Manure Management Technologies Research Articles

Consequential versus attributional life cycle optimization of poultry manure management technologies in a food-energy-water-waste nexus

To model the environmental and economic tradeoffs of managing poultry manure wastes in a food-energy-water-waste nexus, this work builds a framework to conduct a combined life cycle and techno-economic optimization and a spatial analysis of poultry manure management technologies. To align with the United Nations Sustainable Development Goals 6: Clean Water and Sanitation and 13: Climate Action by mitigating the massive water and climate impacts induced by the common practice of fertilizer crops using direct land application of poultry manure, the framework minimizes freshwater eutrophication (FE) impact and climate change impact (GWP). To account for the circular economy, the net present value (NPV) is maximized to measure the economic feasibility of implementing alternative management pathways. A multi-objective mixed-integer non-linear programming framework accounts for the selection of direct land application, and waste to energy technologies, spatial variation in manure supply, facility sizing, and the products’ consumption and end-of-life. This optimization framework is evaluated for a case study in New York state. Under an attributional life cycle optimization, anaerobic digestion minimizes FE with an impact of 0.002 kg P-eq/ton manure, while using a consequential life cycle optimization, hydrothermal carbonization minimizes FE with an impact of −0.96 kg P-eq/ton manure. For both life cycle methodologies, pyrolysis with land application of biochar minimizes GWP. At the attributional life cycle assessment tradeoff point for GWP and NPV, minimum carbon credits of US$33/ton CO2-eq are necessary for a pyrolysis plant to have a positive NPV, implying that harnessing economies of scale or robust carbon accounting is necessary for the widespread adoption of pyrolysis as a poultry manure management technology.

A Review on the Anaerobic Co-Digestion of Livestock Manures in the Context of Sustainable Waste Management

As the worldwide demand for meat per person is continuously increasing, there is a corresponding rise in the number of livestock animals, leading to an increase in livestock manure. Selecting appropriate treatment technologies for livestock manures is still a complex task and considerable debates over this issue persist. To develop a more comprehensive understanding of the manure treatment framework, this review was undertaken to assess the most utilized manure management technologies and underscore their respective challenges. Anaerobic digestion has become a commercial reality for treating livestock manures. However, the mono-digestion of single substrates comes with certain drawbacks associated with manure characteristics. Anaerobic co-digestion, involving the utilization of multiple feedstocks, holds the potential to overcome these limitations. Extensive research and development have underscored numerous intrinsic benefits of co-digestion. These include improved digestibility resulting from the synergistic effects of co-substrates and enhanced process stability. This review underscores the limitations associated with the mono-digestion of livestock manures and critically evaluates the advantages of their co-digestion with carbon-rich substrates. Additionally, this review delves into key livestock manure management practices globally, emphasizing the significance of co-digesting livestock manures while addressing the progress and challenges in this field.

Composting post-anaerobic digestion for emerging contaminant biodegradation: Impacts of operating conditions.

Sustainable manure management technologies are needed, and combining anaerobic digestion (AD) for energy generation and aerobic composting (AC) to stabilize digestate and remove emerging contaminants (ECs), including veterinary pharmaceuticals and steroid hormones, is promising. This study identified post-AD, AC operating conditions that maximized degradation of study ECs, expected to be present in cattle manure digested using treated municipal wastewater as the water source. Study ECs included sulfamethoxazole (SMX), chlortetracycline (CTC), oxytetracycline (OTC), estrone (E1), and naproxen (NPX). Composting conditions were simulated in bench-scale reactors, with microorganisms from digestate produced in an AD system (25L scale), by varying temperatures, pH, and carbon source compositions (representing food waste/manure co-digestion with different residence times). Results indicate maximum SMX biodegradation occurred at 35°C, pH 7, and with high levels of easily degradable carbon (≥99%, 99%, and 98%), and maximum E1 biodegradation occurred at 35°C, and with low levels of easily degradable carbon (≥97% and 99%). Abiotic degradation was responsible for the nearly complete removal of tetracyclines under all conditions and for partial degradation of NPX (between 20% and 48%). Microorganisms originating from the AD system putatively capable of SMX and E1 biodegradation, or of contributing to biodegradation during the AC phase, were identified, including phylotypes previously shown to biodegrade SMX (Brevundimonas and Alcaligenes).

Representative Survey for Evaluating Housing and Manure Handling Technologies of the Hungarian Pig Sector.

