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United States Department of Agriculture

Agricultural Research Service

Research Project: UNDERSTANDING PHOSPHORUS CHEMISTRY IN MANURE AND SOIL AND THEIR INTERACTIONS TO TREAT AND CONTROL PHOSPHORUS MOVEMENT IN THE ENVIRONMENT
2006 Annual Report


1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter?
The in house project 1265-12360-002-00D is conducted under National Program 206 to develop a basic understanding of the chemistry of phosphorus in manure and soil and their interactions in controlling the behavior of environmental phosphorus. In areas of intensive animal production, agricultural soils can become phosphorus-enriched because of continuous manure applications over the years. The near-surface zone accumulates and shows elevated levels of inorganic and organic phosphorus. Animal manures are major sources of organic phosphorus that is composed primarily of salts of phytic acid (phytate) and, in smaller proportion, phosphorylated lipids and phosphate diesters. These compounds are the major forms of stored phosphorus in plant materials. Animal manures, composed of partially digested feeds of plant origin, are attracting a great deal of interest because of the inefficiency of animal digestive systems in absorbing or retaining phosphorus, in particular phytic acid. Phytic acid is excreted in animal manure because swine and poultry lack the phytase enzymes to break down phytic acid. Manure from ruminant livestock, thought able to utilize phytic acid-phosphorus because of microbial hydrolytic activity in the rumen and intestinal lining of the lower gut, also contains significant amounts of organic phytase-hydrolysable phosphorus. As a result, substantial amounts of phytic acid of feed grains are excreted in feces and contribute to non-point source pollution rather than animal growth. In agricultural fields amended with manure, phytic acid and other organic phosphorus are added to the near-surface soil phosphorus pool, in addition to inorganic phosphate. The need for detailed organic phosphorus characterization studies is critical because inositol phosphate monoesters and orthophosphate diesters have been observed to move through soils and to contribute to the risks of water quality degradation via subsurface movement, in addition to overland movement to surface waters such as streams, lakes, and estuaries. Although there have been many studies on the composition and fate of inorganic phosphorus in manure and manure-amended soil, speciation and mineralization of organic phosphorus compounds are yet poorly understood. The knowledge gap hampers the understanding of the environmental behavior and transformations of inositol phosphates, in particular phytic acid in animal feed, manure, soil, water, and mixed environmental media. Thus, the development of comprehensive strategies for mitigating agricultural phosphorus diffuse transfers and protracted contamination of natural aquatic systems. A Phosphorus Site Index (PSI) is used by state agencies as a nutrient management tool to assess the risk of phosphorus transport from soil to aquatic systems prior to land application of animal manures. A critical element of the PSI, yet to be developed, is a phosphorus availability coefficient that functions as a rough-cut weighting factor accounting for relative differences in water solubility of the many forms of P in manure of different livestock species and manure handling and storage systems. It is intended for estimating the proportion of applied P that may be subject to loss via overland transport in runoff.

In summary, the planned research contributes to the development of methods for determining content and bioactivity of phosphorus forms, controls of solubilization in manure and manure-amended soils, nutrient immobilization and the potential solubilization and release of immobilized phosphorus, manure phosphorus recovery techniques based on new knowledge of the chemistry of phosphorus, and transformations and interactions with soil components. The new experimental results will be integrated into predictive tools for evaluating organic phosphorus and carbon availability, whole-farm nutrient accumulation, leaching and overland transport potentials. It is anticipated that the research results will improve the quality of the environment by helping farmers more efficiently manage their animal manure, and assisting nutrient management specialists in strategic planning for determining nutrient accumulation and assimilation capacities, and assessing phosphorus dynamics and loss vulnerability from site-specific characteristics at field, whole-farm and regional scales in watersheds where water quality is impaired or threatened by agricultural activities across the US.


2.List by year the currently approved milestones (indicators of research progress)
2006: Per project plan, perform field soil, manure collection. Manure fractionation and identification of bioactive phosphorus in feed and cattle and poultry manure (Objective 1a).

2007: Determine near- and mid-infrared spectral signatures of P forms and the condensation and solubility of organic phosphorus (Objective 2).

2007: Develop calibration for forms of inorganic- and organic-P measured by traditional assays. Relate bioactive forms to near- and mid-infrared characteristic spectral attributes (Objective 2).

2009: Evaluate zeolitic by-products characteristics and efficiency of removal and recovery systems as function of wastewater chemistry (Objective 3a).

