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Land application is the preferred method for utilization of poultry litter. Ammonia volatilization was rapid immediately after litter application by Sharpe et al. (33:1183–1188) and stopped within 7 to 8 d. Ammonia losses to the atmosphere ranged from 3 to 24% of applied N during the winter and summer, respectively. Largest losses occurred during hot, dry, windy conditions. Losses of 24% of the applied ammonia could result in N deficiency in crops and could potentially be harmful to the environment. Precipitation of 17 mm essentially halted ammonia losses to the atmosphere. Results are applicable to the 51 million acres of conservation tillage in the U.S. Southeast.
Nitrogen Cycling in Swine Production
Confined animal farm operations provide increased production efficiency, improved production economics, and a better industry support system for individual producers; however, concentrating large numbers of animals in relatively small geographical areas may also present a challenge to manage wastes to minimize ammonia losses, a trace gas which may affect the nutrient status of the surrounding environment. Harper et al. (33:1189–1201) placed gas and microclimate sensors over two lagoons to determine emission rates using noninterference techniques. Ammonia emissions varied daily and seasonally and were related to nutrient concentration, acidity, temperature, and wind conditions. Emissions on two lagoons in North Carolina were compared and when emissions were based on animal numbers, total farm emissions were not representative of actual emissions, exemplifying the danger of basing emissions on animal numbers. Significant (almost half) quantities of N in the lagoons were denitrified to benign N gas. Ammonia emissions were significantly less than in previous studies; however, a total N balance of the farm (accounting for 95% of all incoming N) showed the ammonia emissions were appropriate for this production system.
Combining Chemistry and Biology for Soil Remediation
Wastes generated from the manufacture or decommissioning of munitions currently contaminate soils at many sites around the world. Previous methods for the remediation of these wastes have been based solely on either chemical or biological means. A newly developed process that couples both chemical and biological degradation has been shown by Schrader and Hess (33:1202–1209) to be more effective than either technology alone and may produce up to 73% destruction of TNT in soil slurries.
Enhanced Oil Bioremediation in Sediments
Amendment of water-soluble nutrients to open beach environments for oil bioremediation is often impractical as nutrients can be rapidly diluted and leached out of the sediment profile. Xu et al. (33:1210–1216) found that the application of 1.2% (w/w) Osmocote, a commercialized slow-release fertilizer, resulted in a sustained high level of nutrients (NH+4–N, NO–3–N, and PO3–4–P) in an oil-contaminated beach sediment on an intertidal foreshore environment over the duration of a 105-d experiment in Singapore. The metabolic activity of the indigenous microbial biomass was significantly elevated relative to an unamended control sediment, and the biodegradation rates of aliphatic and polycyclic aromatic hydrocarbons were enhanced by the addition of Osmocote. Osmocote is an effective slow-release nutrient source for enhanced oil bioremediation on the intertidal foreshore.
Nitrogen Transformations are Critical for Soil Nitrogen Simulation
Policymakers need instruments to evaluate surface and ground water vulnerability to soil agricultural pollutants, such as fertilizer-deriving nitrates. Simulation models, able to efficiently simulate soil water flow and nitrate dynamics, may help fulfill this task. Marchetti et al. (33:1217–1229) tested the efficiency of the model MACRO-SOILN in simulating soil water and nitrate content, which had been measured in two field experiments comparing different soils, cropped to corn and fertilized with urea and/or pig slurry. The model showed good efficiency in simulating soil water content but failed to correctly simulate soil nitrate content. Model performance could partly be improved by modifying the setting of ammonia emissions and selected N transformation parameter values.
Forage Systems to Reduce Ground Water Nitrate
Some agricultural systems, including high-fertility pastures, can cause nitrate levels in ground water to exceed maximum contaminant levels (MCL). Owens and Bonta (33:1230–1237) measured NO3 levels above MCLs in ground water under high-fertility pastures that were rotationally grazed by a cow/calf beef herd on sloping land in eastern Ohio. Two forage management systems were studied to evaluate the possibility of reducing NO3 levels in ground water. Removing forage as hay and rotational grazing with no N fertilizer being added to either management system were evaluated. Both practices showed a reduction in NO3 levels and amounts of N leached during a five-year study. Although low N inputs would probably produce the same results, it would take longer. But this research showed that if areas with high N loading have resulted in high NO3 levels in the ground water, a livestock producer can achieve lower NO3 losses and acceptable ground water NO3 quality under haying or continued grazing with low N inputs.
