bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some Aspects of Achieving Sustainable Phosphorus Use in Agriculture
Authors: Higgs B. , Johnston A. E. , Salter J. L. , Dawson C. J. 
Published: July 2010

AbstractThe management of P in agriculture must maximize the benefit to producers and minimize any adverse environmental effects. The latter arise from the loss of P from soil to standing freshwater. Even very small amounts of P can raise the concentration above the critical value for eutrophication. Such small quantities can be lost in eroded soil, in surface runoff and in drainage water. The relative importance of these pathways depends on many factors, including topography, rainfall, farming system, soil characteristics, and the bioavailability of the P that is lost. The success of agriculture in increasing food production to meet the increasing needs of humankind, especially since the 1950s, owes much to the use of P in fertilizers and animal feeds. What is now required is to ensure that P, a finite earth resource, is not wasted and that soils do not become so enriched with P that there is an unnecessary risk of too much P being carried to water from agricultural soils. The concept of taking account of critical soil P values to optimize the use of P in both fertilizer and manures is discussed here.
Development of an Indicator for Risk of Phosphorus Leaching
Authors: Hesketh N. , Brookes P. C. 
Published: July 2010

AbstractPrevious work showed that at soil P concentrations below 57 mg 0.5 M NaHCO3‐extractable P (Olsen P) kg−1 soil, little P was found in drainage waters collected from tile drains set 65 cm below the soil surface in soils from the Broadbalk Continuous Wheat Experiment. Above this soil P concentration (termed the Change‐Point) both total P and molybdate‐reactive P (MRP) in drainage waters were linearly related to soil Olsen P concentrations. We now need to know if the Change‐Point measured on Broadbalk occurs on other soils, and if so, whether a common value applies or if it varies depending upon soil type, management, and site hydrology. We investigated the possibility of 0.01 M CaCl2‐extractable P being an indicator of the Change‐Point. In all the soils studied, we found that the dynamics of P solubility in CaCl2 closely resembled the dynamics of P solubility in drainage waters of Broadbalk, since very distinct Change‐Points occurred under both conditions. However, Change‐Points measured following extraction with CaC2 varied widely between soils, from 10 to 119 mg Olsen P kg−1 soil. Lysimeter studies showed, with some exceptions, good agreement between Change‐Points measured in drainage water and in 0.01 M CaCl2. We therefore suggest that this approach may provide a valid indicator of the soil Olsen P concentration at which significant amounts of P begin to leach from soil to water, provided preferential pathways exist in the subsoil to permit P leaching down the soil profile in drainage water.
Assessing the Impact of Terrestrially Derived Phosphorus on Flowing Water Systems
Authors: Edwards A. C. , Twist H. , Codd G. A. 
Published: July 2010

AbstractRecent efforts to quantify the terrestrial inputs and cycling of P in agricultural systems are allowing management strategies to be developed to minimize the loss of P. While this approach has had clear advantages for standing waters, potential benefits for flowing freshwater systems are more difficult to predict. As a consequence of the unidirectional and dynamic nature of flow in rivers, temporal and spatial separations between the source of P and the point of potential impact arc introduced when considering a whole watershed. The ability to quantify the residence time of P within any particular part of a river system is therefore essential so that the specific contribution of individual P sources to biological demand can be determined. The smaller algal biomass productivity measured in flowing, compared with standing, waters at a similar supply rate of P indicates the need to consider the roles of other watershed factors in modifying the relationship between growth and P supply. The site‐specific nature of responses to P suggests a need to develop a hierarchical classification system where individual river sections can be ranked according to their likely responsiveness to P. The ecoregion concept, combined with stream order, would integrate spatial and temporal aspects of gradient, land use, flow velocity, and water quality. For this to be successful, we must demonstrate a link between perturbations to the terrestrial P cycle, the delivery of P to flowing waters, and a biological impact.
Buffer Zones and Constructed Wetlands as Filters for Agricultural Phosphorus
Authors: Uusi‐Kämppä Jaana , Braskerud Bent , Jansson Håkan , Syversen Nina , Uusitalo Risto 
Published: July 2010

