Source: UNIVERSITY OF WYOMING submitted to
TEMPORAL AND SPATIAL VARIATIONS OF SOIL PHOSPHOROUS SPECIATION IN A COLD SEMI-ARID CLIMATE
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
MCINTIRE-STENNIS
Reporting Frequency
Annual
Accession No.
1002278
Grant No.
(N/A)
Project No.
WYO-514-14
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jan 1, 2014
Project End Date
Sep 30, 2015
Grant Year
(N/A)
Project Director
Zhu, ME, .
Recipient Organization
UNIVERSITY OF WYOMING
1000 E UNIVERSITY AVE DEPARTMENT 3434
LARAMIE,WY 82071-2000
Performing Department
Ecosystem Science and Management
Non Technical Summary
P deficiency in soils is prevalent in Wyoming, and increasing soil P availability for plant uptake is an important strategy to enhance productivity and sustainability of both agricultural and rangeland ecosystems. P availability relies on its speciation (i.e., chemical forms), and improved understanding of P speciation in soils and its variations with climate, seasons and soil ages is critical to predicting short- and long-term P availability. We are proposing to address: 1) what the P speciation is in natural and disturbed rangeland soils in Wyoming, 2) how the speciation depends on mean annual temperature (MAT) and precipitation (MAP), 3) how the speciation has developed to the current state across soil chronosequences, and 4) whether microbes play an important role in altering the P speciation. Considering the low MAT and MAP regimes in Wyoming and that temperature and water availability affect geochemical reactivity and biological activity in soils, we hypothesize that: 1) inorganic P speciation varies with MAT and MAP regimes, 2) the prevailing model describing P evolution with soil ages, developed for a humid climate, is insufficient to describe that in a semi-arid climate, and 3) microbes play a less important role in P cycling due to the non-optimal environmental conditions for microbial activity. The research will combine both field and laboratory work and will employ state-of-the-art spectroscopic and isotopic approaches. The results are expected to have important influences on sustaining agricultural and rangeland ecosystems. The outcome of the proposed research will include a Ph.D. dissertation, multiple peer-reviewed journal articles, UW CES bulletins, and conference presentations.
Animal Health Component
0%
Research Effort Categories
Basic
60%
Applied
40%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1020110206140%
1020110200020%
1020110204030%
1020110110310%
Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships;

Subject Of Investigation
0110 - Soil;

Field Of Science
2000 - Chemistry; 2040 - Mineralogy; 2061 - Pedology; 1103 - Other microbiology;
Goals / Objectives
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.
Project Methods
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.

Progress 01/01/14 to 09/30/15

Outputs
Target Audience:The research is about phosphorous biogeochemical transformation during ecosystem development. The target audience includes pedologists, soil chemists, soil fertility specialists,ecologists, forest serviceprofessionals, andland management professionals. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project provided opportunities for training a Ph.D. student. He has passed his pre-qualifying exam and will graduate in May 2018. How have the results been disseminated to communities of interest?The results have been presented three times in the Soil Science Society of America annual meetings, one time in the American Chemical Society annual meetiing, and one time in an invited seminar at the University of California -Merced. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? We successfully determinedphosphorous speciation under various conditions using phosphorous X-ray absorption spectroscopy andphosphorous nuclear magnetic resonance spectroscopy. Three manuscripts are in preparation.

Publications

  • Type: Journal Articles Status: Published Year Published: 2016 Citation: ray Absorption Spectroscopic Quantification and Speciation Modeling of Sulfate Adsorption on Ferrihydrite Surfaces C Gu, Z Wang, JD Kubicki, X Wang, M Zhu Environmental Science & Technology 50 (15), 8067-8076
  • Type: Other Status: Published Year Published: 2016 Citation: Mengqiang Zhu and Chunhao Gu, Evaluation of the Phosphorous Bioavailability in Semiarid Soils, 2016 Field Day Bulletin, Wyoming
  • Type: Journal Articles Status: Other Year Published: 2017 Citation: Chunhao Gu, Stephen Hart and Mengqiang Zhu, Phosphorous biogeochemical transformation and effects of aeolian dust, Nature Geoscience, in prep.


Progress 10/01/14 to 09/30/15

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project has been supporting a Ph.D. graduate student. How have the results been disseminated to communities of interest?The results have been presented in academic conferences as well as publication in peer-reviewed journals. What do you plan to do during the next reporting period to accomplish the goals?In the next period, we will spend more time analyzing our data and proceed to writing two research articles.