Fall and Winter Manure Application Effects on Mineral Nitrogen Leaching
Land application of manure is common in the upper midwestern United States. Recently, there have been concerns regarding the impact of this practice on water quality, especially when manure is applied during winter over frozen soils. Gupta et al. (33:1238–1246) report the effects of tillage and timing of manure (dairy) application on subsurface water quality from a silt loam soil. Liquid dairy manure was applied in fall (before snow) or in winter (over snow with frozen soil underneath), to be compared with no manure under two tillage systems (no-till and chisel-plowing). Percolation and mineral N leaching during the nongrowing season were, respectively, 72 and 78% of the annual losses, mainly because of the absence of plant water and N uptake. Percolation was generally higher from no-till compared with chisel plow, but there was no significant effect of tillage on mineral N concentration of the leachate or mineral N losses via leaching. Mineral N leaching was statistically higher from manure applied vs. no manure treatment, but there was no difference between winter-applied manure and no manure treatments. Fall manure application followed by chisel-plowing resulted in highest N leaching losses due to enhanced mineralization of both soil and manure organic N.
Nonmetallic Vegetables Thanks to Nutrients
Toxic heavy metals may be accumulated in aquatic plants that are used as food for humans and fodder for domestic animals, and may thus be a threat to human health. Metal-induced toxic effects may also affect yield of the plants. Göthberg et al. (33:1247–1255) found that the lower the nutrient strength in the medium, the higher were the metal concentrations that accumulated in different plant parts of water spinach and the bigger were the metal-induced toxic effects in plants. In regard to metal pollution, fertilizers may thus protect yield and health of both plants and consumers.
Metal Speciation in Methanogenic Granular Sludges
The speciation of trace metals within anaerobic granular sludges from upflow anaerobic sludge bed (UASB) reactors was determined by Osuna et al. (33:1256–1270) using a chemical sequential extraction procedure. This showed that anaerobic granular sludges display significantly different metal distributions. The types of available precipitates within the granular sludge were found to influence the trace metal distribution as well as the sorption capacity of an anaerobic granular sludge. Cobalt sorption onto granular sludge was shown to depend on both chemical (Co, Ni, and Fe concentration, pH) and physical (matrix structure) parameters.
Phytoextraction by the Halophyte Species Mediterranean Saltbush
To identify Cd- and Zn-accumulating plants exhibiting a high growth rate, Lutts et al. (33:1271–1279) submitted seedlings from a metallicolous ecotype of Mediterranean saltbush (Atriplex halimus L.) for three weeks to 0.1 mM Cd or 0.1 mM Zn in a nutrient solution. All plants remained alive and no significant growth inhibition was recorded until the end of the experiment. Plants accumulated high amounts of Cd in their aerial parts. It is concluded that Mediterranean saltbush is a promising species for phytoextraction purposes.
Copper–Humic Substances in Contaminated Soil during Electroremediation
Speciation and the possible reaction pathways of Cu–humic substances (Cu–HS) in contaminated soil during electrokinetic remediation (EKR) were investigated by Liu and Wang (33:1280–1287). The main Cu species in the contaminated soil were Cu–HS (50%), CuCO3 (28%), Cu2O (11%), and CuO (11%). The Cu–HS in the contaminated soil had equatorial and axial Cu–O bond distances of 1.94 and 2.17 Å with coordination numbers (CNs) of 3.6 and 1.4, respectively. After 180 min of EKR, the axial Cu–O bond distance in the Cu–HS complexes was increased by 0.15 Å, suggesting a ligand exchange of the Cu–HS with H2O molecules in the electrolyte. About 50% of the Cu–HS complexes (24% of total Cu) in the soil were dissolved and formed [Cu(H2O)6]2+ in the electrolyte and 71% (17% of total Cu in the soil) of which migrated to the cathode under the electric field (5 V/cm).
Lead Speciation in Phosphorus-Amended Soils
Immobilization of Pb in soils via phosphate amendments as pyromorphite has been studied extensively. However, determining the extent of pyromorphite formation during the immobilization process has not been accomplished. Scheckel and Ryan (33:1288–1295) investigated the Pb chemistry in phosphate-amended, Pb-contaminated soils by X-ray absorption fine structure spectroscopy coupled with linear combination fitting to determine the speciation and quantification of major Pb components. The addition of P promoted pyromorphite formation and the rate of formation increased with increasing P concentration. As a low-cost alternative to site removal, pyromorphite formation in Pb-contaminated soils possesses great potential.
