Manure Management Systems Research Articles

Optimal Housing and Manure Management Strategies to Favor Productive and Environment-Friendly Dairy Farms in Québec, Canada: Part I. Representative Farm Simulations

Abstract. Tie-stall housing (93%) and solid manure management (44%) are used on many dairy farms in the province of Québec, Canada. However, this could change in the near future because the rise in average herd size and the popularity of milking robots are such that the industry expects an increase in free-stall dairies managing manure with liquid systems. This shift could affect the carbon (C), nitrogen (N), and phosphorus (P) footprints of Québec’s dairy production. In this context, whole-farm modeling (N-CyCLES), considering all the production cycle, provides a tool for evaluating the economics and environmental impacts of standard housing and manure management systems (Part I) in combination with different mitigation approaches (Part II). Two representative dairy farms in southwestern Québec (SWQ; 45.3° N, 73.2° W) and eastern Québec (EQ; 48.45° N, 68.1° W) were simulated considering four scenarios involving combinations of tie-stall or free-stall housing and solid or liquid manure management. Maximum farm net income (FNI) was $0.33 and $0.18 kg-1 of fat- and protein-corrected milk (FPCM) for the SWQ and EQ farms, respectively, with N and P footprints of 12.22 to 16.99 g N kg-1 and 0.52 to 0.79 g P kg-1 of FPCM in SWQ, and 11.48 to 15.39 g N kg-1 and 1.41 to 1.88 g P kg-1 of FPCM in EQ. Greenhouse gas (GHG) emissions reached 1.78 to 1.87 kg CO2e kg-1 and 1.67 to 1.71 kg CO2e kg-1 of FPCM in SWQ and EQ, respectively. The SWQ farm was associated with greater production of cash crops but also greater imports of fertilizers and purchased feeds, which negatively affected the N footprint and GHG emissions. Housing and manure management types did not influence FNI. Free-stall dairies were associated with greater N surpluses. Nevertheless, they emitted slightly less GHG than tie-stall dairies. Dairy farms under liquid manure management imported less fertilizers and produced less GHG despite greater CH4 emissions. As a result, the current transition toward free-stall barns and liquid manure systems in Québec seems advantageous from an environmental standpoint without compromising economic profitability. Keywords: Climate change, Dairy cow, Farm net income, Free stall, Greenhouse gas emission, Manure handling, Mitigation, Nutrient footprint, Tie stall, Whole-farm model.

Life-cycle Analysis of Advanced Manure Management Systems for a Wisconsin Confined Animal Feeding Operation (CAFO)

Abstract. Manure management is becoming an increasing burden for large dairy farms in Wisconsin and across the United States due to land application limitations for nutrients and hauling costs. One solution is to install advanced manure management systems, which remove large portions of water from the manure and treat it to a level sufficient for surface water discharge, livestock consumption, or irrigation. These systems can be divided into a pretreatment stage, which consists of solids removal, and a treatment stage, which generally consists of membranes. Not only does this approach reduce the quantity of material that is land applied, it can separate the nutrients into individual manure streams that can be more easily managed. However, there is still limited understanding regarding the costs and operation and maintenance requirements of these systems. To this end, a life-cycle analysis was completed for five commercially available advanced manure management systems based on how they would treat manure from a 3,500-cow dairy farm in Wisconsin, which was concerned only with the drawbacks of hauling and not application limitations. The evaluation included both an economic and non-economic analysis. The economic analysis consisted of a 20-year total present worth life-cycle cost analysis. The non-economic analysis consisted of a comparison of a set of non-economic factors that matched the management goals and strategies identified by the participating farm. Overall, all five systems evaluated addressed nutrient limitations and hauling costs. No treatment system had a payback less than 20 years at a hauling cost of $0.0040 L-1 ($0.015 gal-1). However, two systems had a payback period less than 20 years for a hauling cost of $0.0053 L-1 ($0.02 gal-1). Furthermore, if capital costs were ignored, the cost of recovered water was comparable to hauling costs for four of the alternatives. Still, there was high uncertainty in the estimated costs due to the low number of current installations of these systems on CAFOs. There was also a wide range of responses to the non-economic evaluation metrics, especially regarding performance, nutrient management techniques, chemical usage, and estimated regular operation and maintenance, which was again, likely due to the limited number of farm installations. Future work will verify actual costs and performance of these systems once implemented. Keywords: Advanced Manure Management, CAFOs, Dairy, Life-cycle analysis.

