Diet modification to reduce phosphorus surpluses: a mass balance approach

Diet modification to reduce phosphorus (P) concentrations in manures has been developed in response to environmental concerns over P losses from animal agriculture to surface waters. We used USDA-NASS statistics on animal numbers and crop production to calculate county scale mass balances for manure P production, P removed in harvested portion of crops, and the potential effects of diet modification. Although spreading manure evenly over all crop acreage within a county is unlikely to occur, these calculations give a good indication as to the impact diet modification to reduce P can have at a regional or national scale. There was a high degree of regional variability in manure P surpluses (e.g., with the large crop acreages in the grain belt leading to large P offtake in crops preventing most P surpluses). In 89% of counties, there was a deficit of manure P relative to crop P removal; therefore there was a manure P surplus in 11% of counties. Diet modification decreased the percentage of states with a manure P surplus from 11 to 8%, a decrease of approximately 27%. Diet modification decreased the percentage of counties with the greatest surpluses of manure P (>30 kg ha(-1)) from 3% of all counties to 1%. Diet modification to decrease manure P is an important part of strategies to alleviate environmental concerns associated with surplus manure P in many areas, but additional strategies to deal with manure P surpluses are needed in some areas.     

A PRELIMINARY ANALYSIS OF ANIMAL MANURE DISTRIBUTION IN MICHIGAN FOR NUTRIENT UTILIZATION1

ABSTRACT: Proper management of animal manure is crucial to the viability of the U.S. animal industry and the quality of the environment. This paper analyzes the animal manure distribution in Michigan, identifies counties with high potential for land application of manure nutrients, and proposes a manure distribution prototype model for transporting surplus manure beyond individual farms for nutrient utilization. Tabulations of animal numbers by county and by 5-digit zip code are used to identify areas with greater potential for land application of manure nutrients. Distribution of the manure nutrients from surplus areas to the nutrient utilization areas is explored in a selected watershed by taking into account manure nutrient value, soil nutrient content, crop nutrient needs, topography and hydrography. The results indicate that by appropriate planning and collaboration transport of the excessive animal manure to suitable crop fields is an appealing alternative to utilize the manure nutrients while minimizing the adverse environmental impact. Further studies are needed to determine the necessary economic and institutional programs to implement the export of the manure at the regional level.     

Phosphorus accumulation in cultivated soils from long-term annual applications of cattle feedlot manure

Historically, manure has been recognized as an excellent soil amendment that can improve soil quality and provide nutrients for crop production. In areas of high animal density, however, the potential for water pollution resulting from improper storage or disposal of manure may be significant. The objective of this study was to determine the P balance of cultivated soils under barley (Hordeum vulgare L.) production that have received long-term annual manure amendments. Nonirrigated soils at the study site in Lethbridge, AB, Canada, have received 0, 30, 60, or 90 Mg manure ha(-1) (wet wt. basis) while irrigated plots received 0, 60, 120, and 180 Mg ha(-1) annually for 16 yr. The amount of P removed in barley grain and straw during the 16-yr period was between 5 and 18% of the cumulative manure P applied. There was a balance between P applied in manure and P recovered in crops and soils (to the 150-cm depth) of nonirrigated plots during the 16-yr study. In irrigated plots, as much as 1.4 Mg P ha(-1) added (180 Mg ha(-1) yr(-1) treatment) was not recovered over 16 yr, and was probably lost through leaching. The risk of ground water contamination with P from manure was greater in irrigated than nonirrigated plots that have received long-term annual manure amendments. Manure application rates should be reduced in nonirrigated and irrigated plots to more closely match manure P inputs to crop P requirements.     