AbstractFindings concerning P removal in buffer zones (BZs), constructed wetlands (CWs), and ponds in Finland, Norway, Sweden, and Denmark are presented in this paper because most such studies have been published only in Nordic languages. Retention of P was tested in 11 BZs, four CWs (less than 0.5‐m deep and vegetated with macrophytes), and seven ponds (deeper than 0.5 m). The grass buffer zone (GBZ) and vegetated buffer zone (VBZ) plots were compared with plots without a BZ; and P retention in CWs, ponds, and some BZs was estimated by subtracting total phosphorus (TP) mass in the outlet from TP mass in the inlet. Buffer zones decreased loads of TP from agricultural runoff water by 27 to 97% (0.24–0.67 kg ha−1 yr−1). The retention as a percentage increased with increasing BZ width. The BZ's upper part was, however, most effective in mitigating TP mass loads (1.6–4.4 g m−2), due to the importance of sedimentation as a retention process. The ponds and CWs reduced TP loads by 17 and 41%, respectively (2–116 g m−2 yr−1). The retention increased with the surface‐area/watershed‐area ratio. CWs were more effective in retaining TP than were ponds, possibly due to shallower depths and dense vegetation. The retention of dissolved reactive phosphorus (DRP) was inconsistent, both in BZs and in CWs. Vegetation should be harvested in BZs to decrease the DRP losses. Harvesting of vegetation is not recommended in CWs.
Prospects for Controlling Nonpoint Phosphorus Loss to Water: A UK Perspective
Authors: Withers Paul J. A. , Davidson Ian A. , Foy Robert H. 
Published: July 2010

AbstractAccelerated losses of P from intensively managed farmland can contribute to eutrophication problems in fresh waters, and improved nutrient and land management practices may be required in sensitive watersheds to help maintain good water quality for a range of users. Control of background P losses caused by increases in soil P status require long‐term strategies to reduce surplus P inputs, since excessive soil P accumulation cannot be rectified quickly. However, targeted actions aimed at controlling the transport of soil P, and/or preventing the often significant losses of P that occur following the application of fertilizers and manures to the land surface, are needed to achieve the more short‐term reductions in P export required to overcome the effects of eutrophication. The challenge is to identify which mitigation options can be implemented most cost‐effectively under the operating site hydrological conditions. Prospects for control of nonpoint P loss are discussed in relation to recent initiatives introduced in the UK where, in the absence of specific regulatory drivers for control, reductions in P loss must rely on voluntary actions taken collectively within the watershed. Integrated control strategies could be implemented, often at relatively low cost and/or with financial advantage to the farmer. Practical management tools are required to help stakeholders identify the key problem areas and avoid them through more precise nutrient and land management. Nutrient management remains a key issue since controls over manure P inputs, and the way they are handled, will have the greatest socioeconomic impact at a range of scales.
Sorption of Prochloraz on Primary Soil Organomineral Size Separates
Authors: de Jonge L. W. , de Jonge H. , Moldrup P. , Jacobsen O. H. , Christensen B. T. 
Published: July 2010

AbstractThe adsorption and desorption of the fungicide prochloraz (N‐propyl‐N‐[2‐(2,4,6‐trichlorophenoxy)‐ethyl]‐1‐H‐imidazol‐1‐carboxamid) to two whole soils and their sand, silt, and day‐size separates were investigated in batch experiments. The size separates were isolated using ultrasonic dispersion in water and repeated gravity sedimentation. For both soils, clay (<2 µm) and silt (2–20 µm) sorbed more prochloraz per kg of soil than did sand (20–2000 µm) and whole soil. Based on unit mass of organic matter, however, whole soils and size separates were equally effective adsorbers. On a unit surface area (BET N2) basis, the silt‐ and sand‐size separates were the most efficient sorbents. Adsorption and desorption isotherms, obtained after 1 and 24 h equilibration, were best described by the Freundlich model. Sorption‐desorption nonsingularity was observed for all size separates, and in general the degree of nonsingularity increased with contact time. Several sorption parameters were well correlated to soil organic C content and to particle porosity, the latter likely representing the pore volume available for diffusion of pesticide toward sorption sites. Adsorption kinetics and adsorption‐desorption nonsingularity could be well described by a two stage‐two rate model. Adsorption kinetics were characterized by a rapid initial adsorption with most of the pesticide being bound within 10 rain followed by a slow adsorption period. When using pesticide transport models that accounts for particle‐mediated transport, it is important to consider that the potentially mobile clay‐ and silt‐size separates typically have higher adsorption capacity than the average capacity of the whole soil.
Effects of Redox Conditions and Flow Processes on the Mobility of Dissolved Organic Carbon and Nitrogen in a Forest Soil
Authors: Hagedorn F. , Kaiser K. , Feyen H. , Schleppi P. 
Published: July 2010

