Regulating manure application discharges from concentrated animal feeding operations in the United States

In the United States, reducing pollution from agriculture has received attention due to data suggesting that this is the leading source of impairment of many waterbodies. The federal government revised its regulations governing concentrated animal feeding operations (CAFOs) to enhance governmental oversight over sources of pollution. For the application of manure resulting in pollutant discharges, CAFOs need to implement nutrient management plans. A federal court affirmed the ability of the US federal government to oversee the application of manure from CAFOs that have discharges. Simultaneously, owners and operators of CAFOs who have implemented an appropriate nutrient management plan may forgo securing a permit if their discharges qualify under the agricultural stormwater discharge exemption.     

Water-extractable phosphorus in biosolids: implications for land-based recycling.

Phosphorus-based nutrient management will inevitably be required for land application of biosolids. Water-extractable phosphorus (WEP) in livestock manures is an indicator of phosphorus loss from agricultural watersheds and this study evaluated its use for biosolids. The WEP to total phosphorus percentage (PWEP) in 41 biosolids (representing a variety of wastewater and solids treatment processes) was compared to dairy and poultry manures and triple superphosphate fertilizer. The mean PWEP for conventionally treated and stabilized biosolids was 2.4%, which was significantly lower than inorganic fertilizer (85%), dairy manure (52%), and poultry manure (21%). Low biosolids PWEP is attributed to elevated aluminum and iron content from chemical additions during wastewater treatment and solids dewatering operations. Facilities using biological phosphorus removal had the highest mean biosolids PWEP (approximately 14%), whereas heat-dried biosolids had the lowest average PWEP (< approximately 0.5%). Paired samples of digested cake and the corresponding biosolids treated by processes to further reduce pathogens (i.e., thermal treatment, composting, and advanced alkaline stabilization) showed that these processes tended to reduce biosolids PWEP. Biosolids composition and processing mode exert a controlling influence on the potential for off-site phosphorus migration at land-application sites. Nutrient management policies for land-based recycling should account for the widely varying potential of organic amendments to cause soluble phosphorus losses in runoff and leaching.     

Surface water phosphorus dynamics in rice fields receiving fertiliser and manure phosphorus

A long-term randomised block field experiment was established in 1997 to study the dynamics of total P and dissolved P in the surface waters of rice fields receiving two application rates of fertiliser P and one rate of combined fertiliser and manure P. Preliminary results from the first two crops show that concentrations of both total P and dissolved P in the surface waters increased significantly following P application, especially during the first 2 weeks after application. P concentrations subsequently declined sharply within about 10 days, then declined steadily and remained almost constant from about 1 month after application. The initial increase in P concentration of surface waters was higher with increasing rate of fertiliser P, and the P concentration at the highest fertiliser rate peaked within about 1 week of application. The elevated P concentrations following fertiliser P application declined more rapidly than those following the combined application of fertiliser and manure P. When fertiliser and manure P were applied together, about 7 days later the surface water P concentrations were significantly higher than when the same rate of P (or double) was applied as fertiliser only. Disturbance of the surface soil by hand harrowing further increased the P concentrations in surface waters, with a subsequent decline to a steady value after about 1 week. Application of P fertiliser to the high P status soil in this experiment gave no crop yield response and may have increased the risk of pollution of adjacent surface waters through drainage from heavy rainfall events during the rice growing season. Therefore, fertiliser P should not be applied to such soils. If, however, fertiliser or manure P is applied, the application should be made during the dry winter to reduce P losses. Manure should be applied with particular care because of the higher risk of P losses to surface water arising from the relatively long period of high P concentrations in surface waters and the potential for greater release of P to field surface waters from the soil. Hand harrowing should also be avoided during wet weather to protect water quality.     