Potential environmental benefits of ionophores in ruminant diets

A concern of the USEPA is the volatilization of NH3 from animal manure and CH4 produced from ruminal fermentation. Excess N in the environment has been associated with adverse effects on human health, and CH4 and N2O emissions are sources of greenhouse gases. The objectives of this paper are to summarize and quantify the benefits of ionophores, principally monensin, in decreasing NH3 and CH4 emissions to the environment and reducing resource utilization in cattle (Bos spp.) production. The data indicate that monensin in the diets of ruminants may decrease protein degradation in the rumen and may increase feed protein utilization by an average of 3.5 percentage units. These changes would have an effect in reducing N losses and decreasing fecal N and the amount of protein that must be fed to meet animal requirements. Additionally, CH4 is produced by enteric fermentation in ruminants, which is responsible for about 33 to 39% of CH4 emissions from agriculture. Ionophores can reduce CH4 production by 25% and decrease feed intake by 4% without affecting animal performance. The inclusion of monensin in beef and dairy cattle diets may benefit air quality by reducing CH4 and N emissions and water quality by reducing N in manure, which can potentially leave the farm through leaching into ground water and through runoff into surface water.     

Enzymatic characterization of organic phosphorus in animal manure

Information on the forms of P present in animal manure may improve our ability to manage manure P. In most investigations of manure P composition, only inorganic and total P are determined, and the difference between them is assigned as organic P. In this study, we explored the possibility of identifying and quantifying more specific organic P forms in animal manure with orthophosphate-releasing enzymes. Pig (Sus scrofa) manure and cattle (Bos taurus) manure were first sequentially fractionated into water-soluble P, NaHCO3-soluble P, NaOH-soluble P, HCl-soluble P, and residual P. The fractions were separately incubated with wheat phytase, alkaline phosphatase, nuclease P1, nucleotide pyrophosphatase, or their combinations. The released orthophosphate was determined by a molybdate blue method. Part of the organic P in those fractions could be identified by the enzymatic treatments as phytate (i.e., 39% for pig manure and 17% for cattle manure in water-soluble organic P), simple phosphomonoesters (i.e., 43% for pig manure and 15% for cattle manure in NaOH-soluble organic P), nucleotide-like phosphodiesters (2-12%), and nucleotide pyrophosphate (0-4%). Our data indicate that the enzymatic treatment is an effective approach to identify and quantify the organic P forms present in animal manures.     

Evaluating livestock system environmental performance with whole-farm nutrient balance

As a part of the USEPA's concentrated animal feeding operation (CAFO) final rule, all CAFOs are required to develop and implement a nutrient management plan (NMP). The USEPA's emphasis on better management of nutrients appropriately targets a critical environmental issue associated with animal production. The concentration of animals in livestock feeding operations, often separate from feed grain production, requires importing of substantial quantities of feed nutrients. Due to the inefficiencies of nutrient utilization in livestock production, quantities of nitrogen (N) and phosphorus (P) in manure greater than can be utilized in local crop production often result. With the focus of the USEPA's NMP rules on internal farm manure management planning, nutrient concentrations resulting from animal concentration may not be adequately addressed by compliance with the USEPA rules alone. A review of two mandatory and two voluntary nutrient management strategies is made by comparing whole-farm nutrient balance for a case-study beef cattle feedlot. The results suggest that voluntary BMPs, such as modification to animal feeding program and exporting of manure, can have greater environmental benefits (30-60% reduction in P accumulation for case-study farm) than mandatory NMPs and buffers (5-7% reduction in P accumulation for case-study farm) for a typical beef cattle feedlot. Whole-farm nutrient balance procedures can also be valuable for reviewing the nutrient performance of livestock systems.     

Farmers Under Pressure. Analysis of the Social Conditions of Cases of Animal Neglect

In this paper we analyse how risk factors in highly industrialised agriculture are connected to animal neglect. With Danish agriculture as a case study, we use two types of data. First, we use register data from Statistics Denmark to map how risk factors such as farmers’ financial and social troubles are connected to convictions of neglect. Second, we analyse narratives where interviewed farmers, involved in cases of neglect, describe how they themselves experienced the incidents. We find that while livestock farmers in general have a low risk of animal neglect problems, a small percentage of them face severe financial difficulties, divorce and psychiatric problems, which are connected to an increased risk of being convicted for the neglect of farm animals. The narratives bring forward themes of pressure related to financial trouble, technological break down, family problems, stress and a growing concern among the farmers towards the governmental control in farm animal production. We discuss how these factors can be used to identify and help farmers with a high risk of being convicted of livestock neglect.     

