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Transformations of Inorganic Phosphorus During the Flooding and Draining Cycles of Soil
Author(s) -
Sah R. N.,
Mikkelsen D. S.
Publication year - 1986
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1986.03615995005000010012x
Subject(s) - soil water , phosphorus , chemistry , zoology , drainage , anoxic waters , oryza sativa , agronomy , environmental chemistry , geology , soil science , biology , ecology , biochemistry , gene , organic chemistry
Phosphorus transformations that occur after anoxic soils are drained have been associated with acute P deficiencies in rotation crops following rice. Flooded rice may not respond to P fertilization while rotation crops respond markedly to P fertilization on similar soils. The changes that occur among the inorganic P forms during flooding and after drainage in four soils were investigated. Significant changes in the inorganic P fractions—aluminum‐P (Al‐P), iron‐P (Fe‐P), calcium‐P (Ca‐P), and reductant soluble‐P (RS‐P) occurred in soils during their flooding and draining cycles. Typically, the Fe‐P fractions increased and Al‐P fractions decreased when soils were flooded. The Ca‐P fraction increased during flooding in two soils that had initially high levels of Ca‐P but was almost unchanged in two other soils of lower Ca‐P content. The RS‐P fraction decreased during flooding in the soils subjected to annual flooding. During the drainage period, Fe‐P and Al‐P fractions decreased and the RS‐P fraction increased in flooded rice‐cropped ( Oryza sativa L.) soils, probably due to occlusion of Fe‐P and Al‐P by hydrated Fe and Al oxides. The RS‐P fraction in Willows clay, a soil that had not been flooded recently, decreased during the drainage period. Phosphorus added as Ca(H 2 PO 4 ) 2 . H 2 O was recovered mainly in the Fe‐P and Al‐P fractions. The recovery of Fe‐P was greater in flooded‐drained soils and Al‐P was greater in unflooded soils.