Nutrient losses by surface run-off following the application of organic manures to arable land. 1. Nitrogen

Research was conducted on nitrogen (N) surface run-off losses following organic manure applications to land, utilising a purpose-built facility on a sloping site in Herefordshire under arable tillage. Different rates and timing of cattle slurry, farmyard manure and inorganic N and phosphorus (P) fertiliser were compared, over a 4-year period (1993-97). P losses from the same studies are reported in a separate paper. The application of cattle slurries to the silty clay loam soil increased the loss of solids and NH4(+)-N in surface water flow compared to control plots receiving inorganic fertiliser only, or no treatment, but had little effect on NO3(-)-N losses by this route. Results were consistent with other observations that rainfall events immediately after manure applications are particularly likely to be associated with nutrient run-off losses. Losses via subsurface flow (30 cm interflow) were consistently much lower than via surface water movement and were generally unaffected by treatment. Increasing slurry application rate and, in particular, slurry solids loading, increased solids and NH4(-)-N losses via surface run-off. The threshold, above which the risk of losses via surface run-off appeared to be greatly increased, was ca. 2.5-3.0 t/ha slurry solids, which approximates to the 50 m3/ha limit suggested for slurry within UK 'good agricultural practice'. Sealing of the soil surface by slurry solids appears to be a possible mechanism by which polluting surface run-off may occur following slurry application on susceptible soils. Total losses of NH4(+)-N and NO3(-)-N during the 4-year monitoring period were insignificant in agronomic terms, but average soluble N concentrations (NH4(+)-N + NO3(-)-N) in run-off, ranging from ca. 2.0 mg/l, up to 14.0 mg/l for the higher rate slurry treatments. Peak concentrations of NH4(+)-N > 30 mg/l, are such as to be of concern in sensitive catchments, in terms of the potential for contribution to accelerated eutrophication and adverse effects on freshwater biota.     

Nutrient losses by surface run-off following the application of organic manures to arable land. 2. Phosphorus

Phosphorus (P) surface run-off losses were studied following organic manure applications to land, utilising a purpose-built facility on a sloping site in Herefordshire under arable tillage. Different rates and timing of cattle slurry, farm yard manure (FYM) and inorganic nitrogen (N) and P fertiliser were compared, over a 4-year period (1993-97). N losses from the same studies are reported in a separate paper. The application of cattle FYM and, especially slurry, to the silty clay loam soil increased both particulate and soluble P loss in surface water flow. Losses via subsurface flow (30 cm interflow) were consistently much lower than via surface water movement and were generally unaffected by treatment. Increased application of slurry solids increased all forms of P loss via surface run-off; the results suggested that a threshold for greatly increased risk of P losses via this route, as for N, occurred at ca. 2.5-3.0 t/ha solids loading. This approximates to the 50 m3/ha application rate limit suggested for slurry within UK 'good agricultural practice'. The studies also provided circumstantial evidence of the sealing of the soil surface by slurry solids as the major mechanism by which polluting surface run-off may occur following slurry application on susceptible soils. Losses of total and soluble P, recorded for each of the 4 years of experiments, reached a maximum of only up to 2 kg/ha total P (TP), even after slurry applications initiating run-off. Whilst these losses are insignificant in agronomic terms, peak concentrations of P (up to 30,000 micrograms/l TP) in surface water during a run-off event, could be of considerable concern in sensitive catchments. Losses of slurry P via surface run-off could make a significant contribution to accelerated eutrophication on entry to enclosed waters, particularly when combined with high concentrations of NO3(-)-N. Restricting slurry application rates to those consistent with good agronomic practice, and within the limits specified in existing guidelines on good agricultural practice, offers the simplest and most effective control measure against this potentially important source of diffuse pollution.     

