Organic phosphorus composition and potential bioavailability in semi-arid arable soils of the Western United States

Fósforo Orgánico, Composición y Biodisponibilidad en Suelos Arables Semi-Áridos del Oeste de Estados Unidos

Turner, Benjamin L. and Cade-Menun, Barbara J. and Westermann, Dale T. (2003) Organic phosphorus composition and potential bioavailability in semi-arid arable soils of the Western United States. Soil Science Society of America Journal. 67:1168-1179.

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Abstract

The organic P composition of semi-arid arable soils is largely unknown,
but such information is fundamental to understanding P dynamics
in irrigated agriculture. We used solution "P nuclear magnetic
resonance (NMR) spectroscopy and phosphatase hydrolysis to characterize
organic P in semi-arid arable soils from the western USA (organic
C 2.0-30.7 g C kg' soil, clay 2-48%, pH 5.2-8.2, CaCO 3 <1-480 g
kg -' soil). Total P concentrations ranged from 220 to 1210 mg P kg-1
soil, of which between 12 and 45% was extracted with NaOH-EDTA.
Inorganic orthophosphate was the dominant P compound, but concentrations
determined by solution 31P NMR spectroscopy were consistently
greater than those determined by molybdate colorimetry. Concentrations
of organic P were relatively small, and were dominated
by orthophosphate monoesters (11-130 mg P kg-1 soil), with smaller
concentrations of orthophosphate diesters (0-7 mg P kg-1 soil). Pyrophosphate
was present in almost all soils at concentrations up to 14 mg
P kg-1 soil. Bicarbonate-extractable organic P ranged from 1.7 to
22.8 mg P kg-1 soil, of which between 37 and 87% was hydrolyzed
by phosphatase enzymes, suggesting its bioavailability. Soil organic
P concentrations were positively correlated with mean annual precipitation,
organic C, clay, and oxalate-extractable metals (Al, Fe, Mn),
and negatively correlated with mean annual temperature and soil pH.
However, CaCO3 concentrations were not significantly correlated with
any soil property. These results indicate that equilibrium levels of
organic P in semi-arid arable soils are controlled by a balance between
the physical protection offered by the soil matrix and the suitability
of the environment for biological productivity

Item Type:	Article
NWISRL Publication Number:	1104
Subjects:	Soil > Chemistry > Phosphorous Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:50
Last Modified:	08 Nov 2016 20:10
Item ID:	162
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/162