A new torrefaction system employing spontaneous self-heating of livestock manure under elevated pressure

This report describes a new oxidative torrefaction method employing spontaneous self-heating of feedstock as a means of overcoming practical difficulties in converting livestock manure to biochar. We examined the initiating temperature required to induce self-heating of wet dairy cattle manure under 1.0 MPa pressure and conducted elemental and calorific analyses of the solid products prepared at 200, 250, and 300 °C. Self-heating was initiated with oxidation below 100 °C, and the lower limit of the initiation temperature was between 85 and 90 °C. Comparing processes performed at 0.1 and 1.0 MPa, the higher pressure promoted self-heating by both preventing heat loss due to moisture evaporation occurring at approximately 100 °C and supplying oxygen to the high-moisture feedstock. In addition, as drying occurred at 160–170 °C during the process, the system did not require pre- or post-drying. Although the heating values of the solid products decreased due to high ash content, the elemental composition of the products was altered to that of peat-like (200 °C) and lignite-like (250 and 300 °C) materials. Cessation of self-heating of the manure is recommended at approximately 250 °C to avoid severe decomposition at higher temperatures. Overall, these results demonstrated the utility of the proposed method for converting wet manure into dried biochar through self-heating as well as potential applications in manure management systems.

Global Warming and Acidification Potential Assessment of a Collective Manure Management System for Bioenergy Production and Nitrogen Removal in Northern Italy

Collective manure processing facilities to reduce nutrient loads and produce renewable energy are often proposed as feasible solutions in intensive livestock production areas. However, the transferring of effluents from farms to the treatment plant and back to farms, as well as the treatment operations themselves, must be carefully evaluated to assure the environmental sustainability of the solution. This study evaluated the global warming potential (GWP) and acidification potential (AP) of a collective treatment plant for bioenergy production and nitrogen removal as an alternative strategy to conventional on-farm manure management systems. Two manure management scenarios were compared: manure management on individual farms and management by a collective treatment plant. Data were collected at a collective processing plant and at the individual farms of the consortium to estimate emissions of CO2, CH4, N2O, NOx, NH3 and SO2. The plant receives manure from 21 livestock production units, treating 660 tonnes day−1 of manure. The GWP and AP indicators were calculated to evaluate the potential impact of the two management solutions. The collective solution reduced both GWP (−52%) and AP (−43%) compared to manure management separately by each farm. Further improvement might be obtained in both indicators by introducing mitigation techniques in farm manure storage and manure application to soil.

Monitoring of greenhouse gas emissions from farm-scale anaerobic piggery waste-water digesters

AbstractPig manure management systems in Taiwan differ from the model representing the Asian region developed by the Intergovernmental Panel on Climate Change (IPCC). The current study was undertaken to update greenhouse gas (GHG) emission factors of anaerobically treated piggery waste water by operating the conventional three-step piggery waste-water treatment system from selected pig farms located in northern, central and southern Taiwan. Biogas mass flow meters were installed to the outlet of anaerobic basins prior to the biogas pressure stabilizers for direct and reliable biogas measurement. The analytic results showed that average GHG emissions were 0.088, 0.128 and 0.066 m3/head/day in the northern, central and southern pig farms, respectively. Thus, the average emission levels of methane and nitrous oxide were 14.38 and 0.055 kg/head/year, respectively, from anaerobic digestion of piggery waste water for the three pig farms. The average removal efficiency of chemical oxygen demand, biochemical oxygen demand and suspended solids by anaerobic digestion process from the three pig farms was about 77, 93 and 70%, respectively.

