bluuebunny/crossref_metadata_2025_split huggingface dataset:
EPIC Modeling of Soil Organic Carbon Sequestration in Croplands of Iowa
Authors: Causarano Hector J. , Doraiswamy Paul C. , McCarty Gregory W. , Hatfield Jerry L. , Milak Sushil , Stern Alan. J. 
Published: June 2008

AbstractDepending on management, soil organic carbon (SOC) is a potential source or sink for atmospheric CO2 We used the EPIC model to study impacts of soil and crop management on SOC in corn (Zea mays L.) and soybean (Glycine max L. Merr.) croplands of Iowa. The National Agricultural Statistics Service crops classification maps were used to identify corn–soybean areas. Soil properties were obtained from a combination of SSURGO and STATSGO databases. Daily weather variables were obtained from first order meteorological stations in Iowa and neighboring states. Data on crop management, fertilizer application and tillage were obtained from publicly available databases maintained by the NRCS, USDA‐Economic Research Service (ERS), and Conservation Technology Information Center. The EPIC model accurately simulated state averages of crop yields during 1970–2005 (R2 = 0.87). Simulated SOC explained 75% of the variation in measured SOC. With current trends in conservation tillage adoption, total stock of SOC (0–20 cm) is predicted to reach 506 Tg by 2019, representing an increase of 28 Tg with respect to 1980. In contrast, when the whole soil profile was considered, EPIC estimated a decrease of SOC stocks with time, from 1835 Tg in 1980 to 1771 Tg in 2019. Hence, soil depth considered for calculations is an important factor that needs further investigation. Soil organic C sequestration rates (0–20 cm) were estimated at 0.50 to 0.63 Mg ha−1 yr−1 depending on climate and soil conditions. Overall, combining land use maps with EPIC proved valid for predicting impacts of management practices on SOC. However, more data on spatial and temporal variation in SOC are needed to improve model calibration and validation.
Profile Analysis and Modeling of Reduced Tillage Effects on Soil Nitrous Oxide Flux
Authors: Venterea Rodney T. , Stanenas Adam J. 
Published: June 2008

AbstractThe impact of no‐till (NT) and other reduced tillage (RT) practices on soil to atmosphere fluxes of nitrous oxide (N2O) are difficult to predict, and there is limited information regarding strategies for minimizing fluxes from RT systems. We measured vertical distributions of key microbial, chemical, and physical properties in soils from a long‐term tillage experiment and used these data as inputs to a process‐based model that accounts for N2O production, consumption, and gaseous diffusion. The results demonstrate how differences among tillage systems in the stratification of microbial enzyme activity, chemical reactivity, and other properties can control N2O fluxes. Under nitrification‐dominated conditions, simulated N2O emissions in the presence of nitrite () were 2 to 10 times higher in NT soil compared to soil under conventional tillage (CT). Under denitrification‐dominated conditions in the presence of nitrate (), higher bulk density and water content under NT promoted higher denitrification rates than CT. These effects were partially offset by higher soluble organic carbon and/or temperature and lower N2O reduction rates under CT. The NT/CT ratio of N2O fluxes increased as or was placed closer to the surface. The highest NT/CT ratios of N2O flux (>30:1) were predicted for near‐surface placement, while NT/CT ratios < 1 were predicted for placement below 15 cm. These results suggest that N2O fluxes from RT systems can be minimized by subsurface fertilizer placement and by using a chemical form of fertilizer that does not promote substantial accumulation.
Avoided Deforestation as a Greenhouse Gas Mitigation Tool: Economic Issues
Authors: Sohngen Brent , Beach Robert H. , Andrasko Kenneth 
Published: June 2008

