Chemical Amendments Research Articles

Phosphorus Immobilization and Soil Aggregation in Chemically Amended Poultry Litter Used in Corn/Soybean Rotation

Excessive use of poultry litter (PL) on agricultural land is known to cause eutrophication of surface waters. Consequently, both poultry producers and PL users have to meet strict state and federal guidelines on litter storage and land application. This study examined the environmental benefits of adding lime, alum, ferrous sulfate, fly ash (FA), fluidized bed ash (FBA) and soil fix (SF) to PL for immobilizing excess phosphorus (P) while providing sufficient nutrients for proper growth of soybean [Glycine max (L.)] and corn [Zea mays (L.)] on a rotation. Amending PL with lime, alum, SF, FA and FBA significantly (p>0.05) increased corn and soybean yield. In contrast control plots that received a 10-10-10 (N-P2O5-K2) fertilizer showed lower yield and corn quality. Increased yield was observed when PL was amended with lime, alum and ferrous sulfate. Results from a soybean root, shoot, and nodule growth study indicated variability with respect to PL application and amendment use. Smaller size nodules were obtained with NPK fertilizer and PL plus lime treated plots, whereas PL with alum yielded fewer but larger nodules. Soil aggregation was significantly lower in soils treated with NPK compared to those treated with PL as indicated by water stable aggregation (WSA), mean aggregate diameter (MWD) and geometric mean of aggregate diameter (GMD) (p>0.05). Increased soil aggregation was a result of the combined effect of amendment and PL additions rather than PL alone. The amount of carbon (C) in soil aggregates was lowest with NPK and highest with PL treatments. In the presence of PL, alum and iron treatments showed higher capacities to store C and immobilize P in macro-aggregates (8 to 5 mm diameter). These results suggest that soil treatment with PL and chemical amendments, especially alum and ferrous sulfate, could result in improved crop yield, soil aggregation, carbon storage, and P immobilization.

Phosphorous Cycling in the Greater Everglades Ecosystem: Legacy Phosphorous Implications for Management and Restoration

Phosphorus (P) retention in wetlands is an important function of watershed nutrient cycling, particularly in drainage basins with significant nonpoint nutrient contributions from agriculture and urban sources. Phosphorus storage involves complex interrelated physical, chemical, and biological processes that ultimately retain P in organic and inorganic forms. Both short-term storage of P mediated by assimilation into vegetation, translocation within above- and below-ground plant tissues, microorganisms, periphyton, and detritus, and long-term storage (retention by inorganic and organic soil particles and net accretion of organic matter) need to be considered. Here, we review and synthesize recent studies on P cycling and storage in soils and sediments throughout the Greater Everglades Ecosystem and the influence of biotic and abiotic regulation of P reactivity and mobility as related to restoration activities in south Florida. Total P storage in the floc/detrital layer and surface soils (0–10 cm) is estimated to be 400,000 metric tons (mt) within the entire Greater Everglades Ecosystem, of which 40% is present in the Lake Okeechobee Basin (LOB), 11% in sediments of Upper Chain of Lakes, Lake Istokpoga, and Lake Okeechobee, 30% in the Everglades Agricultural Area (EAA), and 19% in the Stormwater Treatment Areas (STAs) and the Everglades. Approximately, 35% of the P stored is in chemically nonreactive (not extractable after sequential extraction with acid or alkali) pool and is assumed to be stable. Phosphorus leakage rates from LOB and EAA are approximately 500 and 170 mt P per year, respectively, based on long-term P discharges into adjacent ecosystems. The estimated reactive P in the LOB soils is 65% of the total P, of which only 10 –25% is assumed to leak out of the system. Under this scenario, legacy P in LOB would maintain P loads of 500 mt per year to the lake for the next 20– 50 years. Similarly, surface soils of the EAA are estimated to release approximately 170 mt P per year for the next 50–120 years. The role of the STAs in reducing loads to downstream regions is critical and requires effective management of P forms to ensure the P is stabilized in these systems by the addition of chemical amendments or by dredging of accumulated soils. Also, additional efforts to minimize leakage of the legacy P from the northern regions should also be evaluated to reduce external P loading loads to the STAs.