Pathogen survival in swine manure environments and transmission of human enteric illness--a review

The influence of zoonotic pathogens in animal manure on human health and well-being as a direct or indirect cause of human enteric illness is examined. Available international data are considered, but the study is focused on the developing situation in western Canada, where it is certain there will be further rapid growth in livestock numbers, particularly hogs. Major pathogens considered are Escherichia coli O157:H7, Salmonella, Campylobacter, Yersinia, Cryptosporidium, and Giardia. Canada is now the leading exporter of pork internationally, but recent increases in production contrast with constant domestic levels of pork consumption and declining levels of foodborne illness caused by pork. Effects of increased levels of manure production are not quantifiable in terms of effects on human health. The presence of major pathogens in manure and movement to human food sources and water are considered on the basis of available data. Survival of the organisms in soil, manure, and water indicate significant variability in resistance to environmental challenge that are characteristic of the organisms themselves. Generally, pathogens survived longer in environmental samples at cool temperatures but differences were seen in liquid and solid manure. Based on actual data plus some data extrapolated from cattle manure environments, holding manure at 25 degrees C for 90 d will render it free from the pathogens considered above.     

Feedlot Biomass Co-firing: A Renewable Energy Alternative for Coal-fired Utilities

The swiftly growing feedlot industry in the United States upshots in the production of manure from one or more animal species in excess of what can safely be applied to farmland, in accordance with nutrient management plans. Disposal of the vast quantity of manure produced as a by-product of the cattle feeding industry is one of the major operating tasks of the industry. Aside from the traditional means of disposal as fertilizer, an alternative and attractive way of overcoming this threat is to develop processes that make use of manure as an energy resource. In the present study, the feasibility of using manure as a fuel in existing coal fired power plants is considered and appropriately termed Feedlot Biomass (FB). The technology of co-firing coal: feedlot biomass facilitates an environment friendly utilization of animal waste for the production of valuable power/steam concurrently addressing the renewable energy, groundwater contamination, and greenhouse gas concerns. Co-firing tests were performed at the Texas A&M University 30 kW_t (100,000 Btu/h) laboratory-scale facility. The trials revealed the enhanced combustion of the blends. The NO emissions were less for the blend even with higher nitrogen content of FB, as compared to coal.     

日照市畜牧业生产对环境的污染及其防治措施研究

畜禽粪便中大量有机污染物污染着人们赖以生存的土壤和水体,粪尿分解产生的大量有害气体污染了大气。本文结合日照市畜牧业生产的实际,对日照市畜牧业生产对环境的污染现状进行了分析,找出了日照市畜牧业生产对环境污染产生的主要原因和存在问题,提出畜牧业生产对环境污染的防治对策。     

Manure collection and distribution on Wisconsin dairy farms

Manure management plans require knowing the amount of manure produced, collected, and available for land-spreading. Whereas much information is available to calculate manure production, little is known about the types and amounts of manure actually collected on typical dairy farms. This study of 54 representative Wisconsin dairy farms showed significant regional, housing, and herd size differences in collection of manure from lactating cows (Bos taurus), dry cows, and heifers. Significantly (P < 0.05) less manure is collected in the hilly southwest (56% of total annual herd production) than in the undulating south central (72%) or the flat northeast (68%) regions. Collection of lactating cow manure is significantly (P < 0.05) lower from stanchion (66% of total annual production) than free-stall (89%) housing, and significant (P < 0.05) positive relationships were found between the number of lactating cows a farm keeps and the percentage manure collected. Average annual manure N (range of 116-846 kg N ha(-1)) and P (range of 24-158 kg P ha(-1)) loading rates in areas where manure goes uncollected was highest in unvegetated barnyards followed by vegetated and partially vegetated outside areas. Once uncollected manure was accounted for, average annual loading rates on cereal cropland ranged from 128 to 337 kg ha(-1) of manure N, and from 45 to 139 kg ha(-1) of manure P. Compared with adjacent cropland, the accumulation of uncollected manure has vastly increased soil test P, K, and organic matter levels in outside areas. Manure management on Wisconsin dairy farms with small to medium herds might require assistance in managing manure in outside confinement areas to reduce the risk of impairing surface and ground water quality.     

