Skip Navigation LinksHome > April 2008 - Volume 173 - Issue 4 > ORGANIC AMENDMENTS INCREASE SOIL SOLUTION PHOSPHATE CONCENTR...
Soil Science:
doi: 10.1097/SS.0b013e31816d1e3b
Technical Articles

ORGANIC AMENDMENTS INCREASE SOIL SOLUTION PHOSPHATE CONCENTRATIONS IN AN ACID SOIL: A CONTROLLED ENVIRONMENT STUDY

Schefe, Cassandra R.1; Patti, Antonio F.2,3; Clune, Timothy S.1,4; Jackson, Roy2

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Abstract

Soil acidification affects at least 4 million hectares of agricultural land in Victoria, Australia. Low soil pH can inhibit plant growth through increased soluble aluminum (Al) concentrations and decreased available phosphorus (P). The addition of organic amendments may increase P availability through competition for P binding sites, solubilization of poorly soluble P pools, and increased solution pH. The effect of two organic amendments (lignite and compost) on P solubility in an acid soil was determined through controlled environment (incubation) studies. Three days after the addition of lignite and compost, both treatments increased orthophosphate and total P measured in soil solution, with the compost treatments having the greatest positive effect. Increased incubation time (26 days) increased soil solution P concentrations in both untreated and amended soils, with the greatest effect seen in total P concentrations. The measured differences in solution P concentrations between the lignite- and compost-amended treatments were likely caused by differences in solution chemistry, predominantly solution pH and cation dynamics. Soil amendment with lignite or compost also increased microbial activity in the incubation systems, as measured by carbon dioxide respiration. Based on the results presented, it is proposed that the measured increase in soil solution P with amendment addition was likely caused by both chemical and biological processes, including biotic and abiotic P solubilization reactions, and the formation of soluble organic-metal complexes.

© 2008 Lippincott Williams & Wilkins, Inc.

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