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Phosphate sorption by Pacific Northwest calcareous soils

LA SORCION DE FOSFATO POR LOS SUELOS CALCAREOS DEL NOROESTE DEL PACIFICO

Leytem, A.B. and Westermann, D.T. (2003) Phosphate sorption by Pacific Northwest calcareous soils. Soil Science. 168(5):368-375.

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Abstract

Understanding phosphorus (P) sorption of calcareous soils is important
for the development of successful fertilizer and manure management
practices. This study was conducted to identify soil chemical properties
controlling P sorption in semiarid calcareous soils of the Pacific Northwest.
Sorption isotherms of 18 primarily calcareous soils ranging widely
in soil physical and chemical properties were constructed by equilibrating
4 g of soil with 40 mL of 0.01M CaC12 containing between 0 and 700
mg P 1.- 1 for 24 h. The P sorption isotherms at low to medium P concentrations
fit the Freundlich isotherm (r2 ? 0.93). The slope of the
isotherm generally increased abruptly at high P concentrations, suggesting
Ca-P precipitation. The maximum P sorption prior to Ca-P precipitation
was closely related to organically complexed Fe and Mn (R2 >
0.98), suggesting that such complexes may regulate P sorption in these
soils. The equilibrium P concentration at the point where Ca-P precipitation
begins to dominate was closely related to pH and organic carbon.
A better understanding of the role of organically complexed metals in
controlling P sorption in calcareous soils is needed to determine how P
solubility is affected by organic matter additions and how this will ultimately
impact the plant availability and potential off-site transport of P
from these soils.

Item Type: Article
NWISRL Publication Number: 1102
Subjects: Soil > Calcareous soil
Soil > Chemistry > Phosphorous
Mass Import - autoclassified (may be erroneous)
Depositing User: Users 5 not found.
Date Deposited: 20 Nov 2010 21:50
Last Modified: 09 Nov 2016 16:12
Item ID: 161
URI: https://eprints.nwisrl.ars.usda.gov/id/eprint/161