In Hungary, there is a lack of information on the pig production technologies in place in the base year of 2005 and changes since then, as well as a lack of information on the number of pigs kept in different age and production categories, which makes it difficult to calculate ammonia emissions and reductions in the national inventories. Our research team conducted a representative survey of pig farms to assess housing and manure management technologies in the Hungarian pig sector in 2005 and 2015. Novel expert-based calculation methods were developed to convert farm data on pig populations into daily average numbers (DAN) of animals in different statistical categories and feeding phases. The survey resulted in a representative database of housing, manure handling, storage and manure application practices in Hungarian pig production. The data and methodology from the survey helped to develop an ammonia emission calculator and knowledge transfer tool (AGEM-S) for use by farmers.

Life cycle assessment of emissions in construction and operation phases of liquid swine manure management technologies

Life cycle assessment of emissions in construction and operation phases of liquid swine manure management technologies

Anaerobic Digestion and Alternative Manure Management Technologies for Methane Emissions Mitigation on Californian Dairies

California is the leading dairy state in the United States. The total sale of milk and its products represents about $6.3 billion annually out of the $50 billion generated from all agricultural production in the state. However, methane emissions from dairy manure and enteric fermentation represented nearly half of all annual methane emissions in California, with dairy manure accounting for 25%, and enteric fermentation for 20%. Methane emissions originating from manure are produced primarily from anaerobic settling basins and lagoons, which are the most common manure storage systems in the state. To achieve sustainability on dairy farms and to comply with state regulations for air and climate pollutants, dairy farms have implemented technologies such as anaerobic digestion and alternative manure management technologies. In addition, governmental incentive programs have been deployed to partially fund these technologies for eligible dairies in the state. The present article reviews the design and operations, effectiveness, and economics of the most common technologies employed in Californian dairies in reducing methane emissions. The technologies studied include anaerobic digesters, mechanical separators, compost-bedded pack barns, manure vacuuming followed by drying, and weeping walls. The current status and estimated effectiveness of government incentive programs are reviewed and recommendations for improvements presented. Finally, future trends and research needs for mitigating the emissions in Californian dairies are identified.

The role of biochar and zeolite in enhancing nitrogen and phosphorus recovery: A sustainable manure management technology

Swine manure is a potential source of plant-available ortho-phosphate (ortho-P) and ammonium (NH4+). However, transport and application issues restrict its widespread use in agriculture and cause water quality degradation. This study investigates the potential of biochar (BC) produced from corn stover (control-BC) and FeSO4 pretreated corn stover (Fe-BC) and zeolite to recover ortho-P and NH4+ from liquid swine manure. Chemisorption increased ortho-P sorption from manure onto Fe-BC (29,831 mg kg−1) relative to control-BC (19,000 mg kg−1). During Mehlich III (M−III) desorption study, manure-treated Fe-BC and control-BC released 34% and 80% of adsorbed ortho-P, respectively. Increasing the BC loading rate from 5 g/L to 25 g/L in manure significantly dropped the M−III P desorption (<10%) for the Fe-BC but not for the control-BC. Sorption of manure NH4+ on Fe-BC, control-BC, and zeolite occurred by I) specific adsorption on surfaces and within pores, II) co-adsorption of NH4+ with manure colloids, and III) precipitation as N-mineral (struvite). The NH3 volatilization and KCl desorption studies revealed that NH4+ sorption/desorption from manure to BC cannot be explained by simple ion exchange or volatilization loss. The BC-zeolite combination increased the NH4+ recovery from manure (28–38%) relative to BC’s without zeolite addition. SEM-EDS and XRD analyses revealed the association of P with both Mg and Fe and the presence of struvite (NH4MgPO4·6H2O) in batch and centrifuge studies. Our results suggest that low-cost BC and zeolite can recover ortho-P and NH4+ from liquid swine manure, which may facilitate its easy transport and widespread application in agriculture.

