TITLE:
Extractable Phosphorus Contents of Some Soils of Bangladesh and Their Correlation with Phosphorus Concentration in Rice Leaves
AUTHORS:
Enamul Haque, Abul Kashem, Khan Towhid Osman
KEYWORDS:
Soil Series; Available P; Olsen P; Mehlich-3 P; Bray & Kurtz-1 P
JOURNAL NAME:
Open Journal of Soil Science,
Vol.3 No.2,
June
4,
2013
ABSTRACT:
To observe the availability of
phosphorus by different extraction methods in some cultivated soils of
Hathazari Upazilla of Chittagong District, this study was carried out with 36
surface soil samples (0 - 15 cm) belonging to six soil series, namely Bijipur,
Pahartali, Mirsarai, Manu, Raojan and Noapara. Physical and chemical
characteristics of the soils were also determined with an objective of
identifying the soil factor(s) regulating P extractability. Three P extraction
methods, namely Olsen (0.5 M
NaHCO3, pH 8.5), Mehlich-3 (0.2 N CH3COOH + 0.013 N HNO3 + 0.015 N NH4F + 0.25 N NH4 NO3 + 0.001 M
EDTA) and Bray & Kurtz-1 (0.03 N NH4F
+ 0.025 N HCl) were used.
There was a wide variation in the extractability of P ranging from low to high
categories. Olsen method extracted the largest amount of P (2.07 - 45.36 mg·kg-1)
while Bray & Kurtz-1 extracted the smallest amount (1.02 - 21.79 mg·kg-1). The mean extractable P in soils was
found to be in the order of Olsen > Mehlich-3 > Bray & Kurtz-1. Soil
pH was the most dominant factor in determining P extractability. Available P
was negatively correlated with percentage of clay, organic carbon and CEC and
positively correlated with pH. Although the three methods extracted different
amounts of P from soil, values of P extracted by the different methods were
strongly correlated among themselves and with the leaf phosphorus concentration
of rice growing in these soils.