Phosphorus Characterisation of Sludge and Crust Produced by Stabilisation Ponds in a Dairy Manure Management System

In dairy farming, recirculation and continuous use of nutrients are necessary for sustainable nutrient management in both the short- and long-term. When managed effectively, nutrient recycling can improve soil fertility. On the other hand, if applied nutrients are in excess of the soil’s nutrient holding capacity, nutrients can enter surface and ground water bodies resulting in eutrophication. Phosphorus (P) characterisation in manure, pond sludge and crust, in terms of plant availability, is the first step to sustainably manage nutrients within dairy farms. In this study, pond sludge and crust were characterised for P using a sequential fractionation method. Pond sludge and crust contained significant amounts of labile P. Water extractable P (H2O-P) in primary anaerobic pond and secondary facultative pond sludges was found to be about 8 to 13 times higher than the amount found in the surface soil (0–10 cm) of a grazing paddock. Similarly, sodium bicarbonate extractable P (NaHCO3-P) in the two types of sludges was found to be about 6 times higher than in the soil. The relatively higher labile P (H2O-P and NaHCO3-P) in sludge compared to soil indicates that the sludge can be utilised as a P fertilizer on grazing pasture. In contrast, lower H2O-P compared to that of raw manure indicates that the use of sludge and crust instead of raw manure can reduce the possibility of P loss by surface runoff and leaching. Hence, it is preferable to use pond sludge and crust as fertiliser instead of raw manure.

An Eco-Friendly System for the Production of Value-Added Materials from Dairy Manure

A concept is outlined for the production of materials/commodities from a polluting waste. A preliminary evaluation is presented for a proposed integrated dairy farm manure management system consisting of a two-stage anaerobic digester coupled with a polyhydroxyalkanoate reactor, algae cultivation system (ACS) and a biomass treatment system, such as fast-pyrolysis or hydrothermal liquefaction, to sequester carbon, nitrogen and phosphorus into value-added products (e.g., bioplastics, biogas, fertilizer, soil amendment and livestock bedding) rather than releasing them into the environment. Mass flows through the system are presented for a 10,000-cow dairy. The integrated manure treatment system can reduce the amount of nitrogen and phosphorus released from the manure by 50.9% and 38.1%, respectively. Without an ACS, the reduction drops to 19% and 27%, respectively. Greenhouse gas emissions can potentially be reduced by 44,200 MT CO2e/year over the referenced open lot dairy.

Greenhouse Gas Emission Intensities for the Livestock Sector in Indonesia, Based on the National Specific Data

The aims of this study were to calculate greenhouse gas (GHG) emissions and to identify the trends of GHG emission intensity, based on meat production from the livestock sector in Indonesia, which had not been done before. The total emissions from the livestock sector from 2000 to 2015 in Indonesia were calculated using the 2006 Intergovernmental Panel on Climate Change Guideline (2006 IPCC GL) using Tier 1 and Tier 2, with its default values and some of the country specific data that were found in the grey literature. During 2000 to 2015, the change from the Tier 1 to Tier 2 methods resulted in an approximately 7.39% emission decrease from enteric fermentation and a 4.24% increase from manure management, which resulted in a 4.98% decrease in the total emissions. The shared emission from manure management increased by about 9% and 6% using Tier 1 and Tier 2, respectively. In contrast with the total emissions, the overall emission intensity in Indonesia decreased (up to 60.77% for swine), showing that the livestock productivity in Indonesia has become more efficient. In order to meet the meat demand with less GHG emissions, chicken farming is one option to be developed. The increased emission and share from manure management indicated that manure management system needs to be of concern, especially for beef cattle and swine.