Impacts
What was accomplished under these goals? During this report period, we used P XANES spectroscopy to determine P speciation for the residual of each Hedley extraction step for soils of different ages collected from the San Francisco Volcano Field, AZ. This allows us to thoroughly characterize what forms of P each extraction step removes for this widely used extraction method for soils. The results show that the HCl-extracted step,which removed the most P from the solids,extracted not only Ca-bound P that has been claimed, but also a significant amount of Fe? and Al-bound P.For the P in the residual of hot concentrated HCL extraction step, P XANES spectroscopy showed that they are mainly Fe and Al-bound P, confirming the conventional viewpoint that has not been proven before. Our results show that the Hedley method is only a way to evaluate P stability, and cannot be used to indicate whether extracted P is associated with Ca, Fe or Al.The results have important implications for interpretation of the Hedley extraction analysis, hence P dynamics in soils. We have determined P speciation usingP XANES spectroscopy forsoils samples of three soil chronosequences located in Wyoming and Arizona. The results suggest that in these soils both Ca-P and Fe-P are significant with neither dominant in P speciation. With increasing soil ages, P speciation does not show an obvious trend; however, the Hedley extraction suggests P speciation evolution is consistent with the Syer and Walker model. We also determined P speciation using P XANES spectroscopy for soils collected from grasslands, Inner Mongolia, China, across a climate gradient. The data is being analyzed and will be presented in the ACS meeting in San Diego, CA 2016

Publications

  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Wang X., Gu C., Feng X. and Zhu M., Sulfate Local Coordination Environment in Schwertmannite, Environ. Sci. Technol., 2015, 49(17):10440
  • Type: Conference Papers and Presentations Status: Other Year Published: 2015 Citation: Gu C., Wang X., Zhu M., Identification and quantification of sulfate surface complexes on ferrihydrite, 249th ACS National Meeting, Denver, CO, March 22-26, 2015. Oral presentation
  • Type: Conference Papers and Presentations Status: Other Year Published: 2015 Citation: Wang X., Gu C., Feng X. and Zhu M., The Sulfate coordination environment in Schwertmannite, 249th ACS National Meeting, Denver, CO, March 22-26, 2015. Oral presentation


Progress 01/01/14 to 09/30/14

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project has been training a Ph.D student at the University of Wyoming and a visiting Ph.D. student from China. How have the results been disseminated to communities of interest?The results were presented in the Soil Science Socieity of America annual meeting in Long Beach in 2014. What do you plan to do during the next reporting period to accomplish the goals?We will strive to publish the data we have collected during the next reporting period.

Impacts
What was accomplished under these goals? We have accomplished the following: 1) Directly determined P concentration and speciation changesin natural rangeland soils at a geological time scale 2) The samplesacross a climate gradient were measured at the Canadian Light Source. 3) We measured P speciation in the dust samples that were provided by the USGS in Denver. Phosphorus (P) is a crucial nutritional element for life on earth. Almost all the P in terrestrial ecosystems is derived from rock weathering during soil genesis. The developmental stages of soils control P concentration, most importantly, its speciation and bioavailability in soils. P speciation transformation with time during soil genesis in humid ecosystems is relatively well known, which can be described by the conceptual model proposed by Walker and Syers. However, limited information is available about P speciation change in semi-arid ecosystems. Sequential chemical extractions (SCE) have been widely used to assess and quantify soil P species with different binding types and bioavailability. But SCE provides only operationally-defined P pools, and does not directly determine P speciation. Synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy is an efficient and direct approach that can distinguish different P species, particularly solid inorganic P (Pi) species, in environmental samples, such as soils. 31P nuclear magnetic resonance (31P NMR) spectroscopy is another technique that is powerful for determining speciation of extractable organic P (Po) in soils. In this project, we have determined soil P speciation from two soil chronosequences in a semi-arid natural environment using P XANES and 31P NMR spectroscopic analyses in addition to SCE. Surface soils were collected from two chronosequence sites that are located in the Laramie Basin, Wyoming and the San Francisco Volcanic Field, Arizona, respectively. The ages of the investigated soils range from 0.14 million years (MY) to 1.8 MY for the basin, and from 0.01 MY to 3 MY for the volcanic field, respectively. Results show that total soil P concentrations decreased with the substrate age. The Fe-bound P is significant even from the youngest soils, suggesting dust deposition is another important P source in soils in a semi-arid environment.31P NMR suggests that inositol P is the main form of organic P and its concentration increases first and then decreases. In summary, our results indicate the aoelian dust deposition significantly affects P speciation, making the P speciation evoluton with soil ages deviate from the prediction of the classic Syer and Walker model.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Gu C., Munn L.C., Hart S.C., Hu Y. and Zhu M., Phosphorus Speciation during Soil genesis in a Semi-arid Environment, ASA, CSSA and SSSA International Annual Meeting, Long Beach, November 2-5, 2014, Oral presentation
  • Type: Journal Articles Status: Accepted Year Published: 2015 Citation: Wang X., Gu C., Feng X. and Zhu M., Sulfate Local Coordination Environment in Schwertmannite, Environ. Sci. Technol. 2015 (Accepted)