On-farm circular technologies for enhanced sustainability: The case of Uruguay

An increasing global population is putting stress on the food system. On-farm technologies to close resource loops will play a role in increasing food production without stressing natural resources. What are these applied on-farm circular technologies and what impact do they have on the food system? This paper develops a framework for defining the potential of on-farm circular technologies for benefits across multiple spatial scales. It then applies the framework to Uruguay to examine what economic and environmental benefits on-farm circular technologies, namely biomass for nutrient cycling (manure management) and on-farm water cycling, can have at multiple spatial scales – on-farm, regionally and nationally. Using data from a government program in Uruguay's most important watershed, the work shows that investments in on-farm manure management technologies yield economic and sustainability benefits that are unequally distributed across scales (Figure 1). It demonstrates that famers only receive a small percentage (16% on average) of the total benefits yielded by manure management and on-farm water cycling technologies, while most benefits (84% on average) occur at regional level. The analysis by technology demonstrates that the benefits of technologies also depend on how they are combined. For example, installing only a waste management pool on-farm increases the GHG emissions, while installing a waste management pool combined with a separator decreases the GHG emissions and magnifies the benefits of reduced water pollution. These findings raise questions regarding whether these technologies should be subsidized since most benefits occur beyond the farm level to the benefit of society. This has implications for how governments and private actors co-finance on-farm technologies to make farming practices more circular and sustainable.

Effect of natural and regulatory conditions on the environmental impacts of pig slurry acidification across different regions in Europe: A life cycle assessment

Animal manure handling is an essential but challenging part of Europe's intensive agriculture. To safeguard the environment and facilitate sustainable livestock production, lower-impact manure management technologies need to be identified, evaluated and implemented. Slurry acidification has been developed to address some of the environmental challenges faced by pig farmers, such as methane and ammonia emissions, that contribute to environmental impacts such as climate change, terrestrial acidification and air fine particulate matter formation. However, the efficiency of this technology has been found to depend on local environmental and regulatory conditions. The current study compared two slurry treatment options (no treatment versus slurry acidification in storage tanks) under the climatic, agronomic and legislative conditions found in Denmark, the Netherlands and Spain using Life Cycle Assessment (LCA). Data for the LCA model was collected from various sources and emissions following field application and crop yields were simulated over a 100-year period using the Daisy agricultural model. To address the uncertainty in LCA modelling, parameter analyses and Monte Carlo simulations with 1000 iterations were conducted followed by pairwise statistical tests. The results indicated that slurry acidification reduces the impact in all countries in impact categories mostly related to direct emissions from agriculture, such as methane and ammonia. For impact categories related to the provision of materials and energy to the farm, acidification increased the impacts in some cases. Additional requirements for lime application to counteract potential soil acidification did not result in significant changes in the performance of slurry acidification. The sulphur in the applied acid as an alternative to mineral S fertiliser can in some cases reduce the environmental impact of slurry acidification, but should not be advertised as doing so per se. Introducing stricter P application limits would seem to be the preferred option compared with slurry acidification in the Netherlands, while the opposite appeared true for Denmark.

Evaluating California dairy methane emission factors using short-term ground-level and airborne measurements

Robust air pollutant emission reduction strategies rely on accurate source characterizations. Studies have reported that the methane (CH 4 ) emissions from California’s dairy sector are highly variable, and raised questions regarding the representativeness of the statewide CH 4 emission estimates. To address these questions, a multi-tiered field study was conducted to evaluate the dairy CH 4 emission factors (EFs) used in the California Air Resources Board (CARB) emission inventory. These EFs for dairy cow enteric fermentation and anaerobic lagoons are 144 and 332 kg of CH 4 per animal head per year. CH 4 emissions from dairies located within the San Joaquin Valley (SJV) were characterized through the analysis of ground-level mobile measurements collected in the summer and the fall of 2019. We developed a novel dispersion modeling-based approach that uses the ground-level mobile measurements of ambient CH 4 levels to generate a metric that evaluates the CARB CH 4 EFs. The analysis was further expanded using airborne measurements collected between September 2017 and May 2020. The multi-tiered measurements resulted in 126 whole-farm CH 4 emission estimates for 107 dairies, making this study the most comprehensive mobile research study focused on CH 4 emissions from California dairies to date. CARB CH 4 EFs represented dairy CH 4 emissions captured in this study fairly well; emissions observed in ground-level mobile measurements in summer and fall, and airborne measurements were greater than the inventory-reported values by only 8% (95% Confidence Interval [CI 95% ]: -7%–31%), 3% (CI 95% : -11 – 21%), and 10% (CI 95% : -7 – 45%), respectively. The results underline the effects of meteorology on dairy emissions and suggest that CH 4 EFs from dairies with different ranges of herd sizes did not vary significantly. Future evaluation of the CARB CH 4 emission inventory must incorporate facility-level data and leverage mechanistic approaches that capture the temporal variation of emissions from California’s dairy farms. Such improvements would enable research studies to better inform the emission inventory and help track the emissions changes from the implementation of new manure management technologies across California. • Methane emissions from 107 California dairies were characterized. • The most comprehensive mobile study on California dairies methane emissions. • Emission factors used in the emission inventory explained the collected data well. • Meteorological parameters, e.g. temperature and wind speed, impact dairy emissions. • Facility-level data and process-based models can inform the emission inventory.