Trade-offs between Manure Management with and without Biogas Production

Introduction: In rural developing countries with a traditional manure management, animal manure is a value-added agricultural commodity being utilized as a source of fuel and plant nutrients. The sustainable environmental management of this resource has to consider the whole upstream and downstream activities of current management systems. Methods & Materials: In line with this requirement, this study has integrated the Intergovernmental Panel on Climate Change (IPCC) method on manure managements into the life-cycle assessment of two different manure management systems: the traditional system without biogas production and the alternative system with biogas production. Special attention is given to compare the GHG emissions as well as Nitrogen (N), Phosphorous (P), and Potassium (K) Fertilizing Nutrients (NPK) from the two systems. Results: The great advantage of manure conversion to biogas is mainly due to the avoided wood (18 kg/animal.yr), crop-residues (12 kg/ animal.yr) and dung (8 kg/ animal.yr) used as cooking fuels in the region. If methane leakage is over 38% then this will offset the GHG emission reduction of manure-to-biogas system.

Ammonia and greenhouse gas emissions from slatted dairy barn floors cleaned by robotic scrapers

The design of animal housing and manure management systems are key factors in livestock farming. Frequent removal methods, in fact, allow for the reduction of gasses produced from fermentations of the organic matter contained in manure, that affect animal welfare and farmer health and are emitted from animal housings into the atmosphere as a consequence of ventilation. The present study aims to evaluate the performance of a Robotic Scraper (RS) operating on the floors in a full-scale, operative free-stall dairy barn. The research is focused on the evaluation of gaseous emissions from the two types of floors (concrete and rubber mat coated), and with and without RS operation. The floors with rubber coating demonstrated higher emission rates of ammonia (NH<sub>3</sub>), carbon dioxide (CO<sub>2</sub>), nitrous oxide (N<sub>2</sub>O), and methane (CH<sub>4</sub>) compared to the uncovered concrete floors, both before and after RS operations. The operation of RS, furthermore, determined significant reduction of greenhouse gasses (GHG) but did not have relevant effect in terms of NH<sub>3</sub> emission, which reduced only of 1.4% from concrete floors, but increase of 12.7% from rubber coated floors.

Occurrence and transformation of veterinary antibiotics and antibiotic resistance genes in dairy manure treated by advanced anaerobic digestion and conventional treatment methods.

Manure treatment technologies are rapidly developing to minimize eutrophication of surrounding environments and potentially decrease the introduction of antibiotics and antibiotic resistant genes (ARGs) into the environment. While laboratory and pilot-scale manure treatment systems boast promising results, antibiotic and ARG removals in full-scale systems receiving continuous manure input have not been evaluated. The effect of treatment on ARGs is similarly lacking. This study examines the occurrence and transformation of sulfonamides, tetracyclines, tetracycline degradation products, and related ARGs throughout a full-scale advanced anaerobic digester (AAD) receiving continuous manure and antibiotic input. Manure samples were collected throughout the AAD system to evaluate baseline antibiotic and ARG input (raw manure), the effect of hygenization (post-pasteurized manure) and anaerobic digestion (post-digestion manure) on antibiotic and ARG levels. Antibiotics were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the ARGs tet(O), tet(W), sul1 and sul2 were analyzed by quantitative polymerase chain reaction (Q-PCR). Significant reductions in the concentrations of chlortetracycline, oxytetracycline, tetracycline and their degradation products were observed in manure liquids following treatment (p < 0.001), concomitant to significant increases in manure solids (p < 0.001). These results suggest sorption is the major removal route for tetracyclines during AAD. Significant decreases in the epimer-to-total residue ratios for chlortetracycline and tetracycline in manure solids further indicate degradation is desorption-limited. Moreover, sul1 and sul2 copies decreased significantly (p < 0.001) following AAD in the absence of sulfonamide antibiotics, while tetracyclines-resistant genes remained unchanged. A cross-sectional study of dairy farms utilizing natural aeration and liquid-solid separation treatments was additionally performed to compare levels of antibiotics and ARGs found in AAD with the levels in common manure management systems. The concentration of antibiotics in raw manure varied greatly between farms while minimal differences in ARGs were observed. However, significant (p < 0.01) differences in the levels of antibiotics and ARGs (except tet(W)) were observed in the effluents from the three different manure management systems.

