1a. Objectives (from AD-416)
Evaluate the environmental risks and benefits from agricultural applications of agricultural and industrial byproducts (e.g., FGD-gypsum, compost/manure) including uses to remediate disturbed soils and to sequester and phytoremediate metal from metal contaminated soils. Develop new, innovative, value-added products from agricultural and industrial byproducts (e.g., poultry feathers), and evaluate their suitability for their proposed end uses.
1b. Approach (from AD-416)
Develop and/or modify existing analytical methods to evaluate physical and chemical properties of byproducts and the potential environmental risks and benefits from their use in agriculture. Characterize mercury (Hg) emissions from FGD-gypsum amended soils. Evaluate plant species recommended for phytoextraction of Cd from U.S. contaminated soils requiring remediation to protect food safety. Determine physical and chemical properties of agricultural byproducts (e.g., poultry feathers, bone meal, egg shell waste, corn stalk, and cobs.
3. Progress Report
Although industrial, municipal and agricultural byproducts have been used in agriculture for many years, there is a need to identify and determine potential benefits/risks in using these byproducts in agriculture. Byproducts and value added materials made from byproducts were collected and evaluated in both laboratory and field studies to determine their effects on sequestering and remediating cadmium, nickel and lead contaminated soils. Data collected from these studies are being used in developing risk assessment of these byproducts. There is a growing interest in urban gardening. However, many urban vegetable gardens are planted on inner city lots or around homes with high lead levels from lead paint use. Inexpensive byproducts, that urban home owners can have easy access to, were evaluated. Some byproducts were very effective in reducing lead uptake by root and leafy vegetable crops. Significant progress was made in producing and evaluating value added products such as pots made from poultry feather fiber to be used in horticulture. Presently, chicken feather fiber pots are being made commercially for the horticultural industry.
1. Develop new, value added products from industrial byproducts (coal ash). As a result of the Oklahoma City bombing of the Alfred P. Murrah Federal Building in downtown Oklahoma City on April 19, 1995, new regulations on licensing, sale and shipping of ammonium nitrates were developed to reduce a possible repeat of the Oklahoma bombing. Research is also being conducted to reduce the explosive effects of ammonium nitrate by encapsulating ammonium nitrate with byproducts such as fly ash and flue gas desulferization gypsum that are produced from electrical power plants to reduce explosive effects of ammonium nitrate. Research by an ARS scientist at Beltsville, Maryland, has demonstrated in greenhouse and field studies, that encapsulated ammonium nitrate was as effective as un-encapsulated ammonium nitrate for crop production, without metal in soil and plants from the byproducts.
2. Develop new, innovative value added products from agricultural byproducts (poultry feathers). An ARS scientist developed and tested three commercially viable pellets and horticultural flower pots made from bioresin. In a greenhouse study, bioresin formulations were designed to be effective for at least 6 months. In addition, some formulations enhance plant growth during this period.
3. Revegetation of barren asbestos emmiting superfund site using compost and gypsum. The Vermont Asbestos Group Superfund site is 300 acres of barren ground serpentinite rock which has remained barren for over 50 years due to severe infertility and poor soil properties. Methods to achieve persistent revegetation of such sites are being tested in cooperation with the U.S.-Environmental Protection Agency and the Vermont Department of Environmental Conservation. Based on previous success, using composts and biosolids in remediation of metal toxic soils, revegetation mixtures were designed and tested to alleviate both infertility and toxicity of the site soils with grasses and legumes. Mixtures of manure composts with flue gas desulferization(FGD)-gypsum and nitrogen phosphorus potassium(NPK) gave immediate and strong revegetation in a greenhouse pot trial with potential cover crops. Two available commercial composts in northern Vermont were mixed with gypsum, NPK and limestone for a field test of revegetation during August 2010, and extensive vegetative cover was obtained and is persistent. Alternative treatment by leveling and cover with 24 inches of topsoil was estimated to cost $200 million, while use of surface applied compost mixtures should cost no more than $1.5 million and use locally available resources without removing topsoil from other locations.
4. Zinc (Zn) toxicity to forest spreading near closed zinc smelter in Palmerton, Pennsylvania. Severe zinc phytotoxicity killed over 1000 acres of forest near a Zn smelter at Palmerton, PA, which closed in 1980. Where soil amendments were used, effective revegetation has persisted and become more diverse. However, where no remediation activities have taken place, extreme soil acidity has slowly become worse due to acidic rainfall. Investigations were undertaken to evaluate understory vegetation in remaining forest on the south side of Blue Mountain. Based on analysis of soils and plants, and measurement of seedlings present, it is clear that soil toxicity is preventing establishment of all plant species under existing remaining trees. Plant analysis shows that both zinc and manganese emitted by the smelter are contributing to toxicity and death of seedlings. Remediation tests using limestone and fertilizer show that the persistent toxicity of these extremely acidic soils can be reversed by raising soil pH. But in the absence of human action, continuing acidic rainfall will likely cause increase in the barren area due to metal toxicity.
