Phosphorus sorption of some flooded rice soils in Laguna

Abstract

Effectiveness of the usual P fertilizer rate recommended for flooded rice is uncertain. Any soil information that may lead to improved fertilizer management practices for flooded rice is therefore important in improving rice yields in the Philippines. In this study, soil samples from flooded rice fields in Laguna were equilibrated with solutions of various P concentrations to: determine their P sorption parameters and relationship with some soil properties, and estimate P requirement based on P sorption parameters. The soil samples showed varying pH, clay and organic matter content, 0.5 M NaHCO3-extractable P content, and P sorption characteristics including P adsorption maximum (Kmax), P retention from a standard 1,000 ppm P solution (Pret), and P sorption at equilibrium solution P concentration of 0.02 ppm (P0.02). Kmax and P0.02 were strongly associated with pH. Both P0.02 and Kmax could be predicted by Pret. Estimated P requirement generally did not agree with the usual recommendation of 13 kg P/ha. Only 25 % of the samples showed similar rate of P fertilizer requirement based on P0.02 and Olsen P extraction. For some of the soil samples requiring at least 13 kg P/ha based on Olsen P, the rate of P fertilizer requirement based on P sorption data were very small (<4.4 kg P/ha) that perhaps may be ignored until soil P level has significantly decreased.

Source or Periodical Title

Philippine Agricultural Scientist

ISSN

317454

Page

159-167

Document Type

Article

Subject

Flooded soils, Phosphate adsorption maximum, Phosphorus requirement, Phosphorus retention, Soil solution phosphate

This document is currently not available here.

Share

COinS