Phosphorus release characterstics, forms and plant uptake in Alfisols of deferential P status
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Date
07-10-11
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University of Agricultural Sciences GKVK, Bangalore
Abstract
The different forms of phosphorus were determined in soils varying in P status
(high, medium and low). The soils varying in P status was collected from three villages
of Bangalore rural taluk, namely Kariberanahoshalli (high P soil), Devanahalli (medium
P soil) and Devanahahalli (low P soil) respectively. Similarly three such types of soils
were collected from different locations in GKVK campus of University of Agricultural
Sciences Bangalore. The soils were sourced from horticulture plot (high P soil), AICRP
on soil test and crop response plot (medium P soil) and Sericulture plot (low P soil).
The results showed that he bulk density (1.40 Mg m-3), available P and K (161.00
and 336.90 kg ha-1) respectively, phosphorus buffering capacity (26.20%) and Fe-P
(79.56 mg kg-1) were high in the high P soil of Kariberanahoshalli, Bangalore rural taluk.
The particle density (3.00 Mg m-3), pH (6.85), available N (334.90 kg ha-1),
exchangeable Ca (4.85 cmol P+ Kg-1) and Al-P (86.62 mg kg-1) were high in medium P
soil of Devanahalli, Bangalore rural taluk. The maximum water holding capacity (40.29
%), cation exchange capacity (15.4 cmol P+ Kg-1), total P (268.70 mg kg-1) and occld-P
(19.34 mg kg-1) were high in low P soil of Devanahahalli, Bangalore rural taluk.
In GKVK campus soils, the MWHC (33.10 %), pH (6.7), exchangeable Ca (4.20
cmol P+ Kg-1), and available S (19.50 mg kg-1) were high in high P soil of horticulture
plot. The available P (51.80 kg ha-1), total P, Fe-P and Ca-P (411.65, 89.21 and 14.19 mg
kg-1) respectively were high in medium P soil of on soil test and crop response plot. The
BD (1.35 Mg m-3), pH (5.60), exchangeable Ca and Mg (4.50 and 2.30 cmol P+ Kg-1),
Al-P and RS-P (59.21 and 42.00 mg kg-1) were high in low P soil of Sericulture.
The change of P fractions during period of cowpea growth in the soils of varying
P status was evident. This was indicated by the change in the order of the fractions in the
initial (Al-P > Fe-P > RS-P > Occld-P > Sal-P > Ca-P) and residual (Al-P > Fe-P > RS-P
> Occld-P > Ca-P > Sal-P) soil samples.