AbstractIn forest ecosystems, organic solutes play prominent roles in pollutant and nutrient transport. This study, conducted in subalpine forested Humaquepts in Switzerland, investigated the influence of redox conditions and flow processes on dissolved organic carbon (DOC) and dissolved organic nitrogen (DON). In the mineral soil, concentrations of DOC were higher under reduced than under oxidized conditions. They averaged 1.2 mmol DOC L−1 in the reduced mineral soil at a 100‐cm depth. A close correlation between DOC and dissolved Fe concentrations (r2 = 0.83; p < 0.001) suggests that reductive dissolution of Fe‐oxides was the major reason for the low retention. However, during aerobic sampling of soil solution from the reduced mineral soil, DOC coprecipitated with Fe. This suggests that the DOC input from reduced mineral soils to aerobic stream water is lower than expected from the high DOC concentrations in the soil. Organic N was the major form of total dissolved N at all soil depths. In the reduced subsoil, dissolved N was completely organically bound. This was probably due to both an immobilization of inorganic N and a low retention of DON. During storms, DOC concentrations increased rapidly with increasing discharge in the subsurface flow. At peak flow, DOC concentrations were doubled, compared with base flow. The molar UV absorptivity of DOC in the subsurface flow corresponded closely to that of the topsoil. These findings suggest that DOC concentrations and properties are sensitive to flow velocities, and that DOC is preferentially transported to the subsoil at high discharge.
Plant‐Bacterial Combinations to Phytoremediate Soil Contaminated with High Concentrations of 2,4,6‐Trinitrotoluene
Authors: Siciliano Steven D. , Greer Charles W. 
Published: July 2010

AbstractThe explosive 2,4,6‐trinitrotoluene (TNT) is a contaminant of concern at abandoned manufacturing and military sites because of its mobility and toxicity. Phytoremediation may play a role in natural attenuation scenarios by reducing TNT levels at point sources. The purpose of this study was to develop a phytoremediation system suitable for use in soils contaminated with high TNT levels. Sixteen grasses were screened for their tolerance to 41 g TNT kg−1 soil. Meadow bromegrass (Bromus erectus Huds.), perennial ryegrass (Lolium perenne L.) and sweet vernalgrass (Anthoxanthum odoratum L.) grew in this soil. Inoculating these grasses with Pseudomonas sp. Strain 14, capable of transforming TNT into mono‐ and di‐amino metabolites, increased the growth of meadow bromegrass but was lethal to perennial ryegrass and sweet vernalgrass. Meadow bromegrass inoculated with Strain 14 reduced TNT levels by 30% compared with the control soil and had 50% more plant biomass than noninoculated plants. Meadow bromegrass, combined with Strain I4, increased the percentage of the culturable soil heterotrophic population containing the genes involved in 2‐nitrotoluene (ntdAa) metabolism 3‐fold, as well as the population containing the genes involved in 4‐nitrotoluene (ntnM) metabolism 14‐fold. Strain I4 inoculation of meadow bromegrass altered the portion of the rhizosphere community involved in nitroaromatic metabolism and led to a reduction in soil TNT levels.
Managing Nitrogen for Water Quality—Lessons from Management Systems Evaluation Area
Authors: Power J. F. , Wiese Richard , Flowerday Dale 
Published: July 2010