Sources of nitrous oxide and other climate relevant gases on surface area in a dairy free stall barn with solid floor and outside slurry storage

Livestock production systems in agriculture are one of the major emitters of greenhouse gases. So far, the focus of research in the dairy farm sector was primarily on ruminal methane (CH4) emissions. Emissions of nitrous oxide (N2O) usually arise from solid manure or in deep litter free stall barns. Release of N2O occurs as a result of interactions between organic material, nitrogen and moisture. Data of N2O emissions from modern dairy barns and liquid manure management systems are rare. Thus, the goal of this research was to determine the main sources of trace gas emissions at the dairy farm level, including N2O. Areas such as the scraped surface area where dry and wet conditions alternate are interesting. Possible sources of trace gases within and outside the barn were localised by measuring trace gas concentration rates from different dairy farm areas (e.g., areas covered with urine and excrement or slurry storage system) via the closed chamber technique. The results indicate typical emission ratios of carbon dioxide (CO2), CH4 and N2O in the various areas to generate comparable equivalent values. Calculated on the basis of nitrogen excretion from dairy cows, total emissions of N2O were much lower from barns than typically measured in fields. However, there were also areas within the barn with individual events and unexpected release factors of N2O concentrations such as urine patches, polluted areas and cubicles. Emission factors of N2O ranged from 1.1 to 5.0 mg m−2 d−1, respectively, for cleaned areas and urine patches. By considering the release factors of these areas and their proportion of the entire barn, total emission rates of 371 CO2-eq. LU−1 a−1, 36 CO2-eq. LU−1 a−1, and 1.7 kg CO2-eq. LU−1 a−1 for CO2, CH4 and N2O, respectively, were measured for the whole barn surface area. The CH4 emissions from surface area were stronger climate relevant comparing to N2O emissions, but compared to CH4 emissions from slurry storage or ruminal fermentation (not measured) even insignificant.

Different approaches to assess the environmental performance of a cow manure biogas plant

In intensive livestock production areas, farmers must apply manure management systems to comply with governmental regulations. Biogas plants, as a source of renewable energy, have the potential to reduce environmental impacts comparing with other manure management practices. Nevertheless, manure processing at biogas plants also incurs in non-desired gas emissions that should be considered. At present, available emission calculation methods cover partially emissions produced at a biogas plant, with the subsequent difficulty in the preparation of life cycle inventories. The objective of this study is to characterise gaseous emissions: ammonia (NH3-N), methane (CH4), nitrous oxide (N2Oindirect, and N2Odirect) and hydrogen sulphide (H2S) from the anaerobic co-digestion of cow manure by using different approaches for preparing gaseous emission inventories, and to compare the different methodologies used. The chosen scenario for the study is a biogas plant located next to a dairy farm in the North of Catalonia, Spain. Emissions were calculated by two methods: field measurements and estimation, following international guidelines. International Panel on Climate Change (IPCC) guidelines were adapted to estimate emissions for the specific situation according to Tier 1, Tier 2 and Tier 3 approaches. Total air emissions at the biogas plant were calculated from the emissions produced at the three main manure storage facilities on the plant: influent storage, liquid fraction storage, and the solid fraction storage of the digestate. Results showed that most of the emissions were produced in the liquid fraction storage. Comparing measured emissions with estimated emissions, NH3, CH4, N2Oindirect and H2S total emission results were in the same order of magnitude for both methodologies, while, N2Odirect total measured emissions were one order of magnitude higher than the estimates. A Monte Carlo analysis was carried out to examine the uncertainties of emissions determined from experimental data, providing probability distribution functions. Four emission inventories were developed with the different methodologies used. Estimation methods proved to be a useful tool to determine emissions when field sampling is not possible. Nevertheless, it was not possible to establish which methodology is more reliable. Therefore, more measurements at different biogas plants should be evaluated to validate the methodologies more precisely.

How do farm models compare when estimating greenhouse gas emissions from dairy cattle production?