Promise and performance of agricultural nutrient management policy: Lessons from the Baltic Sea

Following decades of international collaboration to restore the Baltic Sea, we provide an assessment of the domestic implementation of measures agreed to limit diffuse agricultural pollution and the patterns of policy instruments applied. Despite the Helsinki Convention being unusually specific in detailing what measures countries should introduce, we find many shortcomings. These are most pronounced in the larger countries (Poland, Germany and Russia), while smaller countries perform better, notably Sweden and Estonia. The patterns of policy instruments applied differ, influenced by domestic politics. The limited use of complementary policy instruments suggests that other priorities overrule full and effective implementation, with engagement mirroring the advantages that a restored Baltic Sea can bring to countries. Using the European Agricultural Fund for Rural Development to support farmers in managing nutrients, particularly advisory services and investments in modern manure management technologies, represents a significant opportunity for reducing agricultural pollution in most countries.

The impact of farm scale and technology characteristics on the adoption of sustainable manure management technologies: Evidence from hog production in China

A key strategy in reducing ecological damage from livestock manure is to improve farms’ adoption of sustainable manure management technologies (SMMTs). However, designing policies to promote SMMTs’ adoption is challenging due to the heterogeneity in farm scale and technology characteristics. Based on a questionnaire-based survey of 686 hog farms in the Poyang Lake Region—one of the biggest ecological wetlands in Asia and the largest freshwater lakes in China, this paper adopted a multivariate probit model to empirically investigate the impact of farm scale and technology characteristics on SMMTs’ adoption. The results show that there is significant heterogeneity in the SMMTs’ adoption across farm scales. Small-scale farms are more likely to adopt land-intensive and labor-intensive SMMTs, while medium-scale and large-scale farms are more likely to adopt capital-intensive and knowledge-intensive SMMTs. The main determinants of the adoption heterogeneity can be explained by the characteristics of farm and technology in labor, capital, land, and knowledge. Small-scale farms’ decision to adopt SMMTs is mostly associated with labor availability and land area; variables expressing capital constraints have the highest effect on medium-scale farms’ decision to adopt SMMTs, while land area is the key constraint for large-scale farms to choose SMMTs. We suggest that policies designed to promote SMMTs’ adoption need to be carefully planned and tailored to different scales of farms rather than being standardized.

A critical review on livestock manure biorefinery technologies: Sustainability, challenges, and future perspectives

An ever increasing demand for animal protein products has posed serious challenges for managing the increasing quantities of livestock manure. The choice of treatment technologies is still a complicated task and considerable debates over this issue still continue. To build a clearer picture of manure treatment framework, this study was conducted to review the most frequently employed manure management technologies from their state of the art, challenges, sustainability, environmental regulations and incentives, and improvement strategies perspectives. The results showed that most treatment technologies have focused on the solid fraction of manure while the liquid fraction still remains a potential environmental threat. Compared to other waste to energy solutions, anaerobic digestion is the most mature technology to upgrade manure's organic matter into renewable energy, however the problems associated with high investment costs, operating parameters, manure collection, and digestate management have hindered its developments in rural areas in developing countries. Bio-oil production through hydrothermal liquification is also a promising solution, as it can directly convert the wet manure into biofuel. However, lipid-poor nature of manure, operational difficulties, and the need for downstream process to remove nitrogenous compounds from the final product necessitate further research. Livestock manure management (both solid and liquid fractions) under biorefinery approach seems an inevitable solution for future sustainable development to meet circular bioeconomy requirements. Much research is still required to establish a systematic framework based on regional requirements to develop an integrated manure nutrient recycling and manure management planning with minimum environmental risks and maximum profit.