Nitrous oxide emissions respond differently to mineral and organic nitrogen sources in contrasting soil types

The use of various animal manures for nitrogen (N) fertilization is often viewed as a viable replacement for mineral N fertilizers. However, the impacts of amendment type on NO production may vary. In this study, NO emissions were measured for 2 yr on two soil types with contrasting texture and carbon (C) content under a cool, humid climate. Treatments consisted of a no-N control, calcium ammonium nitrate, poultry manure, liquid cattle manure, or liquid swine manure. The N sources were surface applied and immediately incorporated at 90 kg N ha before seeding of spring wheat ( L.). Cumulative NO-N emissions from the silty clay ranged from 2.2 to 8.3 kg ha yr and were slightly lower in the control than in the fertilized plots ( = 0.067). The 2-yr mean NO emission factors ranged from 2.0 to 4.4% of added N, with no difference among N sources. Emissions of NO from the sandy loam soil ranged from 0.3 to 2.2 kg NO-N ha yr, with higher emissions with organic than mineral N sources ( = 0.015) and the greatest emissions with poultry manure ( < 0.001). The NO emission factor from plots amended with poultry manure was 1.8%, more than double that of the other treatments (0.3-0.9%), likely because of its high C content. On the silty clay, the yield-based NO emissions (g NO-N kg grain yield N) were similar between treatments, whereas on the sandy loam, they were greatest when amended with poultry manure. Our findings suggest that, compared with mineral N sources, manure application only increases soil NO flux in soils with low C content.     

Geographic information system based manure application plan

A geographic information system (GIS) based manure application plan has been developed for the site-specific application of animal waste to agricultural fields in the Westbrook sub-catchment of the Murray-Darling Basin, south-east Queensland, Australia. Sites suitable for animal waste application were identified using a GIS based weighted linear combination (WLC) model. The degree of land suitability for animal waste application was determined using a range of social, economic, environmental, and agricultural factors. As eutrophication and toxic blue-green algae blooms are a known problem in the catchment, the manure application rates were limited to the rate of crop phosphorus removal. Maximum manure application rate was calculated spatially by taking the crop nutrient (P2O5) requirement and the manure nutrient (P2O5) content into account. The environmental suitability of the fields receiving animal waste was considered in prescribing the final application rate of solid and liquid manures generated by local animal production facilities. The degree of site suitability of the agricultural fields was also used to suggest manure management practices to minimise the socio-environmental risks and increase the nutrient use efficiency of the applied manure. The amount of ammonium nitrogen (NH4-N) that would be added to the soil by satisfying the P2O5 requirement using manure sources was also calculated and an applied NH4-N map was created. This map could be used to assist farmers identify additional nitrogen requirements after manure application.     

Closing the phosphorus loop in England: The spatio-temporal balance of phosphorus capture from manure versus crop demand for fertiliser

Every year 90 million tonnes of housed livestock manures are produced in the UK. This is a valuable reservoir of global phosphorus (P) and a point in the cycle where it is vulnerable to being lost from the terrestrial system. Improved manure management for the effective reuse of phosphorus is vital to simultaneously tackle a major source of water pollution and reduce our dependence on imported fertilisers. This paper quantifies, for the first time, the spatial and temporal challenges of recycling the required amount of manure P from areas of livestock production to areas of crop production in eight regions of England. The analysis shows that England has a P deficit and therefore the capacity to fully utilise the manure P on arable land, but that uneven spatial distribution of livestock poses a significant challenge to closing the P loop in agriculture. Two of the eight regions were shown to have surplus manure P, with the remaining six regions having P deficits, indicating that an annual export of 4.7 thousand tonnes P (2.8 million tonnes manure) must take place from the west to the east of the country each year to balance P supply and demand. Moreover, housed manure production peaks between October and February, requiring an excess of 23.0 thousand tonnes P (15 million tonnes manure) to be stored until it can be used for crop fertilisation from March onwards. The results demonstrate the scale of the challenge in managing manure P in an agricultural system that has separated livestock production from crop production, a pattern that is echoed throughout the developed world. To overcome the spatial and temporal challenges, a logistical system is recommended that will balance the nutrient potential (nitrogen and P content and availability) and pollution potential (eutrophication, greenhouse gas emissions, particulates and nitrous oxide from transport) for cost-effective and environmentally compatible redistribution of manure P from areas of surplus to areas of deficit, when required.     

