STUDIES ON THE SOIL PHOSPHORUS STATUS AND PHOSPHORUS FRACTIONS UNDER DIFFERENT CROPPING SYSTEMS IN SOUTHERN ZONE OF A.P.
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Date
2019
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ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR
Abstract
The present investigation entitled “Studies on the soil phosphorus status and phosphorus fractions under different cropping systems in Southern Zone of A.P.” was conducted to study the physico-chemical properties of soils, status of available P2O5 and different forms of P collected under different crops/cropping system in Southern Zone of A.P. (Chittoor, Y.S.R. Kadapa and S.P.S.R. Nellore districts). Five soil samples from each crop / cropping system at 0-15 cm depth were collected. In non-calcareous soils of Chittoor district, the highest mean pH (6.61) value was recorded in groundnut+redgram cropping system, whereas, in calcareous soils, it was highest (7.92) in paddy-groundnut cropping system. In calcareous soils of Y.S.R. Kadapa district, the highest pH (8.36) mean value was recorded in groundnut monocropping system whereas, in calcareous soils of S.P.S.R. Nellore district, it was highest (8.18) in fallow-blackgram system. In all the districts, the electrical conductivity (EC) measured was nonsaline and below the critical limits. In non-calcareous soils of Chittoor district, the highest free CaCO3 mean value (4.9%) was recorded in groundnut+redgram system and in calcareous soils, it was highest (6.8%) in bajra-groundnut system. In calcareous soils of Y.S.R. Kadapa district, the highest CaCO3 mean value (11.8%) was recorded in groundnut monocropping system, whereas, in calcareous soils of S.P.S.R. Nellore district it was highest in fallowbengalgram system (15.2%). In non-calcareous soils of Chittoor district, the highest mean values for available P2O5 (189.66 kg ha-1), saloid P (16.35 mg kg-1), Fe-P (50.24 mg
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kg-1) were obtained in groundnut monocropping system and Al-P (40.71 mg kg-1) , total-P (574.07 mg kg-1), Ca-P (39.56 mg kg-1) and other forms of P (434.86 mg kg-1) was obtained in groundnut+redgram cropping system. In calcareous soils of Chittoor district, the highest mean values for saloid-P (28.28 mg kg-1), Fe-P (50.68 mg kg-1), total-P (490.28 mg kg-1) and other forms of P (406.44 mg kg-1) were recorded in sugarcane monocropping system and available P2O5 (113.57 kg ha-1) and Ca-P (108.26 mg kg-1) were recorded in bajra-groundnut cropping system. In calcareous soils of Y.S.R. Kadapa district, the highest mean values for available P2O5 (182.41 kg ha-1), Al-P (80.82 mg kg-1), Ca-P (118.55 mg kg-1) and total-P (434.35 mg kg-1) were recorded in groundnut monocropping system whereas for saloid P (23.01 mg kg-1), Fe-P (69.82 mg kg-1) and other forms of P (228.35 mg kg-1) the highest mean values were obtained in sunflower-sesame, groundnut-groundnut and fallow-bengalgram cropping systems, respectively. In calcareous soils of S.P.S.R. Nellore district, the highest mean values for saloid P (16.67 mg kg-1), total-P (538.21 mg kg-1) and other forms of P (342.07 mg kg-1) were recorded in groundnut-paddy cropping system and FeP (68.77 mg kg-1) and Al-P (61.85 mg kg-1) were highest in paddy-paddy cropping system, whereas available P2O5 (166.82 kg ha-1) and Ca-P (173.15 mg kg-1) were highest in groundnut-paddy and fallow-bengalgram systems, respectively. In non-calcareous soils of Chittoor district, pH showed positive significant correlation with all the P fractions. Under all the cropping systems, all forms of P had positive and significant correlation with EC. Free CaCO3 showed positive and significant relation with Ca-P (r= 0.539*). Available P2O5 showed highly significant and positive correlation with saloid-P (r= 0.781**), Al-P (r= 0.809**), Fe-P (r= 0.611**) and Ca-P (r= 0.709**). Whereas saloid-P showed significant and positive correlation with Fe-P (r= 0.694**) and Al-P (r= 0.749**), Fe-P showed positive and significant correlation with Ca-P (r= 0.747**), and Al-P showed positive and significant relation with total-P (0.627**). Free CaCO3 showed positive and significant correlation with saloid-P (r= 0.601**) and Ca-P (r= 0.603**) in calcareous soils of Chittoor district. Available P2O5 showed positive and significant correlation with Al-P (0.571*) and Ca-P (0.523*), whereas, saloid-P showed significant and positive correlation with Fe-P (r= 0.725**) and total-P (r= 0.734**), Fe-P showed positive and significant correlated with total-P (r= 0.959**) and other forms of P (r= 0.958**). Total-P showed positive and significant relation with other forms of P (r= 0.974**). In calcareous soils of Y.S.R. Kadapa district, pH showed positive and significant correlation with other forms of P (r= 0.413*), available P2O5 showed positive and significant correlation with Al-P (r= 0.893**), Fe-P (r= 0.823**), Ca-P (r= 0.766**) and total-P (r= 0.651**). Al-P showed positive and significant correlation with Fe-P (r= 0.916**), Ca-P (r= 0.473*) and total-P (r= 0.554**) whereas Fe-P showed significant and positive
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correlation with Ca-P (r= 0.543**) and total-P (r= 0.643**). Ca-P showed positive and significant correlation with total-P (r= 0.705**), total-P showed positive and significant relation with other forms of P (r= 0.790**). pH showed positive and significant relation with total-P (r= 0.507**) and other forms of P (r= 0.573**) where as free CaCO3 showed positive and significant correlation with Ca-P (r= 0.432*) in calcareous soils of S.P.S.R. Nellore district. Available P2O5 showed positive and significant correlation with saloid-P (r= 0.456*), Al-P (r= 0.765**) and Fe-P (r= 0.559**), saloid-P showed significant and positive correlation with total-P (r= 0.477*) and other forms of P (r= 0.510**). Al-P showed positive and significant correlation with Fe-P (r= 0.885**). Similarly, Ca-P showed positive and significant relation with total-P (r= 0.418*).
Description
D5883
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