Assessment of a Cattle Manure Vermicomposting System Using Material Flow Analysis: A Case Study from Uganda

Growth in cattle population is associated with increased manure generation whose current management in low-income countries is associated with health and environmental problems as well as low utilization rates. This trend can be reversed by promoting better manure management technologies. This study assessed vermicomposting as one of the technologies to manage organic wastes, using the case study in Uganda. A vermicomposting system using cattle manure and earthworms (Eudrilus euginea) was monitored for one year with the harvesting of products (compost, earthworm biomass) after every three months. Vermicompost samples from the beginning of the experiment and after every harvest were analyzed for the following parameters: pH, ash content, volatile and total solids, nutrients N, P, K, and C. Emissions of CO2, CH4, NH3, and N2O were also measured. Material flow analysis was used to determine the flows and retention of nutrients within the system. Results showed that total solids, ash, N, P, and K content significantly increased, while contents of volatile solids and C, as well as the pH, significantly decreased over time. Of the materials that entered the vermicomposting system, 46% went to vermicompost, 2% into earthworms, and 52% was lost to the atmosphere. Substance flow analysis showed that 30% of C went to vermicompost, 69% was emitted to the atmosphere, and 2% ended up in earthworms while 75% of N was transferred to vermicompost, 7% went to earthworms, and 18% escaped into the atmosphere. The cumulative emissions were 102 g CO2 kg−1 waste, 7.6 g CH4 kg−1 waste, and 3.943 × 10−5 g N2O kg−1 waste on a dry basis, while NH3 was not detected throughout the measurement time. Compared to other manure management methods, vermicomposting demonstrated good potential in conserving nutrients as well as reducing greenhouse gas emissions.

Methods for the Treatment of Cattle Manure—A Review

Environmental concerns, caused by greenhouse gases released to the atmosphere and overrunning of nutrients and pathogens to water bodies, have led to reducing direct spread onto the land of cattle manure. In addition, this practice can be a source of water and air pollution and toxicity to life by the release of undesirable heavy metals. Looking at the current practices, it is evident that most farms separate solids for recycling purposes, store slurries in large lagoons or use anaerobic digestion to produce biogas. The review explores the potential for cattle manure as an energy source due to its relatively large calorific value (HHV of 8.7–18.7 MJ/kg dry basis). This property is beneficial for thermochemical conversion processes, such as gasification and pyrolysis. This study also reviews the potential for upgrading biogas for transportation and heating use. This review discusses current cattle manure management technologies—biological treatment and thermochemical conversion processes—and the diverse physical and chemical properties due to the differences in farm practices.

Integrated manure management to reduce environmental impact: I. Structured design of strategies

Management of animal manure in livestock and crop production is a major cause of nitrogen (N), phosphorus (P), and carbon (C) loss. The losses of N, P, and C contribute to adverse environmental impacts, such as climate change, terrestrial acidification, and marine eutrophication. Manure management technologies to reduce losses and impacts have been developed, but often focus on a single compound only or a single stage in the management system and lead to trade-offs, such as pollution swapping. The aim of this study was to design strategies for integrated manure management (IS) which prevent pollution swapping and show that the environmental impact can be reduced throughout the manure management system. We used a structured design approach based on engineering design (ED) that consists of eight main steps: 1. define the goal of the design task and the system boundaries, 2. formulate a brief of requirements stating the needs for environmental reduction, 3. analyze the functions in the current manure management system, 4. list and describe emission processes and their process variables that lead to N, P, and C losses and resource use, 5. describe the functions needed in the manure management system to limit the emission processes or resource use, 6. generate principle-options that can fulfill the functions, 7. generate technical solutions for the principle-options, and 8. combine the principle-options and technical solutions into strategies for integrated manure management. In the design of strategies we considered the management of liquid and solid dairy cattle manure applied to grass and maize, and liquid pig manure applied to wheat, all under North West European conditions. The IS included the segregation of pig and dairy cattle urine and feces to reduce CH4, NH3, and N2O emission, addition of zeolite to solid cattle manure to reduce NH3 emission, bio-energy production from biogas that avoids fossil-based electricity and heat, acidification of urine during storage and acidification of feces prior to application, sealed storages, and improved application timing, place, and method of application. It was concluded that we were able to successfully design IS with high potential to reduce environmental impact. The design approach adapted from ED proved to be useful to structure the design process to provide insight into interactions of emission processes and find principle-options and technical solutions to prevent pollution swapping.