2007: Collect, characterize, and incubate by-products, soils, and manures. Determine re-solubilization of immobilized phosphorus (Objective 3b).

2008-2010: Expose amended soil and manure to fluctuating environmental conditions. Determine stability and re-solubilization of immobilized phosphorus (Objective 3b).

2007-2010: Derive soil and bioactive phosphorus algorithms from mineralization study (Objectives 1c and 4). Evaluate current P models and refined RZWQM (Objective 4).


4a.List the single most significant research accomplishment during FY 2006.
A rapid X-ray method for phosphorus in animal manures: A robust X-ray fluorescence method was developed to measure phosphorus non-destructively in dry cattle manure, poultry litter, and feed samples that are very variable in physical state and composition. Simultaneously, the content of many other mineral constituents such as calcium, potassium, iron, aluminum, copper, zinc, etc... in the samples can be determined to explain differences in the release and availability of P from manures of animals receiving feed rations of varied composition and mineral supplements. The method can also be used for soil samples, particularly in soil amended with manures or other organic by-products. The X-ray fluorescence method detected the effects of different handling and storage conditions on the composition of manure and subsequent mineralization and release of phosphate. The spectrometric method is eventually transportable to the field for on-site analysis of phosphorus and other minerals in manures, making it possible for analysis of specific manure batch by farmers. Along with the phytase enzymatic assay developed by EMBUL scientist, availability of bioactive P forms in such materials can be determined. This research contributed directly to the Nutrient Management Component, Problem Area 3, Managing Tools for Indexing and Evaluating Nutrient Fate and Transport of National Program 206.


4b.List other significant research accomplishment(s), if any.
Bioavailability of immobilized phosphorus in soil: Additives rich in spent aluminum or iron such as drinking water treatment residuals or coal ashes can lower water and plant-extractable phosphorus (P) in manure and P-enriched soils. An enzymatic assay and P fractionation study was conducted to determine the effects of calcium as lime and iron amendments on extractable P levels in high-P soils. The phytase enzymatic assay, developed in EMBUL revealed that the iron additives’ effect was transient; organic P becomes increasingly exchangeable over time to revert to their initial levels. As traditional soil test methods did not account for these temporal changes, the ligand-based enzyme-labile method was a more appropriate biological tool to detect internal biochemical changes in the susceptibility of soil inorganic and organic P forms in efforts to develop manure management practices and P transport mitigation strategies. This research contributed directly to the Nutrient Management Component, Problem Area 2 (Innovative Technology for collection, storage, and treatment) and Problem Area 3 (Managing Tools for Indexing and Evaluating Nutrient Fate and Transport) of National Program 206.

Improving the Phosphorus Site Index used by States to determine risks of manure phosphorus loss: EMBUL scientists conducted a laboratory study to determine phosphorus availability coefficient (PAC) values using selected extractants for a variety of manures, and assess the efficacy of PAC values in predicting P runoff losses. Coefficients were determined following 14 and 56-day incubations of samples of a Mattapex soil amended with six manures and triple superphosphate. Under simulated rainfall, P levels in runoff were measured and related to PAC values to determine which value is the best predictor of runoff losses. Coefficients based on water extraction or laboratory soil test P methods ranged between 28 to 78% after 14 days of incubation. Also, the results suggested that the influence of soil properties on the release of P to runoff from different manures largely depended on the timing of the first rain that generates runoff. Manure characteristics dominated the release process while soil properties increased in importance and controlled the release in the long-term. This research contributed directly to the Nutrient Management Component, Problem Area 3, Managing Tools for Indexing and Evaluating Nutrient Fate of National Program 206.


4c.List significant activities that support special target populations.
EMBUL scientists participated in the framing of the issue of phosphorus enrichment in animal manure and the environmental implications of such a phenomenon to foster the adoption of best management practices developed by EMBUL scientists to protect the quality and safety of our drinking and recreational water resources in the Chesapeake Bay Day event, October 5, 2005.

EMBUL scientists participated in USDA-Foreign Agricultural Service Research and Scientific Exchange Division Program effort by conducting sponsored scientific collaboration and information exchange with researchers in Vietnam to improve the understanding of the nutrition-environment linkage in animal agricultural systems of importance to Vietnam and the U.S. and the development of sustainable production practices for enhancing their adoption by livestock producers in both countries.