Shallow groundwater quality on dairy farms with irrigated forage crops

California's dairies are the largest confined animal industry in the state. A major portion of these dairies, which have an average herd size of nearly 1000 animal units, are located in low-relief valleys and basins. Large amounts of liquid manure are generated and stored in these dairies. In the semi-arid climate, liquid manure is frequently applied via flood or furrow irrigation to forage crops that are grown almost year-round. Little is known about the impact of manure management practices on water quality of the extensive alluvial aquifers underlying these basins. The objective of this work is to assess nitrate and salt leaching to shallow groundwater in a relatively vulnerable hydrogeologic region and to quantify the impact from individual sources on dairies. The complex array of potential point and nonpoint sources was divided into three major source areas representing farm management units: (1) manure water lagoons (ponds); (2) feedlot or exercise yard, dry manure, and feed storage areas (corrals); and (3) manure irrigated forage fields (fields). An extensive shallow groundwater-monitoring network (44 wells) was installed in five representative dairy operations in the northeastern San Joaquin Valley, CA. Water quality (electrical conductivity, nitrate-nitrogen, total Kjehldahl nitrogen) was observed over a 4-year period. Nitrate-N, reduced nitrogen and electrical conductivity (EC, salinity) were subject to large spatial and temporal variability. The range of observed nitrate-N and salinity levels was similar on all five dairies. Average shallow groundwater nitrate-N concentrations within the dairies were 64 mg/l compared to 24 mg/l in shallow wells immediately upgradient of these dairies. Average EC levels were 1.9 mS/cm within the dairies and 0.8 mS/cm immediately upgradient. Within the dairies, nitrate-N levels did not significantly vary across dairy management units. However, EC levels were significantly higher in corral and pond areas (2.3 mS/cm) than in field areas (1.6 mS/cm) indicating leaching from those management units. Pond leaching was further inferred from the presence of reduced nitrogen in three of four wells located immediately downgradient of pond berms. The estimated minimum average annual groundwater nitrate-N and salt loading from manure-treated forage fields were 280 and 4300 kg/ha, respectively. Leaching rates for ponds are estimated to be on the order of 0.8 m/year, at least locally. Since manure-treated fields represent by far the largest land area of the dairy, proper nutrient management will be a key to protecting groundwater quality in dairy regions overlying alluvial aquifers.     

Evaluation of quick tests for phosphorus determination in dairy manures

Nutrients in animal manure are valuable inputs in agronomic crop production. Rapid and timely information about manure nutrient content are needed to minimize the risks of phosphorus (P) over-application and losses of dissolved P (DP) in runoff from fields treated with manure. We evaluated the suitability of a commercial hand-held reflectometer, a hydrometer, and an electrical conductivity (EC) meter for determining DP and total P (TP) in dairy manures. Bulk samples (n = 107) collected from farms across CT, MD, NY, PA, and VA were highly variable in total solids (TS) concentration, ranging from 11 to 213gL(-1), in suspensions' pH (6.3-9.2), and EC (6.2-53.3 dS m(-1)). Manure DP concentrations measured using the RQFlex reflectometer (RQFlex-DP(s)) were related to molybdate-reactive P (MRP(s)) concentrations as follows: RQFlex-DP(s) = 0.471 x MRP(s) + 1102 (r2 = 0.29). Inclusion of pH and squared-pH terms improved the prediction of manure DP from RQFlex results (r2 = 0.66). Excluding five outlier samples that had pH < or = 6.9 the coefficient of determination (r2) for the MRP(s) and RQFlex-DP(s) relationship was 0.83 for 95% of the samples. Manure TS were related to hydrometer specific gravity readings (r2 = 0.53) that were in turn related to TP (r2 = 0.34), but not to either RQFlex-DP or MRP. Relationships between suspensions' EC and DP or TP were non-significant. Therefore, the RQFlex method is the only viable option for on-site quick estimates of DP that can be made more robust when complemented with TS and pH measurements. The DP quick test can provide near real-time information on soluble manure nutrient content across a wide range of handling and storage conditions on dairy farms and quick estimates of potential soluble P losses in runoff following land applications of manure.     

Is the evaluation of “traditional” physicochemical parameters sufficient to explain the potential toxicity of the treated wastewater at sewage treatment plants?

Water scarcity is one of the most important environmental and public health problems of our century. Treated wastewater reuse seems to be the most attractive option for the enhancement of water resources. However, the lack of uniform guidelines at European and/or Mediterranean level leaves room for application of varying guidelines and regulations, usually not based on risk assessment towards humans and the environment. The benefits of complementing the physicochemical evaluation of wastewater with a biological one are demonstrated in the present study using Cyprus, a country with extended water reuse applications, as an example. Four organisms from different trophic levels were used for the biological assessment of the wastewater, namely, Pseudokirchneriella subcapitata, Daphnia magna, Artemia salina and Vibrio fischeri. The physicochemical assessment of wastewater based on “traditional” chemical parameters indicated that the quality of the wastewater complies with the limits set by the relevant national guidelines for disposal. The ecotoxicological assessment, however, indicated the presence of toxicity throughout the sampling periods and most importantly an increase of the toxicity of the treated wastewater during summer compared to winter. The resulting poor correlation between the physicochemical and biological assessments demonstrates that the two assessments are necessary and should be performed in parallel in order to be able to obtain concrete results on the overall quality of the treated effluent. Moreover, a hazard classification scheme for wastewater is proposed, which can enable the comparison of the data sets of the various parameters deriving from the biological assessment in a comprehensive way.     