AbstractTropical deforestation is a significant contributor to accumulation of greenhouse gases (GHGs) in the atmosphere. GHG emissions from deforestation in the tropics were in the range of 1 to 2 Pg C yr−1for the 1990s, which is equivalent to as much as 25% of global anthropogenic GHG emissions. While there is growing interest in providing incentives to avoid deforestation and consequently reduce net carbon emissions, there is limited information available on the potential costs of these activities. This paper uses a global forestry and land use model to analyze the potential marginal costs of reducing net carbon emissions by avoiding deforestation in tropical countries. Our estimates suggest that about 0.1 Pg C yr−1of emissions reductions could be obtained over the next 30 to 50 yr for $5 per Mg C, and about 1.6 Pg C yr−1could be obtained over the same time frame for $100 per Mg C. In addition, the effects of carbon incentives on land use could be substantial. Relative to projected baseline conditions, we find that there would be around 3 million additional hectares (ha) of forestland in 2055 at $5 per Mg C and 422 million ha at $100 per Mg C. Estimates of reductions in area deforested, GHG mitigation potential, and annual land rental payments required are presented, all of which vary by region, carbon price paid, and time frame of mitigation.
Effect of Liquid Cow Manure on Andisol Properties and Atrazine Adsorption
Authors: Briceño Gabriela , Demanet Rolando , de la Luz Mora María , Palma Graciela 
Published: June 2008

AbstractApplication of animal manure amendments to agricultural soils is a common practice to improve soil fertility through the addition of essential plant nutrients. This practice may increase the potential for atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1, 3, 5‐triazine) leaching due to competition for adsorption sites between the pesticide and dissolved organic carbon (DOC) added through manure. We evaluated the influence of liquid cow manure (LCM) application on soil properties, atrazine adsorption, and the physicochemical controlling mechanisms in an Andisol. The LCM was applied at rates equivalent to 0, 100,000, 200,000, and 300,000 L ha−1, resulting in treatments S‐0, S‐100, S‐200, and S‐300, respectively. The LCM application increased DOC and pH of the soils immediately on addition, but pH returned to S‐0 values 30 d after application. The LCM application did not modify atrazine adsorption with the two lowest application rates (S‐100 and S‐200), but atrazine adsorption was decreased in S‐300 (Kf = 0.96) compared with the control (S‐0) (Kf = 1.19), possibly due to the competitive adsorption of DOC with the pesticide. The Fourier‐transformed infrared analysis showed that LCM increased aliphaticity and presence of N‐containing groups and polysaccharide‐like groups in amended soils; however, these properties did not modify the atrazine interaction in the studied amended soils. Interestingly the addition of DOC to soil at the high application rate (S‐300) reduced atrazine adsorption in this rich OM Andisol despite the LCM not raising the concentration of stable organic matter. The application of high rates of liquid manure containing DOC incurs an increased risk of pesticide leaching.
Effect of Sampling Frequency on Estimates of Cumulative Nitrous Oxide Emissions
Authors: Parkin Timothy B. 
Published: June 2008

AbstractIt is generally recognized that soil N2O emissions can exhibit pronounced day‐to‐day variations; however, measurements of soil N2O flux with soil chambers typically are done only at discrete points in time. This study evaluated the impact of sampling frequency on the precision of cumulative N2O flux estimates calculated from field measurements. Automated chambers were deployed in a corn/soybean field and used to measure soil N2O fluxes every 6 h from 25 Feb. 2006 through 11 Oct. 2006. The chambers were located in two positions relative to the fertilizer bands—directly over a band or between fertilizer bands. Sampling frequency effects on cumulative N2O–N flux estimation were assessed using a jackknife technique where populations of N2O fluxes were constructed from the average daily fluxes measured in each chamber. These test populations were generated by selecting measured flux values at regular time intervals ranging from 1 to 21 d. It was observed that as sampling interval increased from 7 to 21 d, variances associated with cumulative flux estimates increased. At relatively frequent sampling intensities (i.e., once every 3 d) N2O–N flux estimates were within ±10% of the expected value at both sampling positions. As the time interval between sampling was increased, the deviation in estimated cumulative N2O flux increased, such that sampling once every 21 d yielded estimates within +60% and −40% of the actual cumulative N2O flux. The variance of potential fluxes associated with the between‐band positions was less than the over‐band position, indicating that the underlying temporal variability impacts the efficacy of a given sampling protocol.
Managing Biosolids Runoff Phosphorus Using Buffer Strips Enhanced with Drinking Water Treatment Residuals
Authors: Wagner D. J. , Elliott H. A. , Brandt R. C. , Jaiswal D. 
Published: June 2008

