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United States Department of Agriculture (USDA) 2014

TEMPORAL AND SPATIAL VARIATIONS OF SOIL PHOSPHOROUS SPECIATION IN A COLD SEMI-ARID CLIMATE

SOIL PHOSPHOROUS - COLD SEMI-ARID CLIMATE

United States Department of Agriculture (USDA) Research, Education & Economics Information System (REEIS)

Titre : TEMPORAL AND SPATIAL VARIATIONS OF SOIL PHOSPHOROUS SPECIATION IN A COLD SEMI-ARID CLIMATE

Identification : WYO-514-14

Pays : Etats Unis

Durée : Jan 1, 2014 à Sep 30, 2015

Domaine : Soil, Plant, Water, Nutrient Relationships

Partenaire : UNIVERSITY OF WYOMING 1000 E UNIVERSITY AVE DEPARTMENT 3434 LARAMIE,WY 82071-2000

Objectifs
1. Directly determinephosphorus (P)speciation in natural and disturbed rangeland soils under various climate conditions with emphasis on inorganic P speciation determination. 2. Examine seasonal variations of the role of microbes in P cycling in rangeland soils. 3. Uncover how P concentration and speciation have been evolving in rangeland soils at a geological time scale.

Descriptif
1. Directly determine P speciation in natural and disturbed rangeland soils under various climate conditions with emphasis on Pi speciation determinationFifteen natural sites covering a wide range of MAT and MAP values will be chosen from 171 Wyoming weather monitoring stations. Correlations between Pi speciation and climatic variables are expected. Two agriculture- and industry-disturbed soil sites, will be included for comparison with the natural sites to examine how agricultural and industrial disturbances alter P speciation. Three composite samples, each of which will be prepared by mixing three subsamples, will be made to represent the soils at each site. Soils at the depths of 0-10 cm and 10-20 cm will be sampled, leading to 6 composite samples for each site.Soil property measurement will follow the standard soil physical and chemical procedures. A modified sequential Hedley fractionation P sequential chemical extraction will be used to determine P pools. 31P NMR spectroscopy is used to determine Po speciation after Po is extracted from soil samples using a NaOH and Na2EDTA solution. P K-edge XANES spectra will be collected at synchrotron X-ray facilities. The contribution of different P species, represented by standard compounds, to total P will be calculated by XANES Linear Combination Fitting.2. Examine seasonal variations of the role of microbes in P cycling in rangeland soilsA grassland site in the west of Laramie, WY will be selected. A composite soil sample from three subsamples (0-10 cm) will be taken every two weeks, starting from March 1st to October 31st. To evaluate P cycling, d18OPi of the available P pool as well as d18Ow of the H2O in the pore water will be measured. Soil temperatures will be recorded using temperature loggers buried at the site at 5 cm depth. Soil moisture content will be measured using the portable Extech soil moisture meter and soil pore water will be extracted using a suction lysimeter.3. Uncover how P concentration and speciation have been evolving in rangeland soils at a geological time scaleThree soil chronosequences will be chosen to achieve this objective, including alluvial soils containing CaCO3, alluvial soils containing gypsum (CaSO4) but CaCO3, and forest soils, representing the common types of soils in Wyoming. Their ages are 12,000 y - 700,000 y, 5,000 y - 585,000 y and 12,000 y - 600,000 y, respectively. Soil properties, P pools, Po and Pi speciation will be determined using XANES and NMR analyses

Présentation : USDA

Page publiée le 22 octobre 2015, mise à jour le 24 octobre 2017