AbstractThe Management Systems Evaluation Area (MSEA) project was initiated in 1990 to evaluate existing and develop new N management technologies to reduce the potential adverse impacts of agricultural practices on surface and ground water quality. Field research sites were established in nine Midwestern states. Results from MSEA research showed that nitrate leaching was greatly reduced by changing from furrow to sprinkler irrigation. At least 95% of the nitrate N percolating through tiled soils was intercepted and discharged into surface waters. Computer models indicated that routing tile discharge through wetlands would greatly reduce the nitrate load. Nitrate losses also were reduced by establishing controlled water tables using drainage lines for subirrigation. Preplant and presidedress soil nitrate tests were effective in determining proper N fertilizer rates and reducing nitrate losses. Banding ammoniated fertilizers slowed nitrification rates and nitrate leaching, especially if soil over the bands was packed. A major new technology was proof that crop greenness can be used to monitor crop N sufficiency, and that N deficiencies after the V8 stage can be corrected by sidedressing or fertigation (reactive N management). Inexpensive sensors or aerial photographs can be used to assess crop greenness. Using Global Positioning Systems (GPS), N‐deficient areas of the field can be managed differently from the remainder of the field. These results point to the need to develop site‐specific or precision farming systems to control nitrate losses to water resources and reduce the impact of natural variability in both soils and weather.
Nitrapyrin Behavior in Soils and Environmental Considerations
Authors: Wolt Jeffrey D. 
Published: July 2010

AbstractUsing nitrification inhibitors is a well‐established fertilizer best management practice affording improved fertilizer use efficiency in crop production that may benefit profitability, crop quality, and the environment. The environmental benefit of nitrification inhibitor use in terms of managing N mobility in agroecosystems must be balanced against any environmental costs associated with the practice itself. Nitrapyrin exhibits multiple routes of degradation in the environment (hydrolysis, aerobic and anaerobic metabolism), which along with sorption and volatilization restrict its ability to mobilize to ground or surface water. Management practices (timing, rate, and method of application) that maximize nitrapyrin efficacy, additionally, favor the ultimate fate of nitrapyrin to occur by the linked processes of sorption and degradation within the upper soil profile. Thus, when nitrapyrin is used as a best management practice conducive of optimal fertilizer use efficiency, its environmental fate and behavior attributes minimize potential environmental exposure.
Nutrient Removal by Grasses Irrigated with Wastewater and Nitrogen Balance for Reed Canarygrass
Authors: Geber Ulrika 
Published: July 2010

AbstractTo develop complementary wastewater treatment systems that increase nutrient reduction and recycling, an experiment was conducted to evaluate the efficiency of three grass species as catch crops for N, P, and K at Surahammar wastewater treatment plant (WWTP) in the southern part of Sweden. Another objective was also to assess soil accumulation of N, P, and K and the risk of N leaching by drainage. Three grasses—reed canarygrass (Phalaris arundinacea L.), meadow foxtail (Alopecurus pratensis L.), and smooth bromegrass (Bromus inermis Leyss.)—were irrigated with a mixture of treated effluent and supernatant at two levels of intensity [optimum level (equal to evapotranspiration) and over‐optimal level] and at two nutrient levels, approximately 150 and 300 kg N ha−1. There were small differences in dry matter (DM) yield between grass species and no difference in N removal among species. The amount of N removed in harvested biomass to N applied was 0.58 in 1995 and 0.63 in 1996. The amount of N removed increased with increased nutrient load. Applied amounts of P were the same as P in harvested biomass. All species removed K amounts several times greater than applied amounts. Increased nutrient load increased overall K removal. The low amount of mineral N and especially NO−3‐N in the soil profile in autumn samplings indicate the risk for leaching is small. Soil water NO−3 contents were also low, <2.5 mg NO−3‐N L−1 during the growing season, with a mean value of <1 mg NO−3‐N L−1.
Application of Composted Pulp and Paper Mill Sludge to a Young Pine Plantation
Authors: Jackson M. J. , Line M. A. , Wilson S. , Hetherington S. J. 
Published: July 2010