AbstractVegetated buffers strips typically have limited ability to reduce delivery of dissolved phosphorus (DP) from agricultural fields to surface waters. A field study was conducted to evaluate the ability of buffer strips enhanced with drinking water treatment residuals (WTRs) to control runoff P losses from surface‐applied biosolids characterized by high water‐extractable P (4 g kg−1). Simulated rainfall (62.4 mm h−1) was applied to grassed plots (3 m × 10.7 m including a 2.67 m downslope buffer) surface‐amended with biosolids at 102 kg P ha−1 until 30 min of runoff was collected. With buffer strips top‐dressed with WTR (20 Mg ha−1), runoff total P (TP = 2.5 mg L−1) and total DP (TDP = 1.9 mg L−1) were not statistically lower (α = 0.05) compared to plots with unamended grass buffers (TP = 2.7 mg L−1; TDP = 2.6 mg L−1). Although the applied WTR had excess capacity (Langmuir P maxima of 25 g P kg−1) to sorb all runoff P, kinetic experiments suggest that sheet flow travel time across the buffers (∼30 s) was insufficient for significant P reduction. Effective interception of dissolved P in runoff water by WTR‐enhanced buffer strips requires rapid P sorption kinetics and hydrologic flow behavior ensuring sufficient runoff residence time and WTR contact in the buffer. Substantial phosphate‐adsorbent contact opportunity may be more easily achieved by incorporating WTRs into P‐enriched soils or blending WTRs with applied P sources.
Nutrient Dynamics and Tree Growth of Silvopastoral Systems: Impact of Poultry Litter
Authors: Blazier Michael A. , Gaston Lewis A. , Clason Terry R. , Farrish Kenneth W. , Oswald Brian P. , Evans Hayden A. 
Published: June 2008

AbstractFertilizing pastures with poultry litter has led to an increased incidence of nutrient‐saturated soils, particularly on highly fertilized, well drained soils. Applying litter to silvopastures, in which loblolly pine (Pinus taeda L.) and bahiagrass (Paspalum notatum) production are integrated, may be an ecologically desirable alternative for upland soils of the southeastern USA. Integrating subterranean clover (Trifolium subterraneum) into silvopastures may enhance nutrient retention potential. This study evaluated soil nutrient dynamics, loblolly pine nutrient composition, and loblolly pine growth of an annually fertilized silvopasture on a well drained soil in response to fertilizer type, litter application rate, and subterranean clover. Three fertilizer treatments were applied annually for 4 yr: (i) 5 Mg litter ha−1 (5LIT), (ii) 10 Mg litter ha−1 (10LIT), and (iii) an inorganic N, P, K pasture blend (INO). Litter stimulated loblolly pine growth, and neither litter treatment produced soil test P concentrations above runoff potential threshold ranges. However, both litter treatments led to accumulation of several nutrients (notably P) in upper soil horizons relative to INO and unfertilized control treatments. The 10LIT treatment may have increased N and P leaching potential. Subterranean clover kept more P sequestered in the upper soil horizon and conferred some growth benefits to loblolly pine. Thus, although these silvopasture systems had a relatively high capacity for nutrient use and retention at this site, litter should be applied less frequently than in this study to reduce environmental risks.
Integrating Contributing Areas and Indexing Phosphorus Loss from Agricultural Watersheds
Authors: Sharpley Andrew N. , Kleinman Peter J. A. , Heathwaite A. Louise , Gburek William J. , Weld Jennifer L. , Folmar Gordon J. 
Published: June 2008

AbstractMost states in the USA have adopted P Indexing to guide P‐based management of agricultural fields by identifying the relative risk of P loss at farm and watershed scales. To a large extent, this risk is based on hydrologic principles that frequently occurring storms can initiate surface runoff from fields. Once initiated, this hydrological pathway has a high potential to transport P to the stream. In regions where hydrologically active areas of watersheds vary in time and space, surface runoff generation by “saturation excess” has been linked to distance from stream, with larger events resulting in larger contributing distances. Thus, storm‐return period and P loss from a 39.5‐ha mixed‐land‐use watershed in Pennsylvania was evaluated to relate return‐period thresholds and distances contributing P to streams. Of 248 storm flows between 1997 and 2006, 93% had a return period of 1 yr, contributing 47% of total P (TP) export, while the largest two storms (10‐yr return period) accounted for 23% of TP export. Contributing distance thresholds for the watershed were determined (50–150 m) for a range of storm‐return periods (1−10 yr) from hydrograph analysis. By modifying storm‐return period thresholds in the P Index and thereby contributing distance, it is possible to account for greater risk of P loss during large storms. For instance, increasing return period threshold from 1 (current P indices) to 5 yr, which accounted for 67% of TP export, increased the P‐management restricted area from 20 to 58% of the watershed. An increase in impacted area relative to a decreased risk of P loss creates a management‐policy dilemma that cannot be ignored.
Improvement of Sand Filter and Constructed Wetland Design using an Environmental Decision Support System
Authors: Turon Clàudia , Comas Joaquim , Torrens Antonina , Molle Pascal , Poch Manel 
Published: June 2008