Effects of Amendments on Copper, Cadmium, and Lead Phytoextraction by Lolium Perenne from Multiple-Metal Contaminated Solution

Chemical amendments can increase metal uptake by plant roots and translocation to shoots, however their effectiveness can be influenced by the presence of other amendments and metal ions in a multiple-metal environment. A range of amendments and combinations were tested to explore their effect on phytoextraction of Cu, Cd, and Pb by perennial ryegrass (Lolium perenne) from solutions containing one or more of these metals. The amendments studied included EDDS (an aminopolycarboxylic acid), histidine (an amino acid), citric acid (an organic acid), rhamnolipid (a biosurfactant) and sulfate (an inorganic ligand). For all amendment treatments, the presence of multiple metals in solution reduced shoot concentrations of Cd and Cu, while Pb levels in shoots were generally enhanced by the presence of Cu. Although slightly toxic to the plants, EDDS (1 mM) was the most effective individual amendment for enhancing shoot metal uptake and translocation from solution without significantly reducing biomass yield. The combination Rhm+Cit+EDDS resulted in the highest shoot metal concentrations of all the treatments but also caused severe phytotoxicity. Amendment combinations Rhm+His and Sulf+Cit were less toxic for plant growth while moderately enhancing metal mass accumulation in shoots and thus could be considered as alternative treatments for enhanced phytoextraction.

Influence of amendments on soil structure and soil loss under simulated rainfall China's loess plateau

Macromolecule polymers are significant types of chemical amendments because of their special structure, useful functions and low cost. Macromolecule polymers as soil amendment provide new territory for studying China’s agricultural practices and for soil and water conservation, because polymers have the ability to improve soil structure, increase rainfall penetration and control slope runoff. Through indoor laboratory experiments and outdoor artificial rainfall simulations, this study applied different consistencies of three amendments; polypropylene acid (PPA), polythene alcoholic (PTA) and urea-formaldehyde poly-condensate (UR) to China’s Loess and determined their effects on soil physical properties and on runoff-sediment yield. The results indicate that as a result of applying the amendments, (1) the water-stable soil aggregates content increases by 17.3%, the soil permeability increases by 41.8%, the soil density decreases by 11.2% and the soil water content increases by 28.0% compared to the control; (2) three amendment applied on sloping land can delay runoff and decrease runoff velocity; decrease erosive forces of raindrop impact and flowing water, reduce surface crusting and improve water infiltration, delay runoff engenderation and decrease runnoff velocity and soil erosion yield. Finally, this study also ascertained optimal application quantities and the most effective sort in three amendments, which PPA is most effective at lowering surface runoff, reducing soil loss and increasing soil penetration. These three amendments have broad potential for soil and water conservation; however, the duration of their effect and the optimal application quantities need to be researched further. Key words : Amendment, Runoff-Sediment Yield, Soil Physical Properties, Soil erosion

Chemical treatments for mobilizing arsenic from contaminated aquifer solids to accelerate remediation

Arsenic is a prevalent contaminant at US Superfund sites where remediation by pump and treat systems is often complicated by slow desorption of As from Fe and Al (hydr)oxides in aquifer solids. Chemical amendments that either compete with As for sorption sites or dissolve Fe and Al (hydr)oxides can increase As mobility and improve pump and treat remediation efficiency. The goal of this work was to determine optimal amendments for improving pump and treat at As contaminated sites such as the Vineland Chemical Co. Superfund site in southern New Jersey. Extraction and column experiments were performed using As contaminated aquifer solids (81 ± 1 mg/kg), site groundwater, and either phosphate (NaH(2)PO(4)·H(2)O) or oxalic acid (C(2)H(2)O(4)·2H(2)O). In extraction experiments, phosphate mobilized between 11% and 94% of As from the aquifer solids depending on phosphate concentration and extraction time (1 mM-1 M; 1-24 h) and oxalic acid mobilized between 38 and 102% depending on oxalic acid concentration and extraction time (1-400 mM; 1-24 h). In column experiments, phosphate additions induced more As mobilization in the first few pore volumes but oxalic acid was more effective at mobilizing As overall and at lower amendment concentrations. At the end of the laboratory column experiments, 48% of As had been mobilized from the aquifer sediments with 100 mM phosphate and 88% had been mobilized with 10 mM oxalic acid compared with 5% with ambient groundwater alone. Furthermore, simple extrapolations based on pore volumes suggest that chemical treatments could lower the time necessary for clean up at the Vineland site from 600 a with ambient groundwater alone to potentially as little as 4 a with 10 mM oxalic acid.

