Apparent phosphorus fixation by selected soils of Louisiana

Abstract

Investigations were conducted to determine the effects of different rates of phosphorus (P) application on extractable P and to develop regression models for predicting extractable P by using the Bray I, Bray II, Double Acid (Mehlich No. 1), and Modified Olsen extradants on 54 agricultural important soils of Louisiana. Soil samples were equilibrated with an aqueous solution P at the rates of 0, 20, 20, 60, 80, and 100 mg/kg for 7 days and were then extracted with the four extradants. The Bray II extradant, in general, extracted significantly larger quantities of P than did the three other extradants with exception to the soils of the Mississippi River areas. Extractable P increased significantly with increasing rates of P application, but recovery of P did not increase with rates of P application.

The Bray II solution generally extracted significantly larger quantities of P than did the three other extractants with exception of the soils of the Mississippi River areas. Extractable P increased significantly with increasing rates of P application, but recovery of P did not increase with rates of P application. Application of P at rates of 40, 60, and 80 mg/kg resulted in relatively higher recoveries of P than did the other rates of P.

Linear relationships were found between extractable and applied P. Similar regression slopes and high r² values of the linear relationship between extractable and applied P indicated reliability of the four extradants to extract applied P were similar. The four extractants differed greatly in their ability to extract native P from the soils. Recovery of P showed relatively small differences among the extradants.

Notes

Dissertation research conducted at the Agronomy Department, Louisiana State University, Baton Rouge, LA 70803 and contribution of the Louisiana State Project 1835.

Former Graduate Student Agronomy Department, LSU, Baton Rouge, LA 70803. Currently Principal Agronomist, Bangladesh Rice Research Institute Gazipur‐1701, Bangladesh.

Professor.