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United States Department of Agriculture

Agricultural Research Service

2007 Annual Report

1a.Objectives (from AD-416)
1. Identify the physical and chemical characteristics of manure and soil-manure interactions that influence phosphorus transformations to determine controlling mechanisms of phosphorus mobilization and bioactivity.

2. Develop rapid and accurate on-farm measurement tools to quantify bioactive phosphorus in manure and manure amended soils for managing whole-farm phosphorus balance.

3. Develop zeolitic materials and other by-products and novel methods for phosphorus immobilization, removal, and recovery from manure based on bioactive phosphorus chemistry and mechanisms of phosphorus mobilization.

4. Develop manure and soil parameters and module that links organic phosphorus transformations to the cycling of carbon and nitrogen to refine the Root Zone Water Quality model.

1b.Approach (from AD-416)
An integrated approach involving laboratory and field research and modeling will be used to improve the understanding of phosphorus transformations, mobilization, and fate to control its environmental losses. A comprehensive study of phosphorus mineralization in manure and manure-amended soils will be conducted. Improved quick tests by infrared spectroscopy and biological assays and modeling and decision-support tools, will be developed to evaluate effects of manure management practices on soil active and time-dependent phosphorus pools. Immobilization and recovery of phosphorus by zeolitic materials and evaluations of the potential re-solubilization of phosphorus that was immobilized using soil and manure additives will be made to add to whole-farm management options.

3.Progress Report
Two soils amended with water-treatment residuals were exposed to alternate wet-dry regimes for a period of six months. The treated soils are subsequently subject to flooding to induce anaerobic conditions or to the lowering of the soil pH to 4. Subsequently, Bermudagrass was planted in the low pH soils and rice was planted in the submerged soils in order to determine phosphorus availability to these crops. The rice plants are being harvested bimonthly while the Bermudagrass is harvested monthly.

Spectral signatures of various salts of phytic acid by diffuse-reflectance infra-red Fourier-transform spectroscopy greatly differ whether phytate occurs as salts of calcium, aluminum, iron, or sodium. The near IR spectra are nearly featureless and show slight differences between calcium-, aluminum-, and iron phytates. Meanwhile, differences in the various forms of phytate are apparent in the mid infra-red region around 3500 cm-1 and the absorbance region between 1700 and 700 cm-1. These spectral differences further complicate the application of infra-red spectroscopic techniques to quantify these organic phosphates in environmental samples. In all likelihood, mixtures of salts of exist in manure and soil. A continuous range of cation to phytate-phosphorus also exists to limit our success at using individual spectral signatures to resolve manure phosphorus composition.

A ten acre field of hybrid poplar trees was established in FY07 to study the trees’ ability to take up phosphorus from surface applied poultry litter. The litter is applied annually at half-, full-, and twice the recommended rate for poplar trees. Soil samples will be collected to 20 cm following litter application and yearly for the determination of soil extractable phosphorus content. Plant tissue samples will be collected yearly and at harvest (following seven years of growth) and analyzed for total phosphorus content. Ultimately, the trees are a marketable commodity while they attest to the beneficial reuse of manure nutrients in bioenergy feedstock production.

Rapid composition and screening of litter sources: A X-ray fluorescence method developed to measure phosphorus non-destructively was applied to determine the composition of a diverse set of 71 chicken litter from poultry-producing areas of NW Arkansas, Eastern Oklahoma, and the Eastern Shore of Maryland in the Delmarva region. Over 800 millions broilers are produced annually in the combined areas, and each bird generates close to 2000 lbs of dry litter/year. This litter varied widely in nutrient content as well as mineral dietary supplements such as arsenic and copper.

Current analytical methods are not conducive to rapid analysis of a large number of replicates of such heterogeneous materials. The variability undermines the accuracy of land application rates and optimal allocation of manure-borne constituents on the farm and on a watershed scale. Simultaneous multi-element analytical capabilities proved beneficial to determining phosphorus, other macronutrients as well as trace elements, and to categorizing of the litter sources as broiler or layer manures. Some of the samples were from farms producing laying hens. Calcium concentrations were three to four times higher in laying hen litter than other poultry litter samples because of calcium importance in eggshell quality. Broiler litter also contained higher concentration of arsenic (35.8 mg kg-1) than layer litter (1.9 mg kg-1). Twenty percent of the samples of this group had arsenic concentrations greater than 40 mg kg-1 which exceed the threshold limit for land application for arsenic in biosolids under 40CFR 503 rules. Similarly, feed ingredient analyses showed the enrichment of enzyme-labile phytate-phosphorus in the litter. The pool of enzyme-labile organic phosphorus form represents a sizable phosphate source under biological controls and contributes to the long-term supply and release of soluble phosphorus from poultry litter. Accurate measures of these stocks in manure are critical to determining the true risk of soluble phosphorus from specific manure. This research contributed directly to the Nutrient Management Component, Problem Area 3, Managing Tools for Indexing and Evaluating Nutrient Fate of National Program 206.

