Availability of Phosphorus in Alfisol in Bihar
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Date
1996
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Birsa Agricultural University, Ranchi
Abstract
A series of laboratory experiments with respect to phosphorus status, its relationship with important soil properties and inorganic P fractions were carried out in the soils of Pusaro series of Santhal Parganas region of Bihar Attempts have been made to characterize the soils in relation to surface P adsorption and relationship of Langmuir constants to soil properties were studied. Green house experiments were conducted to study the differential response of three pulse crops to P application. Results indicate that the soil of Pusaro series are strong to moderately acidic in reaction, poor in organic matter content with sandy loam texture. The available P (Bray P.) content of soils ranged from 0.3 to 24.0 mg kg and are categorized as of low to medium P status.
Correlation studies between available phosphorus and soil properties show that soil pH has positive and significant (r= 0.358) correlation with available P. Relationship of available P with different inorganic P fractions indicate significant positive relationship with Al-P, Fe-P and Ca-P and significant negative relationship with R-P.
Results of P adsorption study indicate that these soils follow the Langmuir adsorption isotherm. The phosphorus adsorption maxima varies from 260.5 to 780.6 g P g' soil while bonding energy constant ranged from 4.35 to 10.40 ppm (x103). P adsorption maxima is significantly and positively correlated with organic carbon (r= 0.463*) and clay content (r= 0.687*) of soil and related significantly and negatively with sand (r= 0.688*) and available P content (r= -0.430*) of soils. The bonding energy constant of phosphorus relates significantly and positively with organic carbon, clay, silt and available P content and negatively with sand content of soils.
Results of greenhouse studies conducted on different pulse crops in Alfisols shows significant response to phosphorus, the maximum dry matter and P uptake response is observed in case of Urd. The results further show that per cent P uptake response increased upto 60 mg P ka level, thereafter it started decreasing.