Influence of Agricultural Practices on the Stability of Organo-Al Complexes in an Alu-Andic Andosol

The influence of agricultural practices on the stability of organo-Al complexes in alu-andic andosols was investigated in a 16-week experiment. Soil samples from an A horizon of a Typic Fulvudand were placed in filtration funnels and subjected to (i) liming (L), (ii) fertilization ([F] 700 kg ha1 N, 422 kg ha1 P2O5), and (iii) a combination of L + F. The amendments were added at time 0 and at the start of Week 8. All soils were subjected to simulated tilling (T) once a week. Controls with and without tillage were also established (T and Ctrl, respectively). A subset of samples from each treatment was also subjected weekly to heat treatment at 40°C (H), with the subsequent drying effect. All soils were watered 3 days each week, and leachates were collected After 16 weeks, a significant (P < 0.05) degree of acidification was observed both in the soils without chemical amendment (Ctrl, T, and T + H) and in the fertilized soils (pH <4.6). Acidification was accompanied by a flush of Al into solution. Heated soils had a large decrease in LaCl3-and CuCl2-extractable Al, especially in the soils that underwent all treatments (T + F + L + H). This was paralleled by an increase in dissolved organic C and Al released into solution and an increase in soil pH. The wetting and drying cycling induced by the heat treatment followed by irrigation may have promoted the effects observed, although other factors cannot be discarded. The findings showed how the loss of andic soil properties after land-use change occurs as a result of the combination of the different agricultural practices investigated, with heat and moisture fluctuations being the most important factors. Copyright © 2010 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.

The addition of chemical amendments to dairy cattle slurry for the control of phosphorus (P) in runoff from grasslands

The addition of chemical amendments to dairy cattle slurry for the control of phosphorus (P) in runoff from grasslands

Coupling indigenous biostimulation and phytoremediation for the restoration of 2,4,6-trinitrotoluene-contaminated sites

In-situ bioremediation has been highly promising in degrading nitroaromatics in soil, e.g., 2,4,6-trinitrotoluene (TNT). The case of TNT is examined here as a representative nitroaromatic compound that belongs to a suite of explosive residue types scattered throughout the European Union and other areas of the world. Differences in cost-effectiveness and TNT degradation rates between existing methods have spurred extensive debate in bioremediation research of explosive-contaminated sites. Rhizoremediation (plant inoculation with a specific microorganism), including genetic modification of plant/tree species, has been treated as the next best remediation method due to excellent performance in the lab. However, recent data collected in the field do not support the initial enthusiasm, showing in many cases, no statistical difference between (non-)transgenic rhizoremediation and phytoremediation (use of wild plant types). Obviously, the role of indigenous rhizospheric microorganisms has been underestimated, impeding our progress towards identifying the critical components of the optimum bioremediation scheme. Future research directions to enhance the indigenous microbial activity in the plant rhizosphere via addition of chemical amendments, such as, nutrients (fertilizers), and/or chaotropic agents (urea) could improve the overall efficiency of existing phytoremediation schemes.

Effects of sodic water on soil sodicity and nutrient leaching in poultry and sheep manure amended soils

The need to use saline and sodic waters for irrigating agricultural lands has increased due to a shortage of fresh water resources, especially in arid and semi-arid regions. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments. In this study, the effects of two organic fertilizers (poultry and sheep manure), and gypsum were evaluated in soil that received sodic water. These materials were added to a sandy loam soil at the rate of 5%, after which the treated soils and a control sample were incubated for one month at field capacity at 25–30 °C. Column leaching experiments using treated soils were then conducted under saturated conditions using two types of NaCl–CaCl 2 solutions and three sodium adsorption ratios (SAR) (0, 10, 40) with a constant ionic strength (50 mmol l − 1 ). The results indicated that the application of sheep and poultry manure to soils caused an increase in cation exchange capacity (CEC) and greater adsorption of cations such as calcium, magnesium and potassium than sodium (Na +). Conversely, the addition of organic amendments led to increased Na + leaching and a lower exchangeable sodium percentage (ESP). The ESP of the control soil after leaching with solutions with SAR of 10 and 40 increased significantly, but the level of sodification in treated soils was lower. The ESP of the poultry and sheep manures treated soils after leaching with solution with SAR 40 was significantly lower than control soil. Specifically, the rate of soil sodification in the treated soils declined in the following order: control soil > sheep manure treated soil > poultry manure treated soil > gypsum treated soil. Finally, the effects of gypsum on the sodification of soil by SAR 10 solution were the same as the effects of poultry manure, whereas the loss of cations and anions from poultry and sheep manure treated soils was greater than the loss from gypsum treated and control soils.