Nitrate Not Removed in Agricultural Streams
Excess nitrate in streams and rivers is a major concern in agricultural regions of the Mississippi River basin. For streams in agricultural watersheds, the amount of nitrate removed through denitrification is unknown, as is the effect denitrification has on the distance traveled by nitrate in such streams. Royer et al. (33:1296–1304) examined headwater streams in Illinois and report that denitrification had little influence on the transport of nitrate, despite often high rates of in-stream denitrification. The degree to which denitrification acted as an effective N sink was controlled by hydrological factors, such as discharge from agricultural drain tiles. The fate of nitrate in the Illinois streams appeared to be transport to downstream water bodies, rather than removal through denitrification. Results suggest that previous N budgets for the region may have overestimated N loss through in-stream denitrification.
Surfactants Aid Zerovalent Iron in Destroying HMX
Soils contaminated at military sites often contain mixtures of explosives such as HMX, RDX, and TNT rather than a single compound. When zerovalent Fe was used to treat munitions-contaminated soil, high rates of destruction were observed for RDX and TNT, but not HMX. Park et al. (33:1305–1313) evaluated several surfactants and found that the cationic surfactants HDTMA and didecyl were effective in increasing HMX solubility and facilitating Fe-mediated destruction of HMX.
Metal Cross-Linking Effect on Sorption Behavior of Humic Acid
Cross-linking can reduce macromolecular mobility and increase the glassy character of macromolecular solids. Polyvalent metal ions are capable of cross-linking humic substances by coordinating with multiple functional groups on humic macromolecules. Lu and Pignatello (33:1314–1321) studied sorption of naphthalene and 1,2,4-trichlorobenzene on Al3+–cross-linked soil humic acid prepared by flocculating the H+ form. They found that Al3+–cross-linking leads to greater nonlinearity, hysteresis, and bisolute competitive effects relative to the H+ form, validating the hypothesis that metal ion cross-linking creates a more rigid-chain structure. The study supports a link between nonideal sorption and the glassy character of SOM, and underscores the importance of metal ions on humic structure vis a vis sorption of hydrophobic organic compounds.
Cation–
Bonding of Polycyclic Aromatic Hydrocarbons at Mineral Surfaces
Recent molecular modeling and spectroscopic studies have suggested relatively strong interactions can occur between aromatic donors and metal cations in aqueous solutions. Zhu et al. (33:1322–1330) characterized potential cation– interactions between -donor polycyclic aromatic hydrocarbons (PAHs) and exchangeable cations accumulated at mineral surfaces via both spectroscopic and batch sorption methods. They found that saturating minerals with soft transition metals or soft base cations enhances sorption of PAHs to mineral surfaces via the underlying cation– bonding mechanism.
Soil Sorption of Sulfonamide Antibiotics
Residues of pharmaceutical antibiotics, whose fate and effects are governed by sorption, are found in the environment. Thiele-Bruhn et al. (33:1331–1342) investigated the extent and mechanisms of the sorption of sulfonamide antibiotics in topsoils and soil fractions by combining results from batch experiments, characterization of mineral and organic constituents of organic-mineral soil surfaces, and molecular modeling. Sulfonamide sorption was governed by: (i) the molecular structure and physicochemical properties of sulfonamides, (ii) accessible functional groups at organic–mineral surfaces, and (iii) the accessibility of voids and cavities in the three-dimensional structure of soil organic matter and its combinations with the mineral matrix forming organic–mineral complexes. It appears that in soils, binding moieties of high polarity interact preferably with the polar functional groups of sulfonamides.
Soil Polycyclic Aromatic Hydrocarbon Release in the Gut
Oral uptake of contaminated soils is considered an important route for human exposure to environmental contaminants. Gut processes that influence contaminant desorption and complexation are not well understood, yet they largely influence contaminant bioavailability. Van de Wiele et al. (33:1343–1353) used an in vitro model of the human gut and a mathematical model to describe gut processes for soil-bound polycyclic aromatic hydrocarbons (PAH). They discovered that higher PAH release in the gut is not necessarily related to higher bioavailability. Complexation processes of released PAHs with organic matter and bile salts partly resulted in aggregates too large for intestinal absorption. These are crucial processes when assessing the bioavailable fraction of ingested contaminants.
