Do Decomposing Organic Matter Residues Reduce Phosphorus Sorption in Highly Weathered Soils?

Title
Do Decomposing Organic Matter Residues Reduce Phosphorus Sorption in Highly Weathered Soils?
Publication Date
2005
Author(s)
Guppy, C
( author )
OrcID: https://orcid.org/0000-0001-7274-607X
Email: cguppy@une.edu.au
UNE Id une-id:cguppy
Menzies, NW
Blamey, FPC
Moody, PW
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Soil Science Society of America
Place of publication
United States of America
DOI
10.2136/sssaj2004.0266
UNE publication id
une:330
Abstract
Many studies have shown a reduction in P sorption in highly weathered soils when organic matter (OM) is applied, suggesting competition between OM decomposition products and P for sorption sites. However, such studies seldom consider the P released from the added OM. To delineate the effects of OM addition on P availability through sorption competition and P addition, water leachate from incubated soybean (SB) [Glycine max (L.) Merr.] and Rhodes grass (RG) (Chloris gayana Kunth cv. Callide) was used in competitive P sorption studies both undiluted and after acidification (i.e., the fulvic acid [FA] component). Addition of two rates (0.2 and 2 mL) of SB leachate to an Oxisol significantly increased P sorption at the higher rate, while a similar trend was observed following RG leachate addition at the same rates. Extending the range of highly weathered soils examined (two Oxisols, an Ultisol, and an acidic Vertisol) resulted in no observed decrease in P sorption following addition of OM leachate. Surprisingly, SB leachate transiently increased P sorption in the two Oxisol soils. Addition of the FA component of the leachates resulted in a transient (<6 d) decrease in P sorption in three of the four soils examined and constituted the only evidence in this study that decomposing OM residues reduced P sorption. This research provides further evidence contradicting the long held assumption that inhibition of P sorption by dissolved organic compounds, derived from decomposing OM, is responsible for increased P phytoavailability when P fertilizer and OM are applied together.
Link
Citation
Soil Science Society of America Journal, 69(5), p. 1405-1411
ISSN
1435-0661
0361-5995
Start page
1405
End page
1411

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