Amendments and their combined application for enhanced copper, cadmium, lead uptake by Lolium perenne

Chemical amendments can enhance heavy metal phytoextraction by increasing metal bioavailability for plant root uptake and translocation to shoots, and by improving plant growth. This study assessed the effect of various amendments on plant growth and metal uptake over a 30-day period. An aminopolycarboxylic acid (EDDS), amino acid (histidine), organic acid (citric acid), biosurfactant (rhamnolipid), and inorganic ligand (sulfate) were applied as amendments individually or in combination to hydroponically grown ryegrass (Lolium perenne cv. SR4500) in the presence of a metal (Cu, Cd or Pb). EDDS (1 mM) was the most effective amendment (individually and in combinations) for enhancing Cu and Pb uptake to shoot tissue, while histidine was beneficial for increasing both Cu and Cd uptake. Individual treatments of citric acid, rhamnolipid and sulfate moderately enhanced shoot concentrations of Cu and Cd only. The combination of EDDS, rhamnolipid and citric acid resulted in the highest shoot metal levels, but also caused severe phytotoxicity. Translocation to shoot tissue was generally greater for amendments with higher affinity for the metal of interest, and metal mobility appeared to be influenced by speciation. Due to potential toxicity, amendment combinations may be more effective when applied shortly before harvesting.

Field‐Scale Cleanup of Atrazine and Cyanazine Contaminated Soil with a Combined Chemical‐Biological Approach

A former agrichemical dealership in western Nebraska was suspected of having contaminated soil. Our objective was to characterize and remediate the contaminated site by a combined chemical-biological approach. This was accomplished by creating contour maps of the on-site contamination, placing the top 60 cm of contaminated soil in windrows and mixing with a mechanical high-speed mixer. Homogenized soil containing both atrazine [6-chloro-N-ethyl-N'-isopropyl-1,3,5-triazine-2,4-diamine] and cyanazine {2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl] amino]-2-methylpropanenitrile} was then used in laboratory investigations to determine optimum treatments for pesticide destruction. Iron suspension experiments verified that zerovalent iron (Fe(0)) plus ferrous sulfate (FeSO(4).7H(2)O) removed more than 90% of both atrazine and cyanazine within 14 d. Liquid chromatography/mass spectrometry (LC/MS) analysis of the atrazine solution after treating with Fe(0) and ferrous sulfate identified several degradation products commonly associated with biodegradation (i.e., deethlyatrazine (DEA), deisopropylatrazine (DIA), hydroxyatrazine (HA), and ammelines). Biological treatment evaluated emulsified soybean [Glycine max (L.) Merr.] oil (EOS) as a carbon source to stimulate biodegradation in static soil microcosms. Combining emulsified soybean oil with the chemical amendments resulted in higher destruction efficiencies (80-85%) and reduced the percentage of FeSO(4) needed. This chemical-biological treatment (Fe(0) + FeSO(4) + EOS, EOS Remediation, Raleigh, NC) was then applied with water to 275 m(3) of contaminated soil in the field. Windrows were tightly covered with clear plastic to increase soil temperature and maintain soil water content. Temporal sampling (0-342 d) revealed atrazine and cyanazine concentrations decreased by 79 to 91%. These results provide evidence that a combined chemical-biological approach can be used for on-site, field-scale treatment of pesticide-contaminated soil.

한우액상분뇨에 화학제재를 첨가 시 인과 총 휘발성지방산 함량에 미치는 영향

The objectives of this study were to evaluate the effects of chemical additives on total phosphorus (TP), soluble reactive phosphorus (SRP), and total volatile fatty acids (total VFAs) in hanwoo slurry. The treatments in this study were ferrous sulfate, alum, and aluminum chloride, and applied at the rate of 0, 0.5, and 1.0 g/25 g of hanwoo slurry. All of the chemical treatments significantly lowered TP (11 to 53% of the untreated control), SRP (41 to 99.9% of the untreated control), and total VFAs (22 to 48.5% of the untreated control) by reducing hanwoo slurry pH (3.42 to 6.86). Among these chemical amendments, addition of 0.5 g ferrous sulfate, alum, and aluminum chloride to hanwoo slurry were the best results evaluated on farms with respect to reducing negative environmental impacts. In conclusion, the results of this study indicate that the use of chemical amendments should be considered in the development of best management practices (BMPs) for the hanwoo industries.