Sorption of Prosulfuron by Variable-Charge Soils and Model Sorbents
Prosulfuron, a relatively new sulfonylurea herbicide, is a weak acid (pKa 3.76), and therefore will undergo pH-dependent speciation and sorption. Hyun and Lee (33:1354–1361) investigated prosulfuron sorption form amorphous silica, 
-alumina, CaSwy1-montmorillonite, commercial humic acid, an anion exchange resin, and 10 variable-charge soils as a function of pH and ionic composition. Anion exchange of prosulfuron accounted for as much as 82% of the sorption measured in the pH range from 3 to 7. The relative contribution of anion exchange to sorption was positively correlated to the ratio of anion and cation exchange capacities. Both anion exchange and hydrophobic sorption decrease with increasing pH, thus addition of fertilizer and lime amendments may enhance the potential for off-site leaching of recently applied acidic pesticides.
Sorption and Degradation of CL-20 in Soil
CL-20 is a new polycyclic nitramine explosive being considered for use as a munition. To limit the adverse environmental consequences arising from its widespread use, Balakrishnan et al. (33:1362–1368) assessed the behavior of this energetic chemical in soil. They revealed that CL-20 can be strongly retained by soils, and retention is governed by the soil organic content. Furthermore, although immobilization onto soils retards abiotic degradation, in alkaline soils CL-20 still decomposes and thus will not be a persistent contaminant.
Disturbances in Rock-Rose Plants by Sea Aerosol
Differences among species in productivity as a response to sea aerosol application have been described. Sànchez-Blanco et al. (33:1369–1375) report that white-leaf rock-rose (Cistus albidus L.) was more sensitive to sea aerosol than Montpellier rock-rose (C. monspeliensis L.), showing greater leaf damage and markedly decreased growth. In white-leaf rock-rose, the presence of surfactant enhanced the phytotoxic effect, leading to greater mortality. Montpellier rock-rose was more efficient at decreasing the toxic salt content, probably because of its greater ability to compartmentalize toxic ions at the cellular level. In this species, the combined action of salt and surfactant did not enhance the phytotoxic effect. Native ornamental species of wild flora are interesting options for use in landscaping and gardening projects.
UVB Radiation Modifies Herbicide Selection
Ultraviolet-B (UVB) radiation is an environmental stress for plants and this situation could become aggravated in the next decades. Martínez-Ghersa et al. (33:1376–1386) show that UVB light is a weak stress factor for ryegrass plants. However, when herbicide selection pressure is high, UVB light can reduce the evolution toward herbicide tolerance. When selection pressure on the parent plants is lower, the two stress factors have a synergistic effect, causing changes in herbicide efficacy that in turn have demographic and evolutionary consequences. In the field, these interactions between stress factors might be of significance for annual weeds in which seed output is a major determinant in fitness.
Phosphorus Concentration Changes with Distance from Growing Roots
Root growth can modify the soil around the growing root and alter nutrient availability and uptake. However, until recently we had no way to observe these changes on a near-real-time basis. The development of micro-suction cups in conjunction with capillary electrophoresis analytical methods allows us to now collect and analyze extremely small samples of soil solution (100 µL) directly adjacent to growing roots. Analysis of these samples by Wang et al. (33:1387–1392) indicated that P concentration changes significantly within a few millimeters of a growing root and the magnitude of this change varies as a function of time, distance, and plant species.
Soil Phosphorus Desorption Dynamics
Kinetics of P desorption is important as it may control the availability of P for plant uptake and leaching. Koopmans et al. (33:1393–1402) determined P desorption kinetics in batch experiments using soils from a pot experiment where grass was cropped on a P-rich noncalcareous sandy soil without P addition. A diffusion model was used to simulate P desorption kinetics from a spherical aggregate. Furthermore, a simple tool is presented, referred to as the dynamic bioavailability index (DBI), to determine whether kinetics of P desorption limited plant uptake in the pot experiment. This tool is the dimensionless ratio of the modeled maximal diffusive flux from soil aggregates to solution and the measured plant uptake rate. The DBI could be seen as a promising onset to a new dynamic approach of bioavailability.
Phosphorus Loss from Rice Fields
Phosphorus poses a threat to waters in the Taihu Lake basin in China. Nonpoint-source pollution from watershed and release of P from lakebed sediment are two major sources of P contributing to water eutrophication. The potential transfer of P in rice fields through surface drainage and subsurface flow was investigated by Zhang et al. (33:1403–1412) under simulated conventional irrigation–drainage management. Phosphorus concentrations and loads in field floodwater on plots receiving P rapidly declined in a nonlinear manner, and the combined applicaton of fertilizer and manure P resulted in higher P transfer potential in field floodwater than with fertilizer P alone one week after P application. Phosphorus concentrations in interflow water sampled by suction cups inserted at a depth of 150 to 200 mm gradually increased within two weeks after P application, then declined. Results indicate that avoiding overflow drainage after P input and extending the time between P application and drainage may reduce P losses from rice paddies.
Phosphorus Transport in Surface Runoff
Research on P transport in surface runoff relies on a variety of runoff monitoring tools. Kleinman et al. (33:1413–1423) compared runoff properties from soil boxes and field plots under simulated rainfall. They found similarities in the relationship of soil P with dissolved P in runoff between poorly drained soil boxes prone to erosion and well-drained, grassed field plots. When they broadcast manures onto shallow and deep soil boxes, the hydrology of shallow soil boxes did not change conclusions regarding dissolved P in runoff. Results point to the limited but practical value of packed soil boxes in the study of P transport.
Phosphorus Incorporation and Source Influence Losses
Land application of animal manures can result in an increased potential for excessive P losses in runoff to nutrient-sensitive surface waters. Tarkalson and Mikkelsen (33:1424–1430) discovered that under some conditions P in broiler litter was susceptible to losses in rainfall runoff, especially when applied and left on the surface of agricultural land. When left on the surface of the soil, more P in broiler litter was lost in runoff than the P in inorganic fertilizer. The loss of P in runoff was reduced if the broiler litter and inorganic fertilizer were incorporated before a rainfall event. High-intensity rainfall events shortly after broiler litter application to the soil surface can result in high in-field losses of P in runoff.
Phosphorus in Runoff from Soil Receiving Phytase and High Available Phosphorus Corn Manure
Total P concentration in poultry manure can be significantly reduced by supplementing poultry diets with phytase enzyme and high available phosphorus (HAP) corn. However, less is known about the effect of the diet on manure P solubility and its potential for causing nonpoint P runoff losses. Analysis of turkey manures by Penn et al. (33:1431–1439) showed that phytase and HAP corn diets reduced both total P and dissolved P contents of the resulting manure. However, there were few differences between diets in dissolved P and total P in surface runoff when the manures were surface-applied at equal total P rates onto established tall fescue in soil boxes and placed under a rainfall simulator. Under these conditions, runoff dissolved P losses appeared to be a function of both manure dissolved P concentration and amount of manure particles directly lost in runoff. Manure produced from phytase enzyme and HAP corn diets possess no greater risk to water quality than conventional turkey diets.
Nitrogen Compounds along the Lower Jordan River
Implementation of the water sections of the peace agreement between Israel and Jordan, and the countries' commitment to improve the ecological sustainability of the Lower Jordan River system, require a better understanding of the riverine environment. Segal-Rozenhaimer et al. (33:1440–1451) investigated the sources and transformations of N compounds in the Lower Jordan River by applying a combination of physical, chemical, isotopic, and mathematical techniques. Source waters of the Lower Jordan River contain sewage, which contributes high ammonium loads to the river. They found that ammonium concentration decreased along the first 20 km of the Lower Jordan River and nitrate concentration increased. Geochemical and mathematical analysis indicated that intensive nitrification occurs between river kilometers 5 and 12, while increasing nitrate concentration further downstream is attributed to an external subsurface water source that enters the river.
Soil Properties Affect Phosphorus Loss
Phosphorus loss in runoff from agricultural fields has been identified as an important contributor to eutrophication. Schroeder et al. (33:1452–1463) conducted simulated rainfall studies on undisturbed pasture plots with a single soil series to determine the relationship between P in runoff and several measures of soil P availability. There were positive correlations between all soil measures of soil P availability and all forms of P in runoff. However, when variability within the soil series was accounted for, the relationship between soil test P and runoff P was much stronger. The ratio of oxalate-extractable Fe to Al had the greatest effect on the relationship between soil P and runoff P. Results indicate that within soil series variability may affect the relationship between soil P and potential for P loss in runoff.
Colloidal Phosphorus in Irrigation Runoff
Colloidal particles smaller than 1 µm in diameter can be efficient in transporting pollutant P in runoff from farmland, but such particles remain poorly understood. Turner et al. (33:1464–1472) report that colloidal P is much more important in runoff from irrigated agriculture than previously thought. In some cases, more than half the P in water samples passing through a 1-µm filter was associated with colloids. In runoff from calcareous soils common to much of the irrigated western United States, these particles are mainly calcium phosphates that only become soluble at relatively low pH values. These results demonstrate an important limitation on our understanding of pollutant P transport in runoff from irrigated agriculture.
Preferential Flow of Pesticides to Ground Water
Preferential flow may lead to unacceptable pesticide concentrations in ground water and surface water. Scorza Júnior et al. (33:1473–1486) studied leaching of bentazon and imidacloprid in a field experiment on a cracking clay soil under realistic worst-case conditions for Dutch agriculture. Drain discharge occurred only while ground water level was shallower than the level of tile drains (80–90 cm depth). Evidence for preferential flow was found mainly for wet periods in which no shrinkage cracks were observed at the soil surface. Highest drainwater concentrations were found at the first drainage event and these concentrations were about an order of magnitude higher than ground water concentrations at the 100- to 120-cm depth. Cause of this difference is probably that water flowing to tile drains is less diluted by clean water in the saturated zone than water in the saturated zone below tile drains.
New Model Captures Pesticide Pollution
Shallow ground water pollution from the large-scale application of pesticides is a serious environmental problem in many areas where modern mechanized farming methods are used. However, quantitatively assessing the extent and magnitude of ground water contamination with field measurements or physically based computer models on these large scales is extremely difficult due to cost and availability of data. Stewart and Loague (33:1487–1498) applied a new type transfer function (TTF) model that uses characteristic functions based on soil textures and their leaching properties. The model was used to assess leaching after one application of the common herbicide atrazine in the San Joaquin Valley (California). Modeling results showed that a pesticide leaching assessment with the TTF model is possible with comparatively little computational cost, and estimated atrazine concentrations can be related to soil survey information. Areas with high potential vulnerability to atrazine leaching were found for soils with low organic C content and sandy loam and loam textures. The TTF modeling approach is shown to be a useful tool for quantitative pesticide leaching assessments at regional scales significantly larger than those of previous studies.
Release of Cryptosporidium and Giardia from Dairy Cattle Manure
Various physical factors affecting the release rate of naturally occurring Cryptosporidium parvum oocysts and Giardia duodenalis cysts from dairy manure disks to sprinkled water were studied by Schijven et al. (33:1499–1508). An effect of temperature (5 or 23°C) on the release of manure and (oo)cysts was not apparent. Manure and (oo)cyst release rates from cow manure decreased faster than those from calf manure, and (oo)cyst release efficiencies from cow manure were higher than those from calf manure. In comparison with mist application, dripping water resulted in higher release rates of manure and (oo)cysts and in higher (oo)cyst release efficiencies due to the increased mechanical forces associated with droplet impact. Mist application at a higher flow rate resulted in faster release, but did not affect the (oo)cyst release efficiencies.
Composts Need Legume Adaptability
Difficulties in predicting N supply from composts have limited their routine use in crop production. Lynch et al. (33:1509–1520) report that in a pure grass perennial forage crop, cumulative yields obtained for one of three compost treatments alone matched that obtained for inorganic fertilizer. In a legume–grass crop, however, the legume component acted as an effective "N buffer," maintaining forage yield and protein content consistently higher, and within a narrower range, across all treatments. Integrating compost utilization into livestock systems that use legume–grass mixtures may reduce the risk of large excesses or deficits of N, moderate against potential losses in crop yield and quality, and by accommodating lower application rates of composts, reduce soil P and K accumulation.
Phosphorus Speciation in Manure-Amended Soils
Soil amendment with manure introduces P that exists in both organic and inorganic forms. Hansen et al. (33:1521–1527) used solution 31P nuclear magnetic resonance (NMR) spectroscopy and conventional P fractionation and speciation methods to investigate P forms in dairy manure and liquid lagoon manure, and to study how long-term amendment with these manures influenced surface and subsurface soil P speciation. Phosphorus forms in solid and lagoon manure were similar. About 30% of the total P was organic, mostly as orthophosphate monoesters. The majority of organic P in the soils is also phytic acid, and the surface soils were enriched with phytic acid compared with the subsurface soils.
Phosphorus Distribution in Dairy Manures
Phosphorus exists in animal manure in various forms. He et al. (33:1528–1534) investigated the distribution of P forms in 13 dairy manures obtained from different sources. Although the amounts of P forms were different in these manures, relationships of some P forms with total manure P were observed. Water-extractable inorganic P, the major inorganic P component, and phytate-like P, the major enzymatic hydrolysable organic P, were both positively correlated to total manure P. Findings could enhance our understanding of manure P chemistry, providing insight into improving management of manure P.
Effective Phosphorus Runoff Control
Excessive P fertilization to croplands can lead to P loss to waters. Daverede et al. (33:1535–1544) found that P runoff is related to the initial soil P level, P application method, and time elapsed between P application and successive rainfall simulations. Their study evaluated the effects of soil test P level, source (swine manure or triple superphosphate), and application method (surface-applied or incorporated) on P in runoff following soybean. Injection of liquid swine manure and chisel-plowing inorganic P fertilizers reduced P runoff significantly compared with surface application. Phosphorus runoff one month after surface application of P was significantly greater than P runoff during the second rainfall simulation, six months later. When P was incorporated, soil P level and sediment concentration and load were positively related to P runoff. Incorporating P, keeping soil P extraction values at agronomic levels, and reducing erosion were successful techniques for maintaining low P runoff.
Nutrients Released from Estuarine Sediments
Excess nutrients in Florida's lakes, rivers, and estuaries have caused environmental problems such as algal blooms, low dissolved oxygen levels, and fish kills. The 1972 Clean Water Act required states to identify pollutant water bodies and establish total maximum daily loads for nutrients. Malecki et al. (33:1545–1555) discovered that the amount of nutrients from the sediment to the water column represents a significant level. Ecosystem managers should take into account these nutrients when determining the total maximum daily loads for the Lower St. Johns River estuary. Dissolved reactive P and ammonium flux from sediments were measured under aerobic and anaerobic water column conditions using intact cores, to estimate the overall contribution of sediments to P and N loading to the estuary. Results suggest that the contribution of internal loading will likely decrease as external loading is decreased over time, thereby improving water quality of the Lower St. Johns River estuary.
Analysis of Hydrocarbons from Steam-Classified Municipal Solid Waste
Steam classification is a patented technology that involves treatment of municipal solid waste with steam under pressure to yield a cellulosic biomass product that can be used as a fuel or in building materials. Leahy et al. (33:1556–1561) demonstrate the utility of the steam classification process in removing hazardous semivolatile organic compounds (SVOCs) and volatile organic compounds (VOCs) from municipal solid waste. Results show that at least two SVOCs and at least 17 VOCs can be removed from the waste. The most commonly identified compounds were diethylphthalate, styrene, 1,4-dichlorobenzene, toluene, and 1,1,1-trichloroethane. Findings suggest that steam classification represents an effective technology for significant reduction or removal of hazardous organics from the waste stream, and, consequently, in reducing the extent of environmental contamination associated with landfill leachates and gases.
Easy, Continuous Measurements of Redox Potential in Soil
Manual measurements of redox potential in wetlands can be time consuming and are limited in showing variations in time and space. Continuous measurements using autonomous dataloggers can help in that perspective and, hence, in understanding ecosystem processes in wetland soils. Vorenhout et al. (33:1562–1567) developed a measuring set named Hypnos. Redox potential and temperature are measured at three depths in user-defined intervals. Results show variations in redox potential of 400 mV in salt marshes and sandy soils depending on flooding frequency and temperatures. The developed probes proved to be very stable, even after eight months of in situ operation. Easy, continuous measurements of redox and temperature are now in reach for everyone.
Sunlight Degrades Endocrine-Disruptor 4-Nonylphenol
4-Nonylphenol is an endocrine disruptor and has been frequently detected in biosolids at high concentrations. Land application of biosolids could potentially introduce large quantities of this chemical into the environment. Xia and Jeong (33:1568–1574) report that sensitized photolysis reaction plays an important role in degrading 4-nonylphenol in surface-applied biosolids. A laboratory experiment showed, within 30 days of exposure to artificial sunlight, a 55% reduction of 4-nonylphenol in the top 5-mm-layer of biosolids applied to soil. Thus, surface application rather than soil incorporation of biosolids could be effective in reducing biosolids-associated organic chemicals that can be degraded through photolysis reactions.
Related articles in JEQ:
Bonding: A New Perspective on the Sorption of Polycyclic Aromatic Hydrocarbons to Mineral Surfaces
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