphorus containing solution extracted more amount of sulphur from soil
because of some adsorbed sulphate also got extracted. Calcium chloride extracted
only soluble sulphate but cannot displace adsorbed sulphate. Similarly, the
ammonium acetate being poor replacer of sulphate, solubilises some of the
inorganic sulphur compounds of the soils. Hence, the amount of extracted
sulphate sulphur content would be low in case of 0.15% CaCl2 and 1 N
CH3COONH4 extractants than others.
Simple correlation studies indicated that the negative relation of pH with
available phosphorus, iron and manganese contents of soils. Organic carbon
content was positive and significantly related with the available N, P, K, Ca, Mg,
S, Zn and Cu contents of soils. Interrelationships were worked out within
different forms of sulphur. Highly significant positive correlations among
different forms were observed. Organic carbon showed significantly positive
relation with all forms of sulphur and sulphate sulphur extracted with different
extractants. Clay and CEC had positive significant relation with different forms
of sulphur and sulphate sulphur. Regression equations indicated that among the
sulphate sulphur extractants showed significant relation and sulphur forms also
showed positive relation with organic carbon.
It was concluded that soil properties (especially pH, OC, clay and CEC)
were the major determinants of sulphur in different forms and sulphur in one
form continues to transform into another maintaining a dynamic equilibrium. The
study indicated that addition of organic manures and incorporation of crop
residues to soils will increase availability of nutrients to the soil and also
improves the availability of sulphur.
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Keywords
sulphur, extraction, inorganic acid salts, carbon, clay, economic resources, nitrogen, sampling, calcium, nutrients