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Toward agricultural sustainability through integrated crop-livestock systems: Environmental outcomes
G Model
ARTICLE IN PRESS
AGEE-4723; No. of Pages 3
Agriculture, Ecosystems and Environment xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Agriculture, Ecosystems and Environment journal homepage: www.elsevier.com/locate/agee
Introduction
Toward agricultural sustainability through integrated crop-livestock systems: Environmental outcomes
1. Background and rationale Livestock production on grasslands associated with cereal and vegetable cropping on arable lands was the historical basis of the agricultural revolution that helped shape western civilization during the 16th century in Europe. The process of recycling organic matter and nutrients from livestock feces to cropland and through various fodders consumed by livestock created a relatively closed loop that sustained – and sometimes improved – soil fertility. However with the advancement of the industrial revolution, particularly in the mid-20th century with widespread use of synthetic fertilizers, reliance on mechanical power for field operations, and improved buildings and equipment for livestock wintering, feeding and milking, interest soon waned for such mixed farming systems. Livestock systems tended to become concentrated to capture economy of scale. Cropping systems became narrowly specialized to capture market opportunities and reduce labor requirements. As a result of these rapid technological changes, livestock production and arable cropping systems became increasingly separated onto different farms – and even in different regions – leading to unusual uniformity of regional agricultural landscapes. Intensification of these two types of specialized agricultural systems has led to unacceptable deterioration of the environment due to (i) excessive concentration of nutrients and pathogens in livestock production systems and (ii) loss of natural biodiversity and excessive simplification of ecosystem processes with uniform land use in arable cropping systems. Facing the necessity to increase agricultural production for a burgeoning human population, it will not be socially and economically acceptable to advocate for a decrease in agricultural productivity just to minimize negative environmental consequences of specialized agricultural systems (Foley et al., 2011). Our hypothesis is that by maintaining or enhancing diversity of agricultural systems – at all levels of organization, i.e. the field, the farm, the landscape, and the region – it will be possible to reconcile the seemingly dichotomous goals for achieving high quantity and quality of food production and improve environmental quality. Agricultural diversity at the field, farm, landscape, and regional levels may need to be simply maintained in less developed regions and improved in various ways and scales in more developed regions (NRC, 2010). The high capacity of grassland ecosystems for feeding domestic herbivores – and for producing essential ecosystem services,
such as CO2 sequestration, soil fertility, water quality, biodiversity – when associated spatially and temporally with arable cropping systems is an essential foundation for integrated crop-livestock systems (ICLS), either within single farms or among specialized farms within a region. Analysis of ICLS at farm or regional levels requires studies on processes governing biogeochemical cycles, environmental fluxes, and dynamics of biodiversity in interaction with management options. In this way, it will be possible to answer the question “What if. . .?” and to evaluate the impacts of systems both in term of production and ecosystem services. Development and adoption of ICLS by farmers implies the need for entrepreneurial evaluation of system types and analyses of socioeconomic constraints to answer the question “What is it necessary for. . .?” Hence, advancement of modern ICLS as a concept to promote agricultural productivity and achieve environmental quality will require a multidisciplinary approach linking strongly processbased and system-management analyses from local to regional scales. An international effort to move ICLS forward as an agricultural sustainability concept has been gaining traction through a series of symposia – the first of which occurred in Curitiba Brazil in August 2007 and the second of which occurred in Porto Alegre Brazil in October 2012. The first symposium was organized by the Federal University of Parana (UFPR) and was divided into invited oral sessions focused on (i) the fundamental concept, (ii) the crop component, (iii) the soil