The European Union Effort Sharing Regulation (ESR) will require a 30% reduction in greenhouse gas (GHG) emissions by 2030 compared with 2005 from the sectors not included in the European Emissions Trading Scheme, including agriculture. This will require the estimation of current and future emissions from agriculture, including dairy cattle production systems. Using a farm-scale model as part of a Tier 3 method for farm to national scales provides a more holistic and informative approach than IPCC (2006) Tier 2 but requires independent quality control. Comparing the results of using models to simulate a range of scenarios that explore an appropriate range of biophysical and management situations can support this process by providing a framework for placing model results in context. To assess the variation between models and the process of understanding differences, estimates of GHG emissions from four farm-scale models (DairyWise, FarmAC, HolosNor and SFARMMOD) were calculated for eight dairy farming scenarios within a factorial design consisting of two climates (cool/dry and warm/wet)×two soil types (sandy and clayey)×two feeding systems (grass only and grass/maize). The milk yield per cow, follower:cow ratio, manure management system, nitrogen (N) fertilisation and land area were standardised for all scenarios in order to associate the differences in the results with the model structure and function. Potential yield and application of available N in fertiliser and manure were specified separately for grass and maize. Significant differences between models were found in GHG emissions at the farm-scale and for most contributory sources, although there was no difference in the ranking of source magnitudes. The farm-scale GHG emissions, averaged over the four models, was 10.6 t carbon dioxide equivalents (CO2e)/ha per year, with a range of 1.9 t CO2e/ha per year. Even though key production characteristics were specified in the scenarios, there were still significant differences between models in the annual milk production per ha and the amounts of N fertiliser and concentrate feed imported. This was because the models differed in their description of biophysical responses and feedback mechanisms, and in the extent to which management functions were internalised. We conclude that comparing the results of different farm-scale models when applied to a range of scenarios would build confidence in their use in achieving ESR targets, justifying further investment in the development of a wider range of scenarios and software tools.

Performance Quantification of Manure Management Systems at 11 Northeastern U.S. Dairy Farms

Abstract. The performance of manure management systems, on a component-by-component basis, at 11 Northeastern U.S. dairy farm concentrated animal feeding operations (CAFO) was quantified by semi-continuous monitoring for 15 months. Each collaborating farm (CF) had one or more of the following: solid-liquid separation (SLS), separated solids(SS) treatment by lime, rotary drum processing and windrow composting, anaerobic treatment by anaerobic digestion (AD), lagoons, and long-term storage(s). Operational and performance metrics included: temperature, pH, total solids (TS), volatile solids (VS), loading rates, and biogas production. Generally, most CFs had functional and well-operating systems based on expected and optimal operating conditions and sample constituent changes, although, sampling and monitoring limitations restricted complete performance assessments. Despite the limitations, differences in treatment effectiveness were noted, which were often related to influent conditions. Higher SLS solids capture efficiencies (typ. &amp;gt; 40%), and biogas production rates (= 3.8 m3 d-1 lactating cow equivalents (LCE)-1), were associated with more concentrated manure slurry influents [TS &amp;gt; 0.050 g g-1 wet basis (w.b.)]. Anaerobic digester configuration and the use of co-substrates also influenced anaerobic treatments. Generally, intensively managed ADs outperformed passively managed lagoons, and co-digestion enhanced biogas production (= 4.3 m3 d-1 LCE-1) and VS reductions (up to 48% w.b.), though co-digestion sometimes hampered process stability. The effectiveness of SS processing was also treatment dependent, with well-managed windrows yielding the greatest increases in TS concentrations (up to 0.600 g g-1 w.b.). Long-term storage of manure slurry had modest, non-significant, impacts on TS and VS concentrations, and pH. This work illustrated a range of manure management systems used on NE dairy farm CAFOs, parameterized their treatment of manure slurries and SS, and established a baseline for additional studies aimed at the capacity of these systems to mitigate emerging contaminant like antibiotic residues. Keywords: Anaerobic digestion, Antimicrobial resistance, Biogas, Compost, Lime treatment, Long-term storage, Solid-liquid separation.