4d.Progress report.
Information is critically needed on the contribution of manure organic phosphorus such as phytic acid from feeds to the sources and sinks of dissolved phosphorus in the soil-manure-water system. Substantial amounts of organic phosphorus stored in feed grains are not available to the animal and are excreted in feces, contributing to water pollution rather than animal productivity. Where manure has been repeatedly land-applied, there is evidence that organic forms of phosphorus have moved through soils and contribute to the risks of water quality degradation via subsurface movement, in addition to overland discharges to streams, lakes, and estuaries. Speciation of organic phosphorus compounds in complex media such as animal wastewater, soil, and water environments is yet poorly understood. The knowledge gap hampers the understanding of the environmental behavior and transformations of inositol phosphates, in particular phytic acid in animal feed, manure, soil, water, and mixed environmental media thus the development of comprehensive strategies for mitigating agricultural phosphorus transfers to aquatic systems. Collection of bulk samples of field soils, manure, and P-immobilizing by-products have been conducted to initiate studies of organic P fractionation, characteristic spectra of major manure phosphorus forms, and soil, manure, and by-product incubations. Major efforts of project scientists will be expanded to address the issues raised in Objectives 1, 2, and 3 of the approved project.

In addition to the X-ray fluorescence method for non-destructively measuring phosphorus in dry cattle manure, poultry litter, feed, and soil samples, EMBUL scientist was making refinements to near- and mid-infrared reflectance spectroscopic measurements of P in manures (Objective 2b). Previous efforts have demonstrated that near-infrared reflectance spectroscopy can accurately determine both ammonium- and organic-N in manures, but regulations for such application are now being directed at P. As for N, P exists in both inorganic- and organic forms in dairy manures, the primary organic form being phytic acid. Preliminary efforts at determining P in dairy manures using near- and mid-infrared spectroscopy, and a variety of standard analytical measures of P, have not resulted in satisfactory calibrations for either organic- or inorganic-P despite the fact that such P compounds are known to absorb in the mid-infrared spectral range. One potential reason for this is the presence of cations in dairy manures (Ca, Fe, Na, etc.) from animal diets and other sources. The objective of this aspect of the research is to investigate the effects of cations on the spectral signatures of inorganic- and organic P and their potential impact on both spectral calibrations and conventional analytical methods for P in manures. Near-infrared spectra of phytic acid salts are relatively featureless when compared to their mid-infrared counterparts. However, in both cases, considerable spectral variation results from the interaction with different cations. With the many potential salts of phytic acid present in manures including mixed cation salts determining spectral signatures which can be used for calibration development may be difficult as conventionally carried out. Similar effects on conventional assay methods likely further complicate calibration development.

Incubation and fractionation experiments of manure P mineralization (Objectives 1c,.
4)were implemented. Incubation experiments with high P soils and s were also initiated (Objective 3b). Results from these studies will help farmers, by-product generators, and applicators know and predict the long-term environmental impact of utilizing these P-immobilizing by-products. Together, results of these incubation studies will assist researchers, nutrient management specialists, and farmers determine the release and availability of soluble phosphate from different manures and similar organic bioresources in soils to balance plant nutrients needs in varied crop production systems and minimize environmental discharges and impacts of potential losses.


5.Describe the major accomplishments to date and their predicted or actual impact.
Rapid analytical methods for P forms in complex mixed media were developed to bring about near-real time analysis capability. These achievements will enhance the feasibility of on-farm nutrient analyses. More precision can be achieved in determining land application matched to actual land carrying capacity for phosphorus as well as other mineral nutrients in manures.

Understanding of the chemical basis of the interactions between major forms of phosphorus, that is, phosphate and organic orthophosphate monoesters, and (i) polyvalent cations species in manures and soils, and (ii) other similarly negatively charged organic species in soil organic matter or soil amended with organic by-products proved to be critical factors explaining the results of studies of phosphorus distribution in soil aggregates and the potential loss of bioactive forms from conventional, no-till, and organic cropping systems utilizing manure as a plant nutrient source by scientists of the Sustainable Agricultural Systems Laboratory and EMBUL. Similarly, a collaborative effort between scientists of the Environmental Microbial Systems Laboratory scientists and EMBUL has greatly improved the understanding of the transport of manure indicator microorganisms by associating their transport characteristics to those of particulate organic bioactive P forms.


6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
During FY06, scientists of the Sustainable Agricultural Systems Laboratory, BARC adopted the bioactive phosphorus technology to evaluate carbon, nitrogen, and phosphorus distribution in soil aggregates and soil erodibility between no-till and tilled organic farming systems. This added critical information about the relative potential impacts of each farming practice on near-by aquatic environment.