AbstractDisposing of sludge recovered from the effluent stream of pulp and paper mills has traditionally involved landfilling. Shortages in landfill space and increasingly stringent environmental regulations in many countries have forced the industry to seek alternative disposal options. We assessed the feasibility of compost‐recycling a primary pulp and paper mill sludge (PMS) for use as a nutrient‐releasing mulch in plantation forestry. The effects of the composted PMS on the growth, nutrition, water relations, and weed suppression in a 3‐yr‐old plantation of radiata pine (Pinus radiata D.Don) on an infertile sandy soil in southern Tasmania were assessed. Compost was applied to the surface without incorporation in 0.5‐m wide bands in tree rows at rates of 0, 20, 40, and 60 metric t ha−1 (dry matter). One year after application of compost, the percentage increase in stem diameter was 40 to 66% greater than that achieved in untreated plots, with better growth at the highest compost application rate. Improved growth of radiata pine after application of compost was primarily attributable to a 17 to 37% increase in the concentration of foliar N and to decreased water stress in amended plots. Nitrogen released from the compost was mostly absorbed by plant roots within the first 20 cm of the soil profile, with no significant movement beyond this depth range. Application of compost prepared from PMS to young stands of radiata pine was found to be an acceptable recycling alternative for this material, capable of improving plantation productivity.
Comparison of Methods for Evaluating Stability and Maturity of Biosolids Compost
Authors: Wu L. , Ma L. Q. , Martinez G. A. 
Published: July 2010

AbstractCompost stability/maturity has become a critical issue for land application of compost because immature compost can be detrimental to plant growth and the soil environment. We compared several methods of evaluating the stability/maturity of biosolids compost: chemical properties, microbial respiration activity (CO2 evolution), seed germination tests, and dissolved organic carbon (DOC) as determined by its concentration and mass‐specific absorbence (MSA) at 420 nm. Two to five biosolids compost samples were collected during compost curing stages from three full‐scale composting facilities in Florida. The compost samples from two facilities were in the stabilization/maturation process. With curing time, electrical conductivity (EC), DOC concentration, and CO2 evolution rate decreased, whereas pH, seed germination rate, and the MSA of DOC increased in these samples. Compost samples from the third facility exhibited distinctly different behavior. Relatively high seed phytotoxicity, with no consistent trends of other parameters, suggested that these samples may have not been in a real curing process, despite the generally low CO2 evolution rate and DOC content. Based on these results, we concluded that pH, EC, CO2 evolution rate, seed germination rate, and DOC (concentration and MSA) could be used to monitor stabilization and maturation processes. Compost stability and maturity are different characteristics and both are needed for compost quality control. Dissolved organic carbon analysis is promising as a simple but comprehensive index for compost stability/maturity.
Zinc Uptake by Young Wheat Plants under Two Transpiration Regimes
Authors: Grifferty A. , Barrington S. 
Published: July 2010

AbstractTreated wastewater for crop irrigation is an alternative for countries with a shortage of fresh water. Such practice requires strict wastewater application criteria and a better understanding of the effects of transpiration rate on plant heavy metal uptake. The experiment measured Zn uptake by young wheat plants (Triticum aestivum L.) grown in triplicated experimental pots and held in two growth chambers with constant environmental conditions (relative humidity, light and temperature) but with a different air water vapor pressure deficit to produce two different transpiration rates. After 5 wk of growth in a greenhouse, the plants were transferred to the controlled chambers and irrigated using a fertilized solution with five different levels of Zn: 0, 2, 10, 25, and 50 mg/L. These Zn levels were low enough to have no significant effect on plant growth and transpiration rate. The wheat plants started to produce their grain at 6 wk. Plants were collected at 0, 3, and 10 d of incubation in the controlled chambers and analysed for dry matter and total Zn content. The pots were weighed daily to measure their transpiration rates. On Day 10, the remaining plants were collected and their roots, shoots, and grain were separated, weighed, dried, and analysed for total Zn. Time and plant transpiration rate were found to affect significantly plant Zn uptake. The higher transpiration rate enhanced plant Zn uptake. The roots had the highest Zn uptake followed by the shoots and then the grain.