Managing ammonia emissions from livestock production in Europe

Around 75% of European ammonia (NH(3)) emissions come from livestock production. Emissions occur at all stages of manure management: from buildings housing livestock; during manure storage; following manure application to land; and from urine deposited by livestock on pastures during grazing. Ammoniacal nitrogen (total ammoniacal-nitrogen, TAN) in livestock excreta is the main source of NH(3). At each stage of manure management TAN may be lost, mainly as NH(3), and the remainder passed to the next stage. Hence, measures to reduce NH(3) emissions at the various stages of manure management are interdependent, and the accumulative reduction achieved by combinations of measures is not simply additive. This TAN-flow concept enables rapid and easy estimation of the consequences of NH(3) abatement at one stage of manure management (upstream) on NH(3) emissions at later stages (downstream), and gives unbiased assessment of the most cost-effective measures. We conclude that rapid incorporation of manures into arable land is one of the most cost-effective measures to reduce NH(3) emissions, while covering manure stores and applying slurry by band spreader or injection are more cost-effective than measures to reduce emissions from buildings. These measures are likely to rank highly in most European countries.     

Healthcare waste management practice in the West Black Sea Region,Turkey: A comparative analysis with the developed and developing countries

The need for proper healthcare waste management has been a crucial issue in many developing countries as it is in Turkey. The regulation regarding healthcare wastes in Turkey was updated in 2005 in accordance with the European Union (EU) waste directives, but it still falls behind meeting the requirements of current waste treatment technologies. Therefore, this study aims to reveal deficiencies, inconsistencies, and improper applications of healthcare waste management in the western part of the Turkish Black Sea Region. In this study, it was revealed that nearly 1 million people live in the region, resulting in 5 million hospital admissions annually. All the healthcare waste produced (1000 tons yr^?1) is treated in an autoclave plant. However, treating some categories of healthcare wastes in autoclave units mismatches with the EU waste regulations, as alternative treatment technologies are not technically able to treat all types of healthcare wastes. A proper waste management system, therefore, requires an internal segregation scheme to divert these wastes from the main healthcare waste stream. The existing malpractice in the region could cause serious health problems if no measure is taken urgently. It is expected that healthcare waste management in the region and then all across Turkey will be improved with the significant deficiencies and inconsistencies pointed out in this research.

Implications:?In developed countries, specific rules and regulations have already been implemented along with the recommendations for handling of healthcare waste. However, in Turkey, these wastes are treated in autoclave units, which mismatches with the European Union waste regulations, as alternative treatment technologies are not technically capable to treat all types of healthcare wastes. The existing malpractice could cause serious health problems if no measure is taken urgently. The authors demonstrated the existing status of Turkish waste management and revealed deficiencies, inconsistencies, and improper applications in comparison with developed and developing nations to align Turkish practice to European Union requirements.     

EU Water Framework Directive and Stockholm Convention Can we reach the targets for priority substances and persistent organic pollutants?

Background, aim and scope  

Water is a renewable resource and acceptable quality is important for human health, ecological and economic reasons, but human activity can cause great damage to the natural aquatic environment. Managing the water cycle in a sustainable way is the key to protect natural resources and human health. On a global level, the microbiological contamination of water sources is a major problem in connection with poverty and the United Nations Millennium Development Declaration is an important initiative to handle this problem. In terms of environmental health, persistent organic pollutants (POPs) circulate globally; as they travel long distances, they are found in remote areas far from their original source of application and can cause damage wherever they move to. On a global scale, United Nations Environmental Programme (UNEP) issued the Stockholm Convention to reduce POPs; in the European Union (EU), one intention of the Water Framework Directive (WFD) is to reach the good chemical status of waters; beside these regulations, there are other directives in support of these goals. The aim of this paper is to discuss whether the Stockholm Convention and the WFD allows meeting the targets of protection of human and environmental health, which are established in the different directives and how could we approach the targets.     