EMBUL scientist communicated research results on the transformation of phytate and the distribution of different forms organic phosphorus associated with cations in manure and soils to scientists of EMBRAPA-Hortencia, Brasilia, Brazil in the role of organic P in phosphorus cycling in the development of no-till onions and tomato production systems. A collaborative MacroPrograma3 research proposal no-fund to ARS on the linkage of macronutrient cycling in such systems was developed and submitted for Brazilian funding consideration.

EMBUL scientist transferred bioactive phosphorus availability research to scientists of the Departamento de Agricultura, São Paulo State University, Botucatu, Brazil. Advised and adapted ligand-based enzyme-hydrolysable phosphorus assay to the determination of bioactive phosphorus in highly weathered Brazilian soils that are very low in plant-available phosphorus.

EMBUL scientist made invited presentation and followed up with a chapter of reference book on biochemical approach to elucidating behavior and fate of phosphorylated inositols in animal manure and the environment at the Bouyoucos Conference on “Inositol Phosphates in the Soil-Plant-Animal System” co-sponsored by Soil Science Society of America, ASA, and USDA-ARS, and presentations at the International conference on Plant Nutrition for Food Security, Human Health, and Environmental Protection, Beijing, China, and the 18th World Congress of Soil Science.

EMBUL scientist advised an environment-caring family resident of Walker, MO, on phosphate levels and confirmatory approaches to monitor phosphorus and potential eutrophication in the Schell lake/Osage River conservation areas. Continues technical support for that community.


7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below).
Chesapeake Bay Day Poster presentation entitled “Cutting Phosphorus Discharges into the Environment” (Oct. 5, 2005).


Review Publications
Dao, T.H., Codling, E.E., Schwartz, R.C. 2005. Time dependent phosphorus extractability in calcium- and iron-treated high-phosphorus soils. Soil Science. 170:810-821.

Green, V.S., Cavigelli, M.A., Dao, T.H., Flanagan, D.C. 2005. Soil physical properties and aggregate associated c, n, and p in organic and conventional cropping systems. Soil Science. 170:822-831

Dao, T.H. 2005. Ligand effects on phytic acid in animal manures. [abstract].Bouyoucos Conference Proceedings. p. 33.

Green, V.S., Dao, T.H., Cavigelli, M.A., Flanagan, D.C. 2005. Aggregate associated carbon, nitrogen, and phosphorus dynamics [abstract]. American Society of Agronomy Meetings [CDROM]. Poster No. 285-17

He, Z., Dao, T.H., Honeycutt, C.W. 2006. Insoluble fe-related inorganic and organic phosphates in animal manure and soil. Soil Science. 171:117-126

Green, V.S., Cavigelli, M.A., Dao, T.H., Flanagan, D.C. 2006. Soil and nutrient erosion risk in organic and conventional cropping systems. World Congress of Soil Science, July 9-15, 2006, Philadelphia, PA, No. 59-5 [CD-ROM].

Dao, T.H., Lugo-Ospina, A., Reeves Iii, J.B., Zhang, H. 2006. Wastewater chemistry and fractionation of bioactive phosphorus in dairy manure. Communications in Soil Science and Plant Analysis. 37:907-924.

Dao, T.H., Codling, E.E., Schwartz, R.C. 2006. Managing phosphorus-enriched soils: effects of iron amendment on temporal dynamics of bioactive phosphorus pools [abstract]. World Congress of Soil Science, July 9-15, 2006, Philadelphia, PA. No. 154-11 [CD-ROM].

Reeves Iii, J.B., Dao, T.H., Reeves, V.B. 2006. Investigations into the potential of near- and mid-infrared diffuse reflectance spectroscopy for determining p in dairy manures [abstract]. Proceedings of Pittcon Meeting. Paper No. 1220-4P.

Dao, T.H. 2005. Remediation of nutrient-enriched soils following repeated applications of animal manure. In: Proceedings of the Environmental Remediation Approaches to Municipal and Industrial Pollution in Vietnam Conference, October 25-26, 2005, Ho Chi Minh City, Vietnam. pp. 136-147.

Dao, T.H. 2005. Differentiating forms and potential bioactivity of environmental phosphorus. In: Proceedings of the Environmental Remediation Approaches to Municipal and Industrial Pollution in Vietnam Conference, October 25-26, 2005, Ho Chi Minh City, Vietnam. p. 148-156.

Last Modified: 4/17/2014
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