An assessment of nitrogen-based manure application rates on 39 U.S. swine operations

Water quality concerns and revised regulations are changing how confined animal feeding operations manage manure. Devising acceptable and feasible changes in manure practices requires a full understanding of the forces shaping current manure management decisions. Previous theoretical models have shown that a wide range of factors influence the lowest cost solution for manure management. We used a mechanistic model to characterize the manure management practices on 39 swine operations (20 unagitated lagoon and 19 slurry operations) in five states (Iowa, Missouri, North Carolina, Oklahoma, and Pennsylvania). Information was collected from each operation about animal numbers, feed and water use, manure handling and storage characteristics, field locations, crop rotation, fertilizer need, and equipment inventory and usage. Collected data were used as input and to validate results from a mechanistic model that determined acres required for manure application, manure application rate, time required for manure application, value of manure, and costs of manure management. The 39 farms had a mean of 984 animal units (AU) per operation, 18.2 AU ha(-1) (7.4 AU acre(-1)), and manure application costs of dollar 10.49 AU(-1) yr(-1). Significant factors affecting manure management included operation size, manure handling system, state, and ownership structure. Larger operations had lower manure management costs (r2 = 0.32). Manure value potentially exceeded manure application costs on 58% of slurry and 15% of lagoon operations. But 38% of slurry operations needed to apply manure off the farm whereas all lagoon operations had sufficient land for N-based manure management. Manure management was a higher percentage of gross income on contract operations compared with independents (P < 0.01). This research emphasized the importance of site-specific factors affecting manure management decisions and the economics of U.S. swine operations.     

A Sensitivity Analysis of Nitrogen Losses from Dairy Farms

International attention has focused on agricultural production systems as non-point sources of pollution affecting the quality of streams, estuaries and ground water resources. The objective of the current study was to develop a model of nitrogen management on the dairy farm, and to perform sensitivity analyses in order to determine the relative importance of manipulating herd nutrition, manure management and crop selection in reducing nitrogen (N) losses from the farm. The importance of the method of N input to the farm (purchased feed, legume fixation, inorganic fertilizer, imported manure) was investigated, and the potential to reduce N losses from dairy farms was evaluated. Nitrogen balance equations were derived, and related efficiency coefficients were set to reference values representing common management practices. Total farm N efficiency (animal product N per N input), and N losses per product N were determined for different situations by solving the set of simultaneous equations. Improvements in animal diet and management that increase the conversion of feed N to animal product by 50% would increase total farm N efficiency by 48% and reduce N losses per product by 36 to 40%. In contrast, reducing losses from manure collection, storage and application to improve the percentage of manure N that becomes available in soil by 100% would only improve total farm N efficiency by 13% and reduce total N losses by 14%. Selecting crops and management that can use soil nutrients 50% more efficiently would improve total farm efficiency by up to 59% and reduce N losses by up to 41% depending on the predominant nitrogen sources to the farm. Legume production would reduce N losses per product compared with non-legumes. There was more than a five fold difference in N losses per animal product N between the most extreme scenarios suggesting considerable opportunity to reduce N losses from dairy farms.     

Evolving policies to regulate pollution from animal feeding operations

Due to concentrations of animals at large facilities, animal feeding operations (AFOs) have emerged as a major potential source of water pollution. The federal government regulates concentrated animal feeding operations under its point-source pollution permitting regulations. A major determinant of whether an operation must apply for a permit is the number of animals at an individual lot or facility. This paper examines federal mandatory controls and voluntary guidelines that seek to reduce contaminant pollution from AFOs. Land treatment practices are delineated due to their importance in reducing the injurious by-products of agricultural production. An evaluation of proposed revisions to federal regulations on confined animal feeding operations suggests they diverge from their goal of controlling water pollution. Federal regulations focus on the size of operation and amount of manure governed by the permitting process to the exclusion of other criteria related to the impairment of water quality. Given the uncertainties about the amount of pollution from AFOs, lack of enforcement of existing regulations, localization of problems, and possible alternatives for addressing the pollution, more demanding federal regulations may not form an appropriate response.     