Impacts of Chemical Amendment and Plant Growth on Lead Speciation and Enzyme Activities in a Shooting Range Soil: An X‐ray Absorption Fine Structure Investigation

In situ chemical immobilization is a practical remediation technology for metal-contaminated soils because of its capability to reduce cost and environmental impacts. We assessed the immobilization effects of poultry waste amendment and plant growth (Panicum maximum Jacq.) on Pb speciation and enzyme activities in shooting range soils. Soil contaminated with Pb was obtained from the top 20 cm of a shooting range. To evaluate Pb mobility in the soil profile treated with plants and immobilizing amendment, we used large columns filled with Pb-contaminated soil (0-20 cm, surface soils) and non-contaminated soil (20-75 cm, subsurface soils). The column study demonstrated that the amendment reduced the toxicity characteristic leaching procedure-extractable Pb in the surface soil by 90% of the Control soil. Lead mobility from the surface to subsurface profiles was significantly attenuated by plant growth but was promoted by the amendment without plant application. The extended X-ray absorption fine structure analysis revealed that the amendment reduced the proportion of PbCO(3) and Pb-organic complexes and transformed them into a more geochemically stable species of Pb(5)(PO(4))(3)Cl with 30 to 35% of the total Pb species. Applications of plant and amendment increased activities of dehydrogenase and phosphatase in the surface soil with 2.7- and 1.1-fold greater than those in Control, respectively. The use of amendments in combination with plant growth may have potential as an integrated remediation strategy that enables Pb immobilization and soil biological restoration in shooting range soils.

Silicate fertilization in no-tillage rice farming for mitigation of methane emission and increasing rice productivity

Agricultural practices mostly influence methane (CH4) emissions from rice field, which must be controlled for maintaining the ecosystem balance. No-tillage farming with chemical amendments having electron acceptors could be an effective mitigation strategy in CH4 emissions from irrigated rice (Oryza sativa L.) field. An experiment was conducted in Korean paddy field under tillage and no-tillage farming practices with silicate iron slag amendments (1–4Mgha−1) for suppressing CH4 emissions and maintaining rice productivity. It was found that CH4 emissions from the no-tillage rice field significantly decreased as compared to that of tilled field, irrespective of silicate amendments. The total seasonal CH4 flux from the control tillage and control no-tillage plots were recorded 38.1 and 27.9gm−2, respectively, which were decreased by 20% and 36% with 4Mgha−1 silicate amendment. Silicate fertilization (4Mgha−1) with no-tillage system decreased total seasonal CH4 flux by 54% as compared to that of control tillage plot. This is most likely due to the higher concentrations of active iron and free iron oxides in the no-tilled rice field as compared to that of tilled field under silicate fertilization, which acted as electron acceptors and contributed to decrease CH4 emission. In addition, the improved soil porosity and redox potential, rice plant growth parameters such as active tillering rate, root volume and porosity, etc. in combination increased the rhizosphere oxygen concentrations and eventually suppressed CH4 emission during the rice growing season. The leaf photosynthetic rate was significantly increased with 4Mgha−1 silicate amendment, which ultimately increased grain yield by 18% and 13% in the tilled and no-tilled rice field, respectively. CH4 flux showed a strong positive correlation with the availability of soil organic carbon, while there were negative correlations with soil porosity, soil pH, soil Eh, and the content of active iron and free iron oxides in soil.

Effects of Soil Amendments on the Extractability and Speciation of Cadmium, Lead, and Copper in a Contaminated Soil

The effects of chemical amendments including zeolite, compost and mesoporous molecular sieves (MCM-41) on the extractability and speciation of heavy metals (Cd, Pb and Cu) in a contaminated soil were investigated. Results showed that the application of soil amendments decreased Cd, Pb and Cu uptake by the shoots of pakchoi, up to 44.2-53.2%, 30.2-42.7% and 16.9-22.1%, respectively, compared with the control. Among the three amendments, zeolite and MCM-41 were more efficient in reducing Cd and Cu uptake, while compost was more efficient in reducing Pb uptake by the plants. The growth of pakchoi was improved in amended soils due to the action of chemical amendments.