Extracellular phytases as biosensor for environmental organic phosphorus: Studies of induction and expression of phytases in selected fungal strains showed that growth and enzyme induction characteristics were significantly affected by the composition of the culture medium. Expression and specific activity of the enzyme isolates were similarly affected. Enzyme kinetic parameters have been determined to compare hydrolytic efficiency of the isolates. Enzyme stability and integrity of activity of purified isolates were observed across a wide range of feed ingredients and environmental specimens such as poultry manure and soils. BARC scientists collaborated with Vietnamese scientists to develop in-house isolates that were very effective at releasing phosphate-phosphorus from model phytate, or organic phosphorus in poultry litter, or field soils. The robustness of fungal phytases has been developed for detecting and quantifying forms of organic phosphorus in feed ingredients, manures, and other environmental specimens, based on an existing bioactive phosphorus assay developed by the Environmental Management ByProducts Utilization Laboratory scientist. This research contributed directly to the Nutrient Management Component, Problem Area 3, Managing Tools for Indexing and Evaluating Nutrient Fate of National Program 206.

Biological significance of unreactive phosphorus in runoff to improving the Phosphorus Site Vulnerability Index used to assess risks of offsite losses: While runoff contained soluble reactive and unreactive phosphorus forms, previous studies have not focused on the chemical nature and bioavailability of the many phosphorus-containing organic compounds that are included in the molybdate-unreactive phosphorus fraction. An asymmetrical log-normal distribution function was applied to describe the dynamics of various bioactive phosphorus forms in runoff from two forage-based systems under simulated rainfall. This study showed that bioactive forms were present in greater concentration and mass than water-soluble phosphorus in runoff and potentially, more phosphorus of the total phosphorus in runoff that were considered molybdate-reactive and unreactive phosphorus forms, was biologically available to increase the risk of agricultural runoff to freshwater systems. Soil amended with manure phosphorus and soil under the orchardgrass-red clover cover had the greatest phosphorus mass loss. The results suggested that the orchardgrass-clover system removed less phosphorus than the high-biomass producing forage-type soybean-winter wheat system. Runoff phosphorus forms were directly associated with soil available phosphorus fractions that involved enzyme-mediated processes, as indicated by the strength of correlations between cumulative mass losses of water-soluble phosphorus and soil bioactive phosphorus pools. The results also suggested that knowledge of the pattern of the asymmetrical pattern of release was an important factor because the characteristics of the loss process could be altered by management practices and production potentials of the forage systems. This research contributed directly to the Nutrient Management Component, Problem Area 3, Managing Tools for Indexing and Evaluating Nutrient Fate of National Program 206.

5.Significant Activities that Support Special Target Populations
During FY07, scientists of the Environmental Microbial Safety Laboratory at BARC adopted the bioactive phosphorus methodology to evaluate the release and transport of fecal coliform indicators and bioactive phosphorus forms in live and dead grass buffer strips. This added critical information about the relative potential impacts of each farming practice and the mitigation of the impacts of manure applications on near-by aquatic environments. This is particularly important to small organic farms employing animal manure as primary source of organically-based plant nutrients.

An EMBUL scientist made a symposium presentation at the 3rd International Conference on Enzyme in the Environment to describe the sensing or detection of phosphorus forms found in feed ingredients and the bioconcentration and enrichment of phosphorus in poultry manure. Stable and highly active phytases were needed to characterize the phosphorus profiles in highly diverse environmental specimens and the widely diverse soil-water environments researchers and organic farming operators encounter across the U.S. and other countries. Activities of phosphatases, as well as a whole suite of soil enzymes, are important indicators of soil fertility, nutrient bioavailability, and overall system health.

6.Technology Transfer

Number of non-peer reviewed presentations and proceedings5
Number of newspaper articles and other presentations for non-science audiences2

Review Publications
Dao, T.H. 2006. Ligand effects on phytic acid in animal manures: assessing time dependence of inositol phosphate solubilization and bioactivity. In: Turner, B.L., Richardson, A.E., Mullaney, E.J., editors. Inositol Phosphates: Linking Agriculture and Environment. CAB International, Oxfordshire, UK. p. 169-185.

Codling, E.E. 2006. Characterization of extractable phosphorus in poultry litter and poultry litter ash. Soil Science. 171:858-864.

Sadeghi, A.M., Graff, C.D., Starr, J.L., McCarty, G.W., Codling, E.E., Sefton, K.A. 2006. Spatial variability in phosphorus before and after poultry manure application in small plots. Soil Science. 171:850-857.

Green, V.S., Dao, T.H., Cavigelli, M.A., Flanagan, D.C. 2006. Phosphorus fractions and dynamics among soil aggregate size classes of organic and conventional cropping systems. Soil Science. 171:874-885.

Last Modified: 4/24/2014
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