Agricultural opportunities to mitigate greenhouse gas emissions

Agriculture is a source for three primary greenhouse gases (GHGs): CO(2), CH(4), and N(2)O. It can also be a sink for CO(2) through C sequestration into biomass products and soil organic matter. We summarized the literature on GHG emissions and C sequestration, providing a perspective on how agriculture can reduce its GHG burden and how it can help to mitigate GHG emissions through conservation measures. Impacts of agricultural practices and systems on GHG emission are reviewed and potential trade-offs among potential mitigation options are discussed. Conservation practices that help prevent soil erosion, may also sequester soil C and enhance CH(4) consumption. Managing N to match crop needs can reduce N(2)O emission and avoid adverse impacts on water quality. Manipulating animal diet and manure management can reduce CH(4) and N(2)O emission from animal agriculture. All segments of agriculture have management options that can reduce agriculture's environmental footprint.     

Phosphorus management in Europe in a changing world

Food production in Europe is dependent on imported phosphorus (P) fertilizers, but P use is inefficient and losses to the environment high. Here, we discuss possible solutions by changes in P management. We argue that not only the use of P fertilizers and P additives in feed could be reduced by fine-tuning fertilization and feeding to actual nutrient requirements, but also P from waste has to be completely recovered and recycled in order to close the P balance of Europe regionally and become less dependent on the availability of P-rock reserves. Finally, climate-smart P management measures are needed, to reduce the expected deterioration of surface water quality resulting from climate-change-induced P loss.     

Past,present, and future use of phosphorus in Chinese agriculture and its influence on phosphorus losses

Large inputs of phosphorus (P) in chemical fertilizers and feed supplements since 1978 have improved soil P status in arable land in China, but have also created challenges by increasing P concentrations in manure and exacerbating water quality degradation. Arable land in China can be divided into five management zones based on soil P chemistry, with 15–92 % of arable land having lower P status than the agronomic optimum and 0.3–7.2 % having severe risks of P leaching losses. A scenario analysis of soil P budget and agronomic P demand during 2011–2030 highlighted the great pressure China faces in sustainable P management and the need for drastic changes in current practices. This includes new policies to reduce P supplementation of feed and improved P use efficiency by livestock and programs to expand the adoption of appropriate fertilization, soil conservation, and drainage management practices to minimize P losses.     

Environmental transport of endogenous dairy manure estrogens

Although estrogens originating from dairy manure applied to agricultural soils as a fertilizer can potentially contaminate surface water and groundwater, the variables that control transport are poorly understood. Our objective was to assess the potential for off-site movement of endogenous dairy cattle estrogens when manure is applied on fields at agronomically relevant fertilization rates. Estrone (E1), 17α-estradiol (α-E2), and 17β-estradiol (β-E2) were used in laboratory sorption, desorption, and transformation incubations with both manure and an agriculturally relevant soil. Sorption on manure containing 44% organic carbon exceeded sorption on soil containing 0.8% organic carbon by 20 to 150 times, following the pattern of β-E2 > α-E2 > E1. Approximately 20% of E1 and 17% of α-E2 were desorbed from manure, whereas only about 4% of β-E2 was desorbed. Thirty to seventy percent of α-E2 and β-E2 were converted to E1 in soil and manure, making it imperative that transformation reactions be considered when predicting transport and potential biological effects in the environment. Overall results indicate that high organic carbon concentrations and relatively low amounts of desorption inhibit the potential for off-site transport of endogenous dairy manure estrogens.     

EU Water Framework Directive and Stockholm Convention

Background, aim and scope

Water is a renewable resource and acceptable quality is important for human health, ecological and economic reasons, but human activity can cause great damage to the natural aquatic environment. Managing the water cycle in a sustainable way is the key to protect natural resources and human health. On a global level, the microbiological contamination of water sources is a major problem in connection with poverty and the United Nations Millennium Development Declaration is an important initiative to handle this problem. In terms of environmental health, persistent organic pollutants (POPs) circulate globally; as they travel long distances, they are found in remote areas far from their original source of application and can cause damage wherever they move to. On a global scale, United Nations Environmental Programme (UNEP) issued the Stockholm Convention to reduce POPs; in the European Union (EU), one intention of the Water Framework Directive (WFD) is to reach the good chemical status of waters; beside these regulations, there are other directives in support of these goals. The aim of this paper is to discuss whether the Stockholm Convention and the WFD allows meeting the targets of protection of human and environmental health, which are established in the different directives and how could we approach the targets.