Alternative amendment for soluble phosphorus removal from poultry litter

Alum (aluminum sulfate) is the currently preferred chemical amendment for phosphorus (P) treatment in poultry litter (PL). Aluminum-based drinking-water treatment residuals (Al-WTRs) are the waste by-product of the drinking-water treatment process and have been effectively used to remove P from aqueous solutions, but their effectiveness in PL water extracts has not been studied in detail. Elevated cost associated with alum could be minimized by using the equally effective WTRs to remove soluble P from PL, and they can be obtained at a minimal cost from drinking-water treatment plants. We set up batch and incubation experiments to determine: (1) the effect of WTR amendment rates on PL water-extractable P (WEP) concentrations and (2) the effects of incubation time, pH, and temperature on WEP concentrations of WTR-amended PL. Removal of PL-soluble P by the WTR was biphasic, showing an initial fast reaction (60% removal within 10 min) followed by a slower reaction that was completed within 12 days (90% removal). Phosphorus removal by the WTR was unaffected by pH changes in the range of 3-8. Incubation experiments showed that all WTR rates (2.5-15 wt.%) significantly (p < 0.001) lowered WEP concentrations in PL to approximately 40% of the unamended PL (no WTR) at 23 degrees C. Minimal reduction (20% of the unamended PL) in WEP concentrations for all WTR rates were observed up to 18 days, possibly due to P diffusion limitations. Increasing the temperature to 35 degrees C resulted in overcoming such diffusion limitations by increasing P removal rate of reaction. Assuming year-round availability of adequate quantities in nearby drinking-water treatment plants, WTR may be a cost-effective treatment to reduce P availability in poultry litter. Field experiments are greatly needed in order to demonstrate the excellent performance of WTR in this laboratory-based study to remove soluble P concentrations in animal waste.

AMENDMENTS FOR ENHANCING COPPER UPTAKE BY BRASSICA JUNCEA AND LOLIUM PERENNE FROM SOLUTION

Phytoextraction of metals is frequently limited by contaminant bioavailability and plant uptake rates. Chemical amendments can be added to increase the uptake and translocation of metals to aerial biomass. A range of amendments of various types was tested for increasing the copper uptake with the test species Indian mustard and ryegrass. These included citric acid (an organic acid); histidine (an amino acid); ethylenediaminetriacetic acid (EDTA), nitrilotriacetic acid (NTA), and ethelynediaminedisuccinic acid (EDDS) (aminopolycarboxylic acids); rhamnolipid (a biosurfactant); and Triton X-100 (a synthetic surfactant). EDTA was the most effective amendment for enhancing copper uptake and translocation into the shoots of Indian mustard and ryegrass, with respective shoot tissue copper levels of 1230 and 1360 μg-Cu/g-dry weight after 10 d compared to 90 and 220 μg-Cu/g-dry weight, respectively, in the unamended treatments. However, the EDTA application resulted in symptoms of toxicity in both Indian mustard and ryegrass, leading to drastic decreases in biomass yield. The application of high levels (300 mg/L) of the biodegradable chelator EDDS was found to be effective for improving translocation of copper in both species. The NTA addition provided benefits to root and shoot growth, with increased copper translocation to shoot tissue. Tests with biosurfactants and synthetic surfactants indicated detrimental effects on copper uptake, biomass yield, and the translocation of copper from roots to shoots in both plant species.

Efficacy of urease inhibitor to reduce ammonia emission from poultry houses

As the poultry industry has grown, so have concerns about the environmental management aspects of these industries, including air and water quality. Poultry operations continue to expand and are large contributors to farm income. There is increased concern related to ammonia emission from poultry operations. Various abatement methods, including dietary manipulation, chemical amendment of litter, and improvement in ventilation system management have been used to control ammonia concentrations from livestock facilities, but these methods are perceived to be too expensive, to impair bird growth, or to add to pollution in some other form. Alternative strategies include reduction of ammonia emissions by arresting N in the litter. An alternative approach to decrease ammonia emissions in poultry facilities is to block the enzyme activity in the litter because ammonia is the by-product of a 5-step enzymatic degradation of uric acid. Our preliminary study with layer feces, which were allowed to accumulate on a layer of broiler litter, indicated that a commercially available urease inhibitor resulted in a significant reduction in equilibrium ammonia concentration over time. Based on the results of the preliminary experiment, further studies were conducted to study the effect of the urease inhibitor on broiler litter and layer feces directly. The results showed that the urease inhibitor did not have any effect on equilibrium ammonia concentration when applied to drier broiler litter. The reduced moisture content in the broiler litter may have inhibited urease inhibitor activity. With layer feces, urease inhibitor reduced equilibrium ammonia concentration. The effect of the first application lasted for 1 wk, after which the equilibrium ammonia concentration in the treated trays rebounded to exceed that of the control trays. Upon a second application of urease inhibitor, the effect lasted for 14 d. The difference in the effect of the urease inhibitor on equilibrium ammonia concentration upon first and second application could have been influenced by a change in manure characteristics over time. Layer manure is a dynamic environment with continued change; therefore, more research is warranted in the area of stored layer manure.