Managing Manure from China’s Pigs and Poultry: The Influence of Ecological Rationality

We have investigated manure management practices at three farm scales in Chinese pig and poultry production. The concept of ecological rationality was employed to explore empirically how environmental concerns drive adoption of environmental-friendly manure management technologies at different farm scales. The more developed Rudong County in Jiangsu Province and the less developed Zhongjiang County in Sichuan Province were chosen as cases for study of 258 animal breeders. On the contrary to our hypothesis, medium-scale farmers were not always found to be laggards in adoption of manure management technologies. Government ecological rationality played a key role to induce environmental-friendly technology adoption on its own, but also in cooperation with ecologically rational individual or network drivers. Authorities no longer applied their efforts in a conventional command-and-control way, but more in the form of incentives, stimulation, and information to farmers. Individual farmers in general showed low environmental responsibility in relation to manure handling.

Regional analysis of greenhouse gas emissions from USA dairy farms: A cradle to farm-gate assessment of the American dairy industry circa 2008

Greenhouse gas (GHG) emissions were evaluated from crop production through the on-farm portion of the milk supply chain for five production regions in the USA derived from publicly available data and from 536 surveys of farm operations collected from dairy operations nationwide. The production weighted national average footprint at the farm gate was 1.23 kg carbon dioxide equivalent (CO2e) per kg of fat and protein corrected milk (fat, 4%; protein 3.3%). Regional differences in GHG emissions per kg milk produced can be primarily traced to differences in production and management practices. Feed-to-milk conversion efficiency is shown to be the single most important explanatory variable, followed by choice of manure management technology. While there is no one-size-fits-all solution, GHG emissions reduction opportunities exist across the spectrum of dairy management options. However, as with all decisions, it is important to weigh potential trade-offs with other environmental and economic impacts.

Manure management practices on biogas and non-biogas pig farms in developing countries – using livestock farms in Vietnam as an example

This survey was carried out to study animal manure management on livestock farms with biogas technology (biogas farms) and without (non-biogas farms) in the areas surrounding the Vietnamese cities Hanoi and Hue. The objective of the study was to assess the contribution of biogas production to a better environment as well as to recognize the problems with livestock manure management on small-scale farms. On all the farms included in the study more than one manure management technology was used, i.e. composting, separation of manure, biogas production and discharge of liquid manure to recipients such as public sewers or ponds. On biogas farms, most of the manure collected was used for bio-digestion. The farmers used the fermented manure (digestate) as a source of nutrients for crops, but on more than 50% of the interviewed biogas farms digestate was discharged to the environment. On non-biogas farms, manure was in the form of slurry or it was separated into a liquid and a dry-matter-rich solid fraction. The solid fraction from separation was used for composting and the liquid fraction usually discharged to the environment. The survey revealed that there is a need to improve methods for transporting the manure to the field, as transportation is the main barrier to recycling the liquid manure fraction. Farmers in developing countries need financial and technical support to install biogas digesters and to overcome the problems involved in utilizing the manure. Information about how to pre-treat manure before adding it to the digester is urgently needed. At present too much water is used, and the high volume of slurry reduces the retention time and is a disincentive for transporting and applying the digestate to fields. The users need to be informed about the risk of loss of methane to the environment, how to prevent cooker corrosion and the discharge to recipients. In addition, the study reveals that in developing countries manure management legislation needs to be tightened to control environmental pollution.

Effects of cattle and manure management on the nutrient economy of mixed farms in East Africa: A scenario study

This paper explores effects of animal and manure management in a dairy unit on the nutrient economy of crop-livestock farms in East Africa. For this purpose, 8 cattle management scenarios have been developed based on farming systems in Mbeere, Kenya (extensive), Wakiso, Uganda (semi-intensive) and Kibichoi, Kenya (intensive). Three baseline scenarios represent present-day cattle management; five improved scenarios use the same dairy breeds but have improved nutrition, using younger grass, more legumes and moderate amounts of concentrates. These improvements strongly increase milk production per cow, but also N, P and K excretion in manure. The 8 cattle management scenarios are combined with 2 levels of manure management technology: a baseline technology, reflecting actual manure management and related losses of plant nutrients, and an improved technology with lower losses. Nutrient losses for each technology level have been derived from a thorough analysis of published information. This showed that current systems of collection and storage of the excreta of confined dairy cows are associated with large nutrient losses, in particular of N. These losses cause serious deficits on the N, P and K balances of the crop-livestock farms. Therefore, significant external N, P and K inputs and better manure management are required to sustain the production levels assumed and to avoid further soil fertility depletion in the region. The paper identifies several possibilities for this and concludes that there is a strong need for integral on-farm studies aiming at development of sustainable dairy production systems.