AbstractWith the aim of improving effluent quality of waste stabilization ponds, different designs of vertical flow constructed wetlands and intermittent sand filters were tested on an experimental full‐scale plant within the framework of a European project. The information extracted from this study was completed and updated with heuristic and bibliographic knowledge. The data and knowledge acquired were difficult to integrate into mathematical models because they involve qualitative information and expert reasoning. Therefore, it was decided to develop an environmental decision support system (EDSS‐Filter‐Design) as a tool to integrate mathematical models and knowledge‐based techniques. This paper describes the development of this support tool, emphasizing the collection of data and knowledge and representation of this information by means of mathematical equations and a rule‐based system. The developed support tool provides the main design characteristics of filters: (i) required surface, (ii) media type, and (iii) media depth. These design recommendations are based on wastewater characteristics, applied load, and required treatment level data provided by the user. The results of the EDSS‐Filter‐Design provide appropriate and useful information and guidelines on how to design filters, according to the expert criteria. The encapsulation of the information into a decision support system reduces the design period and provides a feasible, reasoned, and positively evaluated proposal.
Physical and Chemical Properties of Feedlot Pen Surfaces Located on Moderately Coarse– and Moderately Fine–Textured Soils in Southern Alberta
Authors: Miller Jim J. , Curtis Tony , Larney Francis J. , McAllister Tim A. , Olson Barry M. 
Published: June 2008

AbstractSouthern Alberta has the highest density of feedlot cattle in Canada, and there is a concern that leaching of water and contaminants may be greater for feedlots located on coarser‐textured than finer‐textured soils. Our objective was to determine if infiltration and leaching were greater for a 4‐yr‐old feedlot located on a moderately coarse–textured (MC) soil compared with two feedlots located on moderately fine–textured (MF) soils (5‐ and 52‐yr‐old pens). Various soil physical properties of feedlot pen surfaces were measured, including field‐saturated hydraulic conductivity (Kfs) and near‐saturated hydraulic conductivity at −0.9 and −3.9 cm water potential. Selected chemical properties of feedlot soil layers were measured, as well as the chloride content of the soil profile (0–100 cm). Mean Kfs, K(−0.9), and K(−3.9) values were not significantly (P > 0.10) greater at the MC site than the two MF sites, indicating no evidence of greater infiltration on coarser‐textured soils. In addition, mean Kfs, K(−0.9), and K(−3.9) values of soils within feedlot pens at all three sites were significantly (P ≤ 0.10) reduced by 46 to 78% compared with soil outside the pens. Depth of chloride accumulation was greatest at the 52‐yr‐old feedlot on MF soil (60–70 cm), followed by 4‐yr‐old feedlot on MC soil (40–50 cm) and 5‐yr‐old feedlot on MF soil (30–40 cm). Visual inspection determined that the black interface layer formed within 2 mo of cattle stocking at all three sites.
Greenhouse Gas Emissions from Two Soils Receiving Nitrogen Fertilizer and Swine Manure Slurry
Authors: Jarecki Marek K. , Parkin Timothy B. , Chan Alvarus S. K. , Hatfield Jerry L. , Jones Raymond 
Published: June 2008