Biochar: Carbon Mitigation from the Ground Up

As multibillion-dollar projects intended to sequester carbon dioxide (CO2) in deep geologic storage continue to seek financial support, the fertile black soils in the Amazon basin suggest a cheaper, lower-tech route toward the same destination. Scattered patches of dark, charcoal-rich soil known as terra preta (Portuguese for “black earth”) are the inspiration for an international effort to explore how burying biomass-derived charcoal, or “biochar,” could boost soil fertility and transfer a sizeable amount from the atmosphere into safe storage in of CO2 topsoil. Although burial of biochar is just beginning to be tested in long-term, field-scale trials, studies of Amazonian terra preta show that charcoal can lock up carbon in the soil for centuries and improve soil fertility. Charcoal is made by heating wood or other organic material with a limited supply of oxygen (a process termed “pyrolysis”). The products of the pyrolysis process vary by the raw material used, burning time, and temperature, but in principle, volatile hydrocarbons and most of the oxygen and hydrogen in the biomass are burned or driven off, leaving carbon-enriched black solids with a structure that resists chemical and microbial degradation. Christoph Steiner, a research scientist at the University of Georgia, says the difference between charcoal and biochar lies primarily in the end use. “Charcoal is a fuel, and biochar has a nonfuel use that makes carbon sequestration feasible,” he explains. “Otherwise there is no difference between charcoal carbon and biochar carbon.” Charcoal is traditionally made by burning wood in pits or temporary structures, but modern pyrolysis equipment greatly reduces the air pollution associated with this practice. Gases emitted from pyrolysis can be captured to generate valuable products instead of being released as smoke. Some of the by-products can be condensed into “bio-oil,” a liquid that can be upgraded to fuels including biodiesel and synthesis gas. A portion of the noncondensable fraction is burned to heat the pyrolysis chamber, and the rest can provide heat or fuel an electric generator. Pyrolysis equipment now being developed at several public and private institutions typically operate at 350–700°C. In Golden, Colorado, Biochar Engineering Corporation is building portable $50,000 pyrolyzers that researchers will use to produce 1–2 tons of biochar per week. Company CEO Jim Fournier says the firm is planning larger units that could be trucked into position. Biomass is expensive to transport, he says, so pyrolysis units located near the source of the biomass are preferable to larger, centrally located facilities, even when the units reach commercial scale.

Testing the potential of enhanced phytoextraction to clean up NORM and heavy metal contaminated soils

A greenhouse experiment was set up to evaluate the potential of enhanced phytoextraction to clean up U and heavy metal contaminated soils. One soil had a naturally high U concentration; the other soil was impacted by the radium extraction industry. Enhancement of solubility and uptake by plants (ryegrass and Indian mustard) was monitored after addition of 5 chemical amendments: citric acid, ammonium citrate-citric acid mixture, oxalic acid, EDDS and NTA. Solubilisation and uptake were highly influenced by the amendment applied and soil-plant combinations. For U, citric acid, the ammonium citrate-citric acid mixture or EDDS were most effective in increasing U uptake. EDDS was most effective in increasing Cu in mustard and ryegrass and Pb in ryegrass shoots. For other metals, increase in uptake was limited to at most a factor 5. Percentages annually removed with biomass ranged from 0.0002% to 1.52%., and were lowest for U, Cr and Pb and highest for Cd. A targeted 10% reduction in soil contaminant would require 7 years for Cd, 35 and 52 years for Cu and Zn, 203 and 384 years for U and Pb and 9433 years for Cr. Phytoextraction is hence not a feasible technique to decontaminate historically contaminated soils.