Assessment of greenhouse gas emissions from the pig production in Lam Dong

Applying the methodology of the Intergovernmental Panel on Climate Change (IPCC) in calculating the greenhouse gas emission from pig farming operations at Lam Dong province in 2015, calculated results show that the application of swine manure management solutions can significantly reduce emissions of greenhouse gases into the environment. Using of energy in pig farming operations around 0.0007 tCO2 emissions/ head/ month, the digestion of pig feed create a greenhouse gas emission at around 152.96 tCO2/month with emission factor of 0.0029 tCO2/head / month. Greenhouse gases emitted from the current manure management system (manure are treated by various forms and the rest will directly disposed into the environment) into the atmosphere is around 400.08tCO2/month, respectively a pig emitted about 0.0076 tCO2/head/month. The total emission factor during pig production under the scenarios: (1) manure are directly discharged into the environment, (2) manure are managed by current management system, (3) manure are managed by current management systems with the gas generated from biogas recovery is converted into electrical energy and (4) manure are managed by Biogas recovery system, respectively 0.0593; 0.0112; 0.0101; 0.0077 tCO2/ head/month.

Environmental impacts and resource use of milk production on the North China Plain, based on life cycle assessment

Life cycle assessment methodology was used to quantify the environmental impacts and resource use of milk production on the North China Plain, the largest milk production area in China. Variation in environmental burden caused by cow productivity was evaluated, as well as scenario analysis of the effects of improvement practices. The results indicated that the average environmental impact potential and resource use for producing 1kg of fat and protein corrected milk was 1.34kgCO2eq., 9.27gPO43−eq., 19.5gSO2eq., 4.91MJ, 1.83m2 and 266L for global warming potential (GWP), eutrophication potential (EP), acidification potential (AP), non-renewable energy use (NREU), land use (LU) and blue water use (BWU; i.e. water withdrawal), respectively. Feed production was a significant determinant of GWP, NREU, LU and BWU, while AP and EP were mainly affected by manure management. Scenario analysis showed that reducing use of concentrates and substituting with alfalfa hay decreased GWP, EP, AP, NREU and LU (by 1.0%–5.5%), but caused a significant increase of BWU (by 17.2%). Using imported soybean instead of locally-grown soybean decreased LU by 2.6%, but significantly increased GWP and NREU by 20% and 6.9%, respectively. There was no single perfect manure management system, with variable effects from different management practices. The environmental burden shifting observed in this study illustrates the importance of assessing a wide range of impact categories instead of single or limited indicators for formulating environmental policies, and the necessity of combining multiple measures to decrease the environmental burden. For the North China Plain, improving milking cow productivity and herd structure (i.e. increased proportion of milking cows), combining various manure management systems, and encouraging dairy farmers to return manure to nearby crop lands are promising measures to decrease multiple environmental impacts.

Selection of pig manure management strategies: Case study of Polish farms

The goal of the study is to propose a pig manure management system that is useful for the owners of 30,000 ha of arable lands and a group of five Polish pig farms that produce approximately 240,000 m3 y−1 of pig manure. The BATNEEC options method was used to evaluate three selected systems of pig manure management: storage, utilisation for fertilization, and processing by filtration using the AMAK method for fertilizer production. These options were evaluated on the basis of specific formulated criteria. The processing by the AMAK method was rated very highly (89% maximum). However, very low scores were given for fertilization with pig manure and its storage (39% and 22% maximum, respectively). The system proposed for pig manure management was as follows: elimination of manure storage in lagoons, application of roughly half the pig manure as fertilizer, processing of the other half by the AMAK method on each farm, and the use of a separated solid phase to produce mineral-organic fertilizers in one central unit.

Farm-scale greenhouse gas balances, hotspots and uncertainties in smallholder crop-livestock systems in Central Kenya