AbstractThe interactive effects of soil texture and type of N fertility (i.e., manure vs. commercial N fertilizer) on N2O and CH4 emissions have not been well established. This study was conducted to assess the impact of soil type and N fertility on greenhouse gas fluxes (N2O, CH4, and CO2) from the soil surface. The soils used were a sandy loam (789 g kg−1 sand and 138 g kg−1 clay) and a clay soil (216 g kg−1 sand, and 415 g kg−1 clay). Chamber experiments were conducted using plastic buckets as the experimental units. The treatments applied to each soil type were: (i) control (no added N), (ii) urea‐ammonium nitrate (UAN), and (iii) liquid swine manure slurry. Greenhouse gas fluxes were measured over 8 weeks. Within the UAN and swine manure treatments both N2O and CH4 emissions were greater in the sandy loam than in the clay soil. In the sandy loam soil N2O emissions were significantly different among all N treatments, but in the clay soil only the manure treatment had significantly higher N2O emissions. It is thought that the major differences between the two soils controlling both N2O and CH4 emissions were cation exchange capacity (CEC) and percent water‐filled pore space (%WFPS). We speculate that the higher CEC in the clay soil reduced N availability through increased adsorption of NH4+ compared to the sandy loam soil. In addition the higher average %WFPS in the sandy loam may have favored higher denitrification and CH4 production than in the clay soil.
Greenhouse Gas Balance for Composting Operations
Authors: Brown Sally , Kruger Chad , Subler Scott 
Published: June 2008

AbstractThe greenhouse gas (GHG) impact of composting a range of potential feedstocks was evaluated through a review of the existing literature with a focus on methane (CH4) avoidance by composting and GHG emissions during composting. The primary carbon credits associated with composting are through CH4avoidance when feedstocks are composted instead of landfilled (municipal solid waste and biosolids) or lagooned (animal manures). Methane generation potential is given based on total volatile solids, expected volatile solids destruction, and CH4generation from lab and field incubations. For example, a facility that composts an equal mixture of manure, newsprint, and food waste could conserve the equivalent of 3.1 Mg CO2per 1 dry Mg of feedstocks composted if feedstocks were diverted from anaerobic storage lagoons and landfills with no gas collection mechanisms. The composting process is a source of GHG emissions from the use of electricity and fossil fuels and through GHG emissions during composting. Greenhouse gas emissions during composting are highest for high‐nitrogen materials with high moisture contents. These debits are minimal in comparison to avoidance credits and can be further minimized through the use of higher carbon:nitrogen feedstock mixtures and lower‐moisture‐content mixtures. Compost end use has the potential to generate carbon credits through avoidance and sequestration of carbon; however, these are highly project specific and need to be quantified on an individual project basis.
Treatment of Drainage Water with Industrial By‐Products to Prevent Phosphorus Loss from Tile‐Drained Land
Authors: McDowell R. W. , Sharpley A. N. , Bourke W. 
Published: June 2008

AbstractTile drained land with phosphorus (P)‐rich topsoil is prone to P loss, which can impair surface water quality via eutrophication. We used by‐products from steel and energy industries to mitigate P loss from tile drains. For each by‐product, P sorption maximum (Pmax) and strength (k) were determined, while a fluvarium trial assessed P uptake with flow rate. Although two ash materials (fly ash and bottom ash) had high Pmax and k values, heavy metal concentrations negated their use in the field. The fluvarium experiment determined that P uptake with by‐products was best at low flow, but decreased at higher flow in proportion to k. A mixture of melter slag (<10 mm) and basic slag (high Pmax, 7250 mg kg−1; and k, 0.508 L mg P−1) was installed as backfill in eight drains on a dairy farm. Four drains with greywacke as backfill were constructed for controls. The site (10 ha) had P‐rich topsoil (Olsen P of 64 mg kg−1) and yielded a mean dissolved reactive P (DRP) and total P (TP) concentration from greywacke backfilled drains of 0.33 and 1.20 mg L−1, respectively. In contrast, slag backfilled drains had DRP and TP concentrations of 0.09 and 0.36 mg L−1, respectively. Loads of DRP and TP in greywacke drains (0.45 and 1.92, respectively) were significantly greater (P < 0.05) than those from slag drains (0.18 and 0.85, respectively). Data from a farm where melter slag was used as a backfill suggested that slag would have a life expectancy of about 25 yr. Thus, backfilling tile drains with melter slag and a small proportion of basic slag is recommended as an effective means of decreasing P loss from high P soils.