Date of Award
Doctor of Philosophy (PhD)
Studies were conducted on apparent phosphorus fixation in 54 soils of Louisiana to determine the effects of different rates of P application on the recovery of P, and to develop appropriate regression model for predicting extractable P and recovery of P by using 4 extractants. Soil samples were equilibrated with aqueous solution of P for 7 days, and were then extracted with the 4 solutions. With the exception of the soils of the Mississippi River area, Bray II solution removed significantly larger quantities of P than did the 3 other extractants. Phosphorus removed from soils with the extractants showed wide differences. Extractable P increased with increasing rates of P application. Recovery of P also showed linear relationships in most soils. Only in few soils, the recovery of applied P showed curvilinear relationships. Application of P at rates of 40, 60 and 80 mg kg('-1) gave higher recoveries than did the other rates of P. The 4 solutions were almost equally reliable in extracting P from soils. Regression equations were developed for predicting extractable P and recovery of P with 4 extractants. Investigations were conducted to determine P sorption/desorption characteristics of ten soils of Louisiana. Fifteen gram soils samples were incubated at 25(DEGREES)C with 150 ml of 0.005 M Ca(NO(,3))(,2) solution containing P from 20-200 mg kg('-1) as Ca H(,2)(PO(,4))(,2) (.) H(,2)O for 1-14 days. Quantities of P sorbed and in solution at various incubation times from different rates of P application were determined. Linear regression equations were developed for predicting solution P at 1-14 days following application of P. Time dependence of P were shown by plotting log of solution P vs. time and log of soil P vs. extraction times for sorption and desorption studies respectively. Isotherms were constructed by plotting log of sorbed P against log of solution P at various times for both sorption and desorption studies. Linear regression equations were developed for predicting sorbed P for various levels of solution P in soils. Solubility of P was greater when P was added to soils than when P was desorbed.
Bhuiyan, Mohd. Lukamanur rahman, "Apparent Phosphorus Fixation and Phosphorus Sorption/Desorption Characteristics of Selected Soils of Louisiana." (1985). LSU Historical Dissertations and Theses. 4116.