Materials and methods

The aims and scopes of different directives are compiled and compared with the actual quality of water, different approaches of standard settings are compared and potential treatment options are discussed.

Results

Under the Stockholm Convention on POPs, which came into force in May 2004, governments are required to develop a National Implementation Plan (NIP) setting out how they will address their obligations under the convention and how they will take measures to eliminate or reduce the release of POPs into the environment by the use of best available techniques (BAT) and application of best environmental practices (BEP). On a European level, the WFD has been in place as the main European legislation to protect our water resources and the water environment of Europe since 2000. It requires managing river basins so that the quality and quantity of water does not affect the ecological services of any specific water body. Nevertheless, the goals of other directives as for drinking water, bathing water and urban wastewater treatment are not yet harmonised mainly concerning microbiological, priority substances and priority hazardous substances (PS/PHS) contamination. Following the detection of substances, a risk assessment with sound effect data needs to be performed also for regulatory decisions and priorisation of measures to remove emerging contaminants. Beside personal care products and industrial contaminants, faecal pollution of recreational waters is one of the major hazards facing users, although microbial contamination from other sources as well as chemical and physical aspects also affects the suitability of water for recreation. As in arid and semiarid areas, wastewater is considered for irrigation with regulatory needs of hygienic and chemical parameters—health-based targets—to avoid the contamination of crops and food. In surface waters, currently, the relationships between physical and chemical properties and the biological state of surface waters were quite well-understood to enable the management of catchments and rivers to achieve ecological quality.

Discussion

Nevertheless, more work is needed to find out the actual impact of the regulations for single chemicals and complex mixtures, in terms of environmental quality standards to achieve a ‘good chemical status’, on the good biological status. In a next step after the adoption of the list of PS/PHS substances, which also includes the POPs, the Urban Wastewater Treatment Directive (UWWTD) needs to be adjusted and existing or new treatment options (BATs) should comply with the new requirements of the different directives.

Conclusions

Relevant substances threaten human health and the environment by new effects such as CMR, endocrine-disrupting effects or neurotoxicity which are not yet considered in an adequate way by assessment methods and regulatory standards and the application of abatement technologies. The Registration, Evaluation, Authorisation and Restriction of Chemicals helps to control the sources, but WFD, the Stockholm Convention and UWWTD need to be harmonised and a rolling revision process should react on new developments. Finally, to answer the question if the Stockholm Convention and the WFD (2000/60/EC) could reach the target—I would state that they provide a very valuable frame to approach the targets, but there is still way to go to reach them on an EU level and on a global scale, also under the aspects of the Stockholm Convention and the Millennium Development Goals.

Perspectives

The compilation of the goals of different regulations and combined actions will save a lot of administrative efforts and money.

     

Water safety plans as a tool for drinking water regulatory frameworks in Arctic communities

Arctic communities often face drinking water supply challenges that are unique to their location. Consequently, conventional drinking water regulatory strategies often do not meet the needs of these communities. A literature review of Arctic jurisdictions was conducted to evaluate the current water management approaches and how these techniques could be applied to the territory of Nunavut in Canada. The countries included are all members of the Arctic Council and other Canadian jurisdictions considered important to the understanding of water management for Northern Canadian communities. The communities in Nunavut face many challenges in delivering safe water to customers due to remoteness, small community size and therefore staffing constraints, lack of guidelines and monitoring procedures specific to Nunavut, and water treatment and distribution systems that are vastly different than those used in southern communities. Water safety plans were explored as an alternative to water quality regulations as recent case studies have demonstrated the utility of this risk management tool, especially in the context of small communities. Iceland and Alberta both currently have regulated water safety plans (WSPs) and were examined to understand shortcomings and benefits if WSPs were to be applied as a possible strategy in Nunavut. Finally, this study discusses specific considerations that are necessary should a WSP approach be applied in Nunavut.     