5. Phyto-ruminal bioremediation of soil tri nitro toluene (TNT). Explosive contaminated soils comprise environmental risk and require remediation. The ability of plants to bioremediate and phytoextract soil TNT was evaluated in greenhouse tests with 14C-labeled TNT and three grass species. Plant roots and soil microbes caused extensive conversion of soil TNT into covalently linked bound residue in the soil or in plant roots, while repeated plant harvests found significant amounts of 14C from the TNT in plants shoots over the year study. No free TNT remained in soil or plants showing the ability of soil and plants to achieve remediation of soil TNT risks. The plant uptake research is linked to studies in which TNT was fed to sheep to evaluate metabolism of TNT by rumen organisms. Together the phytoremediation and ruminal-bioremediation are highly effective in reducing environmental risk from soil TNT.
6. Beneficial use of zinc (Zn) from ground rubber tires. Waste tires are a significant environmental problem; some tires are used to produce energy and others to produce ground rubber to mix with soil to reduce physical compaction in high traffic areas. Because tire rubber contains about 1.5% Zn and highly purified Zn (very low in cadmium and lead) is used in the vulcanization of rubber, we tested use of ground rubber as a Zn fertilizer and as a potting medium component. One study tested the kinetics of release of Zn from ground rubber compared to standard Zn fertilizers; rubber served as a slow release source of Zn which kept plant Zn higher than did Zn sulfate. Zn salts added to soils can be rapidly transformed to unavailable Zn minerals, while the slow release of the inexpensive recycled ground rubber as Zn fertilizer can correct Zn deficiency for many years. Previous studies of using ground rubber in potting media for flowers and vegetable transplants found Zn toxicity often occurred; the use of nitric acid to remove the more soluble Zn from ground rubber produced a potting medium ingredient which no longer caused Zn phytotoxicity for tomatoes and actually improved yields compared to standard media. And Zn washed from rubber by acid could be used as Zn fertilizer in calcareous soils. Taken together, waste ground rubber may be a valuable Zn fertilizer for Zn deficient soils, and acid wasted ground rubber may be a useful potting medium ingredient. A field test using ash from burning ground rubber showed effective Zn fertilizer response by Zn-deficient wheat which caused a significant reduction in cadmium in wheat grain. In a separate test of using ground rubber as Zn fertilizer, durum wheat plots were treated with Zn sulfate and ground rubber in AZ to learn if Zn fertilization could reduce grain cadmium levels. Wheat yield was not affected in these soils which were not Zn-deficient. Grain cadmium remains to be measured.
7. Chemical species of nickel (Ni) in xylem exudate of alyssum corsicum. Using the Ni hyperaccumulator plant Alyssum corsicum to phytoextract Ni from mineralized or contaminated soils offers a commercial alternative to traditional mining, but using agricultural technologies. Improved understanding of how these plants achieve such remarkable accumulation and transport of Ni from soil to leaves is expected to aid in improving this technology or allow eventual transfer of all needed genes to higher yielding crop plants. Earlier published work suggested that Ni being translocated to plant shoots in the xylem fluid was predominantly chelated by histidine, but this was based on short term studies and only solution grown plants. Several Ni hyperaccumulator Alyssum species were grown in nutrient solutions or in serpentine soils for six weeks before the stem was cut and xylem exudate collected for 1 hour. Modern analytical methods allowed reliable detection of organic and amino acids under steady state hyperaccumulating conditions. Exudate Ni was commonly 3 millimolar, while histidine, citric acid, malic acid and nicotianamine, the amino and organic acids previously reported to possibly be the important chelator of Ni in these plants were typically no more than 0.10 millimolar, showing that Ni in xylem exudate is mostly not chelated but moves as a free cation. These findings support other research which suggests that the free cation is the material transferred across plant membranes by protein transporters. Similar results were found for six Alyssum hyperaccumulator species, and for both solution and soil grown plants, clearly contradicting previous reports on this topic.
8. Beneficial use of nickel (Ni) hyperaccumulator plant as a nickel fertilizer. Research by ARS pecan nutritionists showed severe Ni deficiency has occurred in pecans in the U.S., and Ni sulfate is marketed as a Ni fertilizer. Research was conducted to evaluate the use of Ni extracted by Alyssum Ni hyperaccumulator biomass as an alternative Ni fertilizer. The Alyssum extract was just as effective as the Ni sulfate chemical, and could be produced at far lower cost. This use of Ni salt and Alyssum extract or biomass is the subject of an Australian patent issued in 2010. Use of ground biomass to fertilize pecan and other crops which respond to fertilizer Ni could become an organic farming practice.
