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FERTILITY EVALUATION OF SOILS OF TENALI DIVISION, GUNTUR DISTRICT WITH SPECIAL REFERENCE TO PHOSPHORUS

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Title FERTILITY EVALUATION OF SOILS OF TENALI DIVISION, GUNTUR DISTRICT WITH SPECIAL REFERENCE TO PHOSPHORUS
 
Creator OMKAR VINAY KUMAR, T
 
Contributor PRASAD, P.R.K.
 
Subject Fertility, soils, Phosphorus
 
Description Research work was carried out to evaluate the fertility status in soils of Tenali division, Guntur district with special reference to phosphorus status. Hundred and fourteen soil samples were collected in representative areas of the division by using revenue map of Tenali division. The soil samples were analyzed for their physicochemical properties and extraction of phosphorus with different extractants. The extractants used for phosphorus extraction were Olsen, Bray 1, Mehlich 3 and Soltanpour and for potassium extraction were ammonium acetate and AB-DTPA. Correlation studies were also carried out among phosphorus and potassium extracted by different extractants and soil properties.
The results indicated that 38 per cent of soils were neutral, 5 per cent were acidic, while the remaining 57 per cent of the samples were alkaline in soil reaction. All the samples were non-saline except one sample. The soils were low in organic carbon and available nitrogen, high in available phosphorus and potassium. Among the exchangeable basic cations, Ca was dominant followed by Mg, K and Na. Available sulphur was well above the critical limit. AB-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 with medium to high cation exchange capacity. Texturally they were sand, loamy sand, sandy clay loam, sandy clay and clay showing wide variation in texture.
Among different P extractants, maximum amount of phosphorus was extracted by Olsen’s extractant followed by Soltanpour, Mehlich 3 and Bray 1. Among these extractants, Bray 1 reagent extracted more P from acid soils and in case of neutral and alkaline soils, Olsen’s test extracted high amount of P followed by Soltanpour, Mehlich 3 and Bray 1. Across all the soils (114 samples-pH ranged from 5.6 to 8.5), the overall
correlations for different P extractants were also worked out. The relation for Olsen-P vs Bray1-P was not significant, Olsen-P vs Mehlich3-P was significant, while Olsen-P vs Soltanpour-P, Bary1-P vs Soltanpour-P, Soltanpour-P vs Mehlich3-P and Mehlich3-P vs Bray1-P were highly significant. In case of K extractants, ammonium acetate extracted relatively higher amounts of K compared to AB-DTPA. The relation between amounts of K removed by ammonium acetate and AB-DTPA were highly significant and positively correlated.
Simple correlation studies indicated that soil pH had negative correlation with sand, bulk density, CEC, OC, CaCO3, available nitrogen, phosphorus, zinc, and copper contents, but this correlation was found significant only with sand, bulk density, CEC, OC, CaCO3, available nitrogen and copper. The pH was positively correlated with water holding capacity, clay, iron and manganese. Interrelationships worked out within different extractants of phosphorus showed highly significant positive correlation among themselves except Olsen with Bray 1. All the P extractants were significantly and positively correlated with organic carbon except Bray 1 and negatively correlated with pH, clay, CaCO3 and CEC. Organic carbon content was positively correlated with all available nutrients. It was found that the organic carbon of soils was the major contributing factor towards the availability of various macro as well as micronutrients and hence, maintenance of organic matter of the soil is essential to sustain the soil fertility and to enhance the productivity.
A biological study was conducted using Neubauer seedling technique with wheat as test crop to evaluate the efficiency or suitability of P extractants with biological parameters for these soils of Tenali division. The dry matter accumulation was maximum and minimum in wheat seedlings grown in neutral soils and acid soils, respectively. This trend could be due to pH of the soils. The average P uptake was maximum in wheat grown in neutral soils and minimum in the plants grown in acid soils and the average K uptake was maximum in wheat grown in alkaline soils and minimum in the plants grown in acid soils.
To-day’s challenge is to select from the collection of soil extraction tests such methods that allow simultaneous extraction of several nutrients. From results of the present study, it could be concluded that the AB-DTPA test is suitable for P extraction for all groups of soils of Tenali division. However, the use of AB-DTPA test for extraction of P and K for the soils must be based on the detailed correlation and calibration work using crop yield data obtained from field experiments.
 
Date 2016-12-22T10:28:35Z
2016-12-22T10:28:35Z
2014
 
Type Thesis
 
Identifier 208P.
http://krishikosh.egranth.ac.in/handle/1/92046
 
Language en_US
 
Relation D5073;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY