bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimates of Residual Dairy Manure Nitrogen Availability Using Various Techniques
Authors: Cusick Paul R. , Kelling Keith A. , Powell J. Mark , Muñoz Gabriela R. 
Published: October 2006

ABSTRACTIt is common practice to repeatedly apply dairy manure to the same fields. To accurately assess the total plant availability of manure nutrients, it is necessary to account for the nutrients remaining in soil from previous manure applications. A field experiment studying manure nitrogen (N) uptake by corn (Zea mays L.) was conducted from 1998 to 2003 on a Plano silt loam (fine‐silty, mixed, mesic, Typic Argiudolls). Plots received two rates of semisolid manure either every year, every 2 yr, or every 3 yr to estimate first‐, second‐, and third‐year dairy manure N residuals. Residual manure N availability was estimated from single and multiple manure applications using (i) the fertilizer N equivalence method, (ii) the apparent recovery (difference) method, (iii) relative effectiveness method, and (iv) recovery of 15N‐labeled manure. Second‐year availabilities after a single manure application using the fertilizer equivalence, difference, and relative effectiveness methods were estimated to be 12, 8, and 4% of total manure N applications, respectively. Estimates of third‐year availability by these methods were 3, 1, and 5%, respectively. Measurement of 15N recovered from labeled manure was 6 and 2% in the second and third year, respectively. Fertilizer equivalence, difference, and relative effectiveness methods showed great year to year variability, reducing the confidence in the residual manure N availability estimates by these methods, but using 15N‐labeled manures reduced variability substantially. Based on this and other studies, we suggest that second‐ and third‐year residual N availability from a single application of semisolid dairy manure would be 9 to 12%, and 3 to 5% of the original manure N application, respectively.
Compost, Manure, and Gypsum Application to Timothy/Red Clover Forage
Authors: Zheljazkov Valtcho D. , Astatkie Tess , Caldwell Claude D. , MacLeod John , Grimmett Mark 
Published: October 2006

ABSTRACTSome of the most fertile agricultural land in Atlantic Canada includes dykelands, which were developed from rich salt marshes along the Bay of Fundy through the construction of dykes. A 2‐yr field experiment was conducted on dykeland soil to evaluate the effect of fertility treatments: source‐separated municipal solid waste (SS‐MSW) compost, solid manure, commercial fertilizer, and gypsum on (1) timothy/red clover forage productivity, (2) N, S, and other nutrients uptake, and (3) residual NO3–N and NH4–N in the soil profile. All fertility treatments increased dry matter yields from the two cuts each year relative to the control. Residual soil NO3–N and NH4–N concentrations in the fall of the second year decreased with depth, and beyond 20‐cm depth were lower than 1 mg kg−1 Gypsum application equivalent to 40 kg S ha−1 increased dry matter yields and N uptake by forage, and increased soil Mehlich 3‐extractable S, tissue S, and uptake of S, Ca, P, Cu, Fe, and Mn relative to the control. High rates of compost can provide sufficient N, S, and perhaps other nutrients to a perennial forage system under the cool wet climate of Atlantic Canada with no heavy metal enrichment of forage. However, the chemical N provided greater total N uptake than organic sources, except the high rate of compost, suggesting that the N availability from organic sources was not well synchronized with forage N demand. Municipal solid waste compost may also increase soil and forage tissue Na, which might be of concern.
Antibiotic Transport via Runoff and Soil Loss
Authors: Davis J. G. , Truman C. C. , Kim S. C. , Ascough J. C. , Carlson K. 
Published: October 2006

ABSTRACTResearch has verified the occurrence of veterinary antibiotics in manure, agricultural fields, and surface water bodies, yet little research has evaluated antibiotic runoff from agricultural fields. The objective of this study was to evaluate the potential for agricultural runoff to contribute antibiotics to surface water bodies in a worst‐case scenario. Our hypothesis was that there would be significant differences in antibiotic concentrations, partitioning of losses between runoff and sediment, and pseudo‐partitioning coefficients (ratio of sediment concentration to runoff concentration) among antibiotics. An antibiotic solution including tetracycline (TC), chlortetracycline (CTC), sulfathiazole (STZ), sulfamethazine (SMZ), erythromycin (ERY), tylosin (TYL), and monensin (MNS) was sprayed on the soil surface 1 h before rainfall simulation (average intensity = 60 mm h−1 for 1 h). Runoff samples were collected continuously and analyzed for aqueous and sediment antibiotic concentrations. MNS had the highest concentration in runoff, resulting in the highest absolute loss, although the amount of loss associated with sediment transport was <10%. ERY had the highest concentrations in sediment and had a relative loss associated with sediment >50%. TYL also had >50% relative loss associated with sediment, and its pseudo‐partitioning coefficient (P‐PC) was very high. The tetracyclines (TC and CTC) had very low aqueous concentrations and had the lowest absolute losses. If agricultural runoff is proven to result in development of resistance genes or toxicity to aquatic organisms, then erosion control practices could be used to reduce TC, ERY, and TYL losses leaving agricultural fields. Other methods will be needed to reduce transport of other antibiotics.
Ground Cover Impacts on Sediment and Phosphorus Export from Manured Riparian Pasture
Authors: Butler David M. , Franklin Dorcas H. , Ranells Noah N. , Poore Matthew H. , Green James T. 
Published: October 2006

ABSTRACTMaintaining pasture ground cover is important in preventing environmental degradation of grasslands and associated riparian areas. The objective of this work was to determine the effect of ground cover on sediment and P export from pastured riparian areas under simulated rainfall events. Plots were established on two sites in the North Carolina Piedmont: a 10% slope with Appling sandy loam soils (fine, kaolinitic, thermic Typic Kanhapludults) and a 20% slope with Wedowee sandy loam soils (fine, kaolinitic, thermic Typic Kanhapludults), both with mixed tall fescue (Festuca arundinacea Schreb.)–dallisgrass (Paspalum dilatatum Poir.) vegetation. Existing forage stands were modified to represent a range of ground cover levels: 0, 45, 70, and 95% (bare ground, low, medium, and high cover, respectively), and amended with beef steer (Bos taurus) feces and urine (about 10 kg P ha−1). Mean runoff volume from bare ground was generally twice that observed from low, medium, and high levels of cover, which were similar. For all rainfall events combined, export of dissolved reactive P was greatest (P < 0.1) at bare ground and was reduced 31% at low cover, which did not differ from medium or high cover. Mean total Kjeldahl P export was greater (P < 0.001) from bare ground than from other cover levels. Results indicate that riparian bare areas can contribute substantial sediment (>215 kg ha−1) and P (0.7 kg P ha−1) to surface waters during heavy rainfall, whereas export may be reduced equally well by low cover (45%) as by high cover.
The Effect of Land Use on Soil Health Indicators in Peri‐Urban Agriculture in the Humid Forest Zone of Southern Cameroon
Authors: Monkiedje Adolphe , Spiteller Michael , Fotio Daniel , Sukul Premasis 
Published: October 2006

ABSTRACTThe objective of this study was to identify the effect of different land uses in peri‐urban agriculture on the soil properties. Soil health indicators were evaluated in the top 10 cm at five tilled agricultural sites involving different cropping systems and use of agrochemicals within the peri‐urban agricultural areas of Yaounde, Cameroon, and compared with a native forest land. The experimental data showed that the selected indicators were sensitive to cropping practice. Most cropped land had significantly higher total C, available N and P concentrations, soil pH, electrical conductivity, salinity, biomass C and P, dehydrogenase, β‐glucosidase, and acid phosphatase activities. Land producing corn (Zea maysL.) and sugarcane (Saccharum officinarumL.) differed from that producing tomatoes (Lycopersicon esculentumMill.), but cultivation of these crops has significantly impacted native soil quality. However, phenol oxidase, microbal biomass C/organic C (Cmic/Corg), and microbial biomass C/microbial biomass P (Cmic/Pmic) were negatively affected. These appeared to be more consistent indicators of negative management causing changes to soil health and may be suitable for an early appraisal of soil health.
Co‐composting of Acid Waste Bentonites and their Effects on Soil Properties and Crop Biomass
Authors: Soda Wannipa , Noble Andrew D. , Suzuki Shinji , Simmons Robert , Sindhusen La‐ait , Bhuthorndharaj Suwannee 
Published: October 2006

ABSTRACTAcid waste bentonite is a byproduct from vegetable oil bleaching that is acidic (pH < 3.0) and hydrophobic. These materials are currently disposed of in landfills and could potentially have a negative impact on the effective function of microbes that are intolerant of acidic conditions. A study was undertaken using three different sources of acid waste bentonites, namely soybean oil bentonite (SB), palm oil bentonite (PB), and rice bran oil bentonite (RB). These materials were co‐composted with rice husk, rice husk ash, and chicken litter to eliminate their acid reactivity and hydrophobic nature. The organic carbon (OC) content, pH, exchangeable cations, and cation exchange capacity (CEC) of the acid‐activated bentonites increased significantly after the co‐composting phase. In addition, the hydrophobic nature of these materials as measured using the water drop penetration time (WDPT) decreased from >10 800 s to 16 to 80 s after composting. Furthermore, these composted materials showed positive impacts on soil physical attributes including specific surface area, bulk density, and available water content for crop growth. Highly significant increases in maize biomass (Zea mays L.) production over two consecutive cropping cycles was observed in treatments receiving co‐composted bentonite. The study clearly demonstrates the potential for converting an environmentally hazardous material into a high‐quality soil conditioner using readily available agricultural byproducts. It is envisaged that the application of these composted acid waste bentonites to degraded soils will increase productivity and on‐farm income, thus contributing toward food security and poverty alleviation.
Cadmium Leaching from Micro‐Lysimeters Planted with the Hyperaccumulator Thlaspi caerulescens
Authors: Ingwersen Joachim , Bücherl Barbara , Neumann Günter , Streck Thilo 
Published: October 2006

ABSTRACTThe use of heavy metal hyperaccumulating plants has the potential to become a promising new technique to remediate contaminated sites. We investigated the role of metal mobilization in the Cd hyperaccumulation of Thlaspi caerulescens (J. & C. Presl, ‘Ganges’). In a micro‐lysimeter experiment we investigated the dynamics of Cd concentration of leachate as well as Cd removal by plant uptake in four treatments: (i) Control (bare soil), (ii) T. caerulescens, (iii) nonhyperaccumulator Brassica juncea (L.) Czern. (‘PI 426308’), and (iv) co‐cropping of the hyperaccumulator and nonhyperaccumulator. The experimental findings were analyzed using one‐ and two‐site rate‐limited desorption models. Co‐cropping of T. caerulescens and B. juncea did not enhance metal uptake by B. juncea Although Cd uptake of T. caerulescens was 10 times higher than that of B. juncea, the Cd concentration of leachate of the T. caerulescens treatment did not decrease below that of the B. juncea treatment. The Cd depletion in leachate was well reproduced by the two‐site rate‐limited desorption model. The optimized desorption coefficient was three orders of magnitude higher in the rhizosphere than in the bulk soil. Our results indicate that T. caerulescens accelerates the resupply of Cd from soil pointing to an important role of kinetic desorption in the hyperaccumulation by T. caerulescens
Bioaccessibility of Lead Sequestered to Corundum and Ferrihydrite in a Simulated Gastrointestinal System
Authors: Beak Douglas G. , Basta Nicholas T. , Scheckel Kirk G. , Traina Samuel J. 
Published: October 2006

ABSTRACTLead (Pb) sorption onto oxide surfaces in soils may strongly influence the risk posed from incidental ingestion of Pb‐contaminated soil. Lead was sorbed to model oxide minerals of corundum (α‐Al2O3) and ferrihydrite (Fe5HO8·4H2O). The Pb‐sorbed minerals were placed in a simulated gastrointestinal tract (in vitro) to simulate ingestion of Pb‐contaminated soil. The changes in Pb speciation were determined using extended X‐ray absorption fine structure (EXAFS) and X‐ray absorption near edge spectroscopy (XANES). Both corundum (sorption maximum of 2.13 g kg−1) and ferrihydrite (sorption maximum of 38.6 g kg−1) have been shown to sorb Pb, with ferrihydrite having a very high affinity for Pb. The gastric bioaccessible Pb for corundum was >85% for corundum when the concentration of Pb was >200 mg kg−1 Bioaccessible Pb was not detectable at ≤200 mg kg−1 Bioaccessible Pb ranged from 53 to 88% for ferrihydrite. The bioaccessible Pb was below detection limits for the intestinal phase in the ferrihydrite system. Solid phase speciation identified both inner‐ (mononuclear bidentate) and outer‐sphere species for Pb sorbed to corundum, while only an inner‐sphere (mononuclear bidentate) complex was found for ferrihydrite. Although corundum and ferrihydrite can bind Pb, they fail to significantly reduce gastric bioaccessible Pb but do reduce intestinal bioaccessible Pb. Treatment of Pb‐contaminated soil with corundum or ferrihydrite may reduce Pb solubility under field soil conditions of pH > 4. However, much of the sorbed Pb will become bioaccessible under gastric conditions (pH 1.5–2.5) if this soil is ingested. Caution should be used before using these materials to remediate a soil where soil ingestion is an important exposure pathway.
A Washing Procedure to Mobilize Mixed Contaminants from Soil
Authors: Ehsan Sadia , Prasher Shiv O. , Marshall William D. 
Published: October 2006

ABSTRACTWe conducted a laboratory study to assess the feasibility of a washing process with nonionic and anionic surfactants in combination with ethylenediaminetetraacetate (EDTA) for the simultaneous mobilization of heavy metals and polychlorinated biphenyls (PCBs) from a field‐contaminated soil. Unit processes consisting of complexometric extraction and surfactant‐assisted mobilization were combined with reagent regeneration and detoxification steps to generate innocuous products. Ten minutes of ultrasonic mixing of the soil with a combination of 30 mL L−1surfactant suspension and a sparing quantity (2 mmol) of EDTA mobilized appreciable quantities of PCBs, virtually all of the available Cd, Cu, Mn, and Pb, and lesser amounts of the Zn, Ni, and Cr but only small quantities of Al and Fe. Relative to individual reagents, combinations of surfactant (Brij 98, Triton X‐301, or Triton XQS‐20) with EDTA did not influence PCB extraction efficiencies perceptibly. Of the three surfactants, the Brij 98 proved to be the most efficient for three successive extractions with a single charge, mobilizing 83% of the PCBs, whereas companion extractions that used fresh reagent each time mobilized 87% of the soil PCB content. The decreased PCB mobilization with the same quantity of anionic surfactant (71 or 68%) resulted from losses during the EDTA regeneration process with zero‐valent Mg. In toto, these studies demonstrate that PCB compounds and selected heavy metals can be coextracted efficiently from soil with three successive washes with the same washing suspension containing EDTA and a nonionic surfactant.
A Washing Procedure to Mobilize Mixed Contaminants from Soil
Authors: Ehsan Sadia , Prasher Shiv O. , Marshall William D. 
Published: October 2006

ABSTRACTWe conducted a laboratory study to assess the efficiency of nonionic and anionic surfactants in combination with a sparing quantity of ethylenediaminetetraacetate (EDTA) to simultaneously extract heavy metals (HMs) and polychlorinated biphenyl (PCB) compounds from a field‐contaminated soil. A soil wash that mobilized both HMs and PCBs was combined with back‐extraction with hexane to remove PCBs from the aqueous wash. The aqueous washing suspension was then regenerated by precipitation of the HMs induced by corrosion and hydrolysis of zero‐valent Mg to provide a cleaned soil and innocuous extract. Finally, the washing suspension was recycled twice to mobilize more contaminants from the soil particulate fraction. After ultrasonic equilibration, EDTA in admixture with a nonionic surfactant did not appreciably change the efficiency of mobilization of most heavy metals (Al, Cd, Cr, Fe Mn, Ni, and Zn), but did increase the recovery of Cu and Pb. The release of EDTA from HM complexes was efficient for most metals (99%) but was influenced by the chemical characteristics of the surfactant. The EDTA recovery (62–65%) after three cycles of soil washing, hexane back‐extraction, and Mg0treatment was similar for all reagent combinations. In toto, these studies demonstrate that after treatment with ultrasound, selected heavy metals can be coextracted efficiently from soil with a single washing suspension containing EDTA and a nonionic surfactant.
Evaluation of Wetland Methyl Mercury Export as a Function of Experimental Manipulations
Authors: Gustin Mae Sexauer , Chavan Prithviraj V. , Dennett Keith E. , Marchand Eric A. , Donaldson Susan 
Published: October 2006

ABSTRACTMercury associated with natural enrichment, historic mining, and ore processing is a contaminant of concern in watersheds of the western USA. In this region, water is a highly managed resource and wetlands, known to be important sites of methyl mercury production, are often an integral component of watersheds. This study applied controlled manipulations of four replicated experimental wetland designs with different water and soil mercury concentrations to determine the potential impacts on methyl mercury export. Wetlands were manipulated by drying and wetting, changing hydraulic retention time, and adding sulfate and nitrate to influent waters. In a summer drying and wetting manipulation, an immediate increase in total methyl mercury release was observed with rewetting, however, concentrations decreased quickly. Drying all wetlands over the winter and rewetting in the spring resulted in high net methyl mercury output relative to that observed before drying. Net methyl mercury output was not influenced by changes in hydraulic retention time from 4 to 8 h or to 30 min, or by increasing the nitrate concentration from 0.1 to 10 mg L−1 The addition of sulfate to the inlet waters of two mesocosms to increase concentrations from ∼100 to 250 mg L−1 did not result in a clear effect on methyl mercury output, most likely due to sulfate concentrations being higher than optimal for methyl mercury production. Despite the lack of response to sulfate amendments, the change in sulfate concentration between the inlet and outlet of the mesocosms and temperature were the parameters best correlated with methyl mercury outputs.
Nitrogen‐ vs. Phosphorus‐based Dairy Manure Applications to Field Crops
Authors: Toth John D. , Dou Zhengxia , Ferguson James D. , Galligan David T. , Ramberg Charles F. 
Published: October 2006

ABSTRACTManagement of animal manures to provide nutrients for crop growth has generally been based on crop N needs. However, because manures have a lower N/P ratio than most harvested crops, N‐based manure management often oversupplies the crop‐soil system with P, which can be lost into the environment and contribute to eutrophication of water bodies. We examined the effects of N‐ vs. P‐based manure applications on N and P uptake by alfalfa (Medicago sativa L.), corn (Zea mays L.) for silage, and orchardgrass (Dactylis glomerata L.), leaching below the root zone, and accumulation of P in soil. Treatments included N‐ and P‐based manure rates, with no nutrient input controls and inorganically fertilized plots for comparison. Nitrate concentrations in leachate from inorganic fertilizer or manure treatments averaged 14 mg NO3–N L−1, and did not differ by nutrient treatment. Average annual total P losses in leachate did not exceed 1 kg ha−1 In the top 5 cm of soil in plots receiving the N‐based manure treatment, soil test P increased by 47%, from 85 to 125 mg kg−1 Nitrogen‐ and P‐based manure applications did not differ in ability to supply nutrients for crop growth, or in losses of nitrate and total P in leachate. However, the N‐based manure led to significantly greater accumulation of soil test P in the surface 5 cm of soil. Surface soil P accumulation has implications for increased risk of off‐field P movement.
Membrane Filtration Coupled with Chemical Precipitation to Treat Recirculating Aquaculture System Effluents
Authors: Yang Ling , Zhou Hongde , Moccia Richard 
Published: October 2006

ABSTRACTEffluents from recirculating aquaculture systems (RAS) contain high concentrations of nitrogen and phosphorous wastes and thus often require proper treatment to prevent potential detrimental impacts on receiving water bodies. The purpose of this study was to evaluate the feasibility of membrane filtration coupled with chemical precipitation as a pretreatment step with emphasis on phosphorus removal from RAS effluents. Chemical precipitation tests were conducted by adding magnesium chloride and alum at different chemical concentrations and pH values, respectively. Crossflow, flat‐sheet membrane filtration modules were used to examine the effects of transmembrane pressure and crossflow velocity in terms of solid/liquid separation efficiency and permeate flux decline. The results showed that membrane filtration can effectively separate the phosphorus precipitates after chemical precipitation. The total phosphorus in the treated effluent was reduced to less than 0.05 mg L−1 with a removal efficiency of more than 90%. However, much lower removal efficiencies were obtained for total organic carbon (TOC), total nitrogen, and turbidity. It was concluded that membrane filtration coupled with chemical precipitation can become an effective, compact treatment technology to meet the stringent regulatory requirements for RAS effluent discharge.