9. Reducing bioavailability of soil dichloro diphenyl trichloroethane (DDT) to earthworms using compost and plants. Old orchards and other land may contain excessive residues of DDT and dichloro diphenyldichloro ethylene (DDE) from historic pesticide sprays. Because earthworms bioaccumulate DDE from soils, and some birds and small mammals ingest large amounts of earthworms, the most limiting risk pathway for soil DDE is earthworm bioaccumulation to harm wildlife. Old orchard soils at BARC contain sufficient DDE to require removal or other remediation at great expense, and a in situ remediation test was funded. Soil samples were collected from the field to locate soil with levels of DDE (10 mg/kg dry soil) which would make a more useful test of DDE risk remediation using organic amendments and plants. Experiments were planned to test whether incorporation of composted manure, composted biosolids, biochar, etc., could reduce DDE bioaccumulation by earthworms by increasing the strength of adsorption of DDE by the amended soils, and to better understand the mechanism of remediation.
10. Phytoextraction of cadmium (Cd) from soils containing excessive biosolids applied Cd. Before modern regulations of biosolids utilization were established, some biosolids with high concentrations of Cd and other elements were land applied at some cities. And very high cumulative applications of biosolids had been made at some locations. Growing of non-food crops prevents risk from such high Cd soils, but limits return on the investment in now contaminated land. Excessive Cd in some soils requires remediation before alternative land use may be permitted. Thus a test of phytoextraction of Cd from soils from the Metropolitan Water Reclamation of Greater Chicago was cooperatively initiated. Our previous tests of Thlaspi caerulescens for Cd phytoextraction showed some success with similar soils, and Japanese research suggested that unusual Cd accumulating rice cultivars may be useful in Cd phytoextraction. In addition, newly identified Chinese Cd hyperaccumulator herbaceous species were obtained for testing. Soils from long term biosolids application fields from Fulton County, IL, were provided and prepared for growing the test plants. Soil pH was adjusted to lower and higher pH than as received to test both plant tolerance and metal accumulation from these soils. We attempted to grow the rice under aerobic conditions to maximize Cd accumulation compared to normal flooded culture which limits Cd uptake. Many rice genotypes did not tolerate the high levels of biosolids-applied metals in the soil. Analysis of plant materials from the tests is in progress.
11. Using compost plus byproduct "biomats" to remove contaminations from runoff. Previous laboratory tests showed that a mixture of manure compost plus steel mill slag and sand was a very effective filter to remove phosphorus, cadmium and zinc from runoff waters from an Animal Plant Health Inspection Service (APHIS) building with lead exterior walls. New funding was supplied to install a field scale test of the technology at the APHIS building at BARC. The filters were designed based on the laboratory experiment results and physical circumstances at the building and parking lot where the tests will be conducted. The experimental filters and water collection equipment are presently being installed and will be studied during 6 months of storm events to examine the removal of contaminants from runoff from the building and a large parking lot. Runoff from both locations presently exceeds standards for discharge to surface waters of Maryland.
12. Risk assessment for beneficial use of flue gas desulferization (FGD)-gypsum in agriculture. ARS researchers and others have been conducting research to evaluate the beneficial use of FGD-gypsum in agriculture. Ultimately, the adoption of FGD-gypsum use will depend on “Beneficial Use Designation” at the State level. ARS is cooperating with the US-Environmental Protection Agency in conducting a full risk evaluation of this use to provide information needed at the State level to make regulatory decisions about FGD-Gypsum use as fertilizer and soil conditioner. The electrical generating industry which manufactures FGD-gypsum, while removing sulphur dioxide (SO2) from exhaust gases, has changed their exhaust treatment systems to remove fly ash before removing SO2, allowing the production of FGD-gypsum with very low levels of trace elements compared to earlier products, confirmed by analysis. Field tests have been being conducted to assess the ability of FGD-gypsum to reduce the runoff of phosphate from soils including soils amended with poultry litter on the surface of hay fields. To date, research has shown that application of FGD-gypsum can significantly reduce runoff phosphorus (P) and arsenic (As). One potential adverse effect was identified in which grazing ruminants may ingest significant amounts of FGD-gypsum from field storage piles if they are not fenced. Excessive sulfate intake by ruminants can cause harm, but is easily prevented by preventing access to piles of gypsum. Other research has not found adverse effects of soils amended with FGD-gypsum compared to unamended soils.
Duringer, J.M., Craig, A.M., Smith, D.J., Chaney, R.L. 2010. Uptake and transformation of soil [14C]-trinitrotoluene by cool-season grasses. Environmental Science and Technology. 44:6325-6330.