Abstract Climate-smart approaches have gained momentum in tropical, agricultural development. However, to date, few studies have examined whole-farm greenhouse gas (GHG) balances in smallholder crop-livestock systems. This study aimed to quantify GHG balances at farm-scale, identify GHG hotspots and assess mitigation options in coffee-dairy farms undergoing agricultural intensification in Central Kenya. In recent decades, decreasing farm size has forced the shift from extensive practices to zero-grazing systems and higher nitrogen (N) inputs. We hypothesised that different farm strategies and intensification levels determine the farm’s GHG balance. A farm typology was constructed through principal component analysis (PCA) and hierarchical clustering from 125 farms surveyed. Four farm types were identified ranging relatively from small to large farms, low to high livestock intensities, and low to high N input rates. Whole-farm GHG balances were estimated using an adapted version of the Cool Farm Tool (CFT). Farms were found to be net sources of GHG, averaging from 4.5 t CO 2 eq ha −1 yr −1 in less intensive farms to 12.5 t CO 2 eq ha −1 yr −1 in high intensive farms. Within the farm GHG hotspots identified, methane (CH 4 ) from enteric fermentation processes accounted for 26–39% of total farm GHG emissions; nitrous oxide (N 2 O) and CH 4 from manure management systems (MMS) for 26–38%; soil background and fertilizer induced N 2 O emissions for 24–29%; off-farm production of feeds and agrochemicals for 10–22%; and crop residue management (CRM) for the remaining 1–3%. Within the mitigation practices assessed, zero-grazing stalls already lowered the livestock maintenance energy requirements, reducing enteric fermentation emissions. Stall-feeding, however, brings the necessity-opportunity to manage the manure and our results showed that MMS can be a determining factor in the GHG balance. Increasing the frequency of manure collection from stalls in favour of solid storage systems can reduce N 2 O emissions by up to 75%. Furthermore, dry manure storage reduced the CH 4 emissions of liquid slurry systems by more than 70%. Further benefits in terms of carbon (C) sequestration were identified along farm types from manure and crop residues applications in soils (with averages of −1.3 to −2.3 t CO 2 eq ha −1 yr −1 ) and biomass growth in agroforestry systems (−1.2 to −2 t CO 2 eq ha −1 yr −1 ). Together, soils and woody biomass offset 25–36% of farm emissions. We conclude that reduced farm size and increased livestock density lead to higher emissions per unit area, though this increase is smoothed by larger negative fluxes in soils (by higher C inputs) and woody biomass (by higher tree densities) until a steady state is reached. Average yield-scaled emissions, or product carbon footprints (CFs), resulted in 1.08 kg CO 2 eq kg coffee berry −1 , 0.64 kg CO 2 eq kg maize −1 and 1.05 kg CO 2 eq kg milk −1 on average. CFs did not always differ between farm types and intensification levels, meaning that increases in productivity were not higher than increases in GHG fluxes from intensification. This may be due to: 1) increases in productivity are the result of more processes other than N inputs; and/or 2) emissions from N inputs are overestimated by EFs and GHG calculators. Smallholders may benefit in the near future from climate initiatives and further field characterisation, models calibration and monitoring are required to overcome critical levels of uncertainty and provide more accurate estimations of GHG balances at farm-scale.

Mitigating Greenhouse Gas and Ammonia Emissions from Swine Manure Management: A System Analysis.

Gaseous emissions from animal manure are considerable contributor to global ammonia (NH3) and agriculture greenhouse gas (GHG) emissions. Given the demand to promote mitigation of GHGs while fostering sustainable development of the Paris Agreement, an improvement of management systems is urgently needed to help mitigate climate change and to improve atmospheric air quality. This study presents a meta-analysis and an integrated assessment of gaseous emissions and mitigation potentials for NH3, methane (CH4), and nitrous oxide (N2O) (direct and indirect) losses from four typical swine manure management systems (MMSs). The resultant emission factors and mitigation efficiencies allow GHG and NH3 emissions to be estimated, as well as mitigation potentials for different stages of swine operation. In particular, changing swine manure management from liquid systems to solid-liquid separation systems, coupled with mitigation measures, could simultaneously reduce GHG emissions by 65% and NH3 emissions by 78%. The resultant potential reduction in GHG emissions from China's pig production alone is greater than the entire GHG emissions from agricultural sector of France, Australia, or Germany, while the reduction in NH3 emissions is equivalent to 40% of the total NH3 emissions from the European Union. Thus, improved swine manure management could have a significant impact on global environment issues.