Quantifying phosphorus levels in soils, plants, surface water, and shallow groundwater associated with bahiagrass-based pastures

Background, aim, and scope  

Recent assessments of water quality status have identified eutrophication as one of the major causes of water quality ‘impairment’ not only in the USA but also around the world. In most cases, eutrophication has accelerated by increased inputs of phosphorus due to intensification of crop and animal production systems since the early 1990s. Despite substantial measurements using both laboratory and field techniques, little is known about the spatial and temporal variability of phosphorus dynamics across landscapes, especially in agricultural landscapes with cow-calf operations. Critical to determining environmental balance and accountability is an understanding of phosphorus excreted by animals, phosphorus removal by plants, acceptable losses of phosphorus within the manure management and crop production systems into soil and waters, and export of phosphorus off-farm. Further research effort on optimizing forage-based cow-calf operations to improve pasture sustainability and protect water quality is therefore warranted. We hypothesized that properly managed cow-calf operations in subtropical agroecosystem would not be major contributors to excess loads of phosphorus in surface and ground water. To verify our hypothesis, we examined the comparative concentrations of total phosphorus among soils, forage, surface water, and groundwater beneath bahiagrass-based pastures with cow-calf operations in central Florida, USA.     

Impacts of swine manure pits on groundwater quality

Manure deep-pits are commonly used to store manure at confined animal feeding operations. However, previous to this study little information had been collected on the impacts of deep-pits on groundwater quality to provide science-based guidance in formulating regulations and waste management strategies that address risks to human health and the environment. Groundwater quality has been monitored since January 1999 at two hog finishing facilities in Illinois that use deep-pit systems for manure storage. Groundwater samples were collected on a monthly basis and analyzed for inorganic and bacteriological constituent concentrations. The two sites are located in areas with geologic environments representing different vulnerabilities for local groundwater contamination. One site is underlain by more than 6 m of clayey silt, and 7-36 m of shale. Concentrations of chloride, ammonium, phosphate, and potassium indicated that local groundwater quality had not been significantly impacted by pit leakage from this facility. Nitrate concentrations were elevated near the pit, often exceeding the 10 mg N/l drinking water standard. Isotopic nitrate signatures suggested that the nitrate was likely derived from soil organic matter and fertilizer applied to adjacent crop fields. At the other site, sandstone is located 4.6-6.1 m below land surface. Chloride concentrations and delta15N and delta15O values of dissolved nitrate indicated that this facility may have limited and localized impacts on groundwater. Other constituents, including ammonia, potassium, phosphate, and sodium were generally at or less than background concentrations. Trace- and heavy-metal concentrations in groundwater samples collected from both facilities were at concentrations less than drinking water standards. The concentration of inorganic constituents in the groundwater would not likely impact human health. Fecal streptococcus bacteria were detected at least once in groundwater from all monitoring wells at both sites. Fecal streptococcus was more common and at greater concentrations than fecal coliform. The microbiological data suggest that filtration of bacteria by soils may not be as effective as commonly assumed. The presence of fecal bacteria in the shallow groundwater may pose a significant threat to human health if the ground water is used for drinking. Both facilities are less than 4 years old and the short-term impacts of these manure storage facilities on groundwater quality have been limited. Continued monitoring of these facilities will determine if they have a long-term impact on groundwater resources.     

Nutrient run-off following application of livestock wastes to grassland

Three types of farm waste (cattle slurry, dirty water and farm yard manure (FYM)) were applied to hydrologically isolated grassland plots on a sloping poorly draining soil. Two applications were made, the first in October and the second in February. Application rates were 50 m(3) ha(-1) of slurry and dirty water and 50 t ha(-1) of FYM. Volumes of run-off following rainfall events and concentrations of N, P and K in run-off were measured. Losses of nutrients were higher following applications made with the soil at field capacity and rainfall soon after application. In terms of percentage loss of applied nutrients, losses were generally low. Concentration of N in run-off from the dirty water and FYM treated plots following the first application and the slurry treated plots following the second application exceeded 11.3 mg dm(-3) (a recommended limit for drinking water) although the maximum concentration recorded was 15 mg dm(-3) following FYM application. Concentration of P in run-off only exceeded 1 mg dm(-3) following the second application of cattle slurry. Concentration of K exceeded 10 mg dm(-3) following the first application of FYM and the second application of cattle slurry.