Poverty and biodiversity in rural areas based on two investigations in Pujiang County,China

This study presents an integrated framework for the analysis of options of agricultural development and natural resource management at the ecosystem level. Pujiang County in Zhejiang Province, China, is used as a case-study area. The IMGLP model is applied to maximize regional agricultural economic surplus and labor market conditions in Pujiang. The consequences of four poverty reduction strategies (intensification of production, diversification toward livestock production, land expansion, and exit from agriculture) are determined for a set of regional poverty and biodiversity indicators. Diversification seems to be the most promising poverty reduction strategy, but requires an efficient use of animal manure in cropping systems to avoid environmental problems. Improved nutrient management in cropping systems is effective in reducing the regional nitrogen surplus, but less effective in increasing per capita income. The exit strategy is beneficial for reducing poverty and achieving biodiversity, but may have important social consequences that are not addressed in this study. Further reduction of rural poverty is hampered by labor constraints during the harvesting period for high-value crops such as vegetables and fruits. These constraints can be overcome by intensive research and development in the field of agricultural mechanization.     

Management practice effects on phosphorus losses in runoff in corn production systems

Phosphorus losses in runoff from cropland can contribute to nonpoint-source pollution of surface waters. Management practices in corn (Zea mays L.) production systems may influence P losses. Field experiments with treatments including differing soil test P levels, tillage and manure application combinations, and manure and biosolids application histories were used to assess these management practice effects on P losses. Runoff from simulated rainfall (76 mm h(-1)) was collected from 0.83-m2 areas for 1 h after rainfall initiation and analyzed for dissolved reactive P (DRP), bioavailable P, total P (TP), and sediment. In no-till corn, both DRP concentration and load increased as Bray P1 soil test (STP) increased from 8 to 62 mg kg(-1). A 5-yr history of manure or biosolids application greatly increased STP and DRP concentrations in runoff. The 5-yr manure treatment had higher DRP concentration but lower DRP load than the 5-yr biosolids treatment, probably due to residue accumulation and lower runoff in the manure treatment. Studies of tillage and manure application effects on P losses showed that tillage to incorporate manure generally lowered runoff DRP concentration but increased TP concentration and loads due to increased sediment loss. Management practices have a major influence on P losses in runoff in corn production systems that may overshadow the effects of STP alone. Results from this work, showing that some practices may have opposite effects on DRP vs. TP losses, emphasize the need to design management recommendations to minimize losses of those P forms with the greatest pollution potential.     

Investigation of the inorganic and organic phosphorus forms in animal manure

The most viable way to beneficially use animal manure on most farms is land application. Over the past few decades, repeated manure application has shown adverse effects on environmental quality due to phosphorus (P) runoff with rainwater, leading to eutrophication of aquatic ecosystems. Improved understanding of manure P chemistry may reduce this risk. In this research, 42 manure samples from seven animal species (beef and dairy cattle, swine, chicken, turkey, dairy goat, horse, and sheep) were sequentially fractionated with water, NaHCO?, NaOH, and HCl. Inorganic (P(i)), organic (P(o)), enzymatic hydrolyzable (P(e); monoester-, DNA-, and phytate-like P), and nonhydrolyzable P were measured in each fraction. Total dry ash P (P(t)) was measured in all manures. Total fractionated P (P(ft)) and total P(i) (P(it)) showed a strong linear relationship with P(t). However, the ratios between P(ft)/P(t) and P(it)/P(t) varied from 59 to 117% and from 28 to 96%, respectively. Water and NaHCO? extracted most of the P(i) in manure from ruminant+horse, whereas in nonruminant species a large fraction of manure P was extracted in the HCl fraction. Manure P(e) summed over all fractions (P(et)) accounted for 41 to 69% of total P(0) and 4 to 29% of P(t). The hydrolyzable pool in the majority of the manures was dominated by phytate- and DNA-like P in water, monoester- and DNA-like P in NaHCO?, and monoester- and phytate-like P in NaOH and HCl fractions. In conclusion, if one assumes that the P(et) and P(it) from the fractionation can become bioavailable, then from 34 to 100% of P(t) in animal manure would be bioavailable. This suggests the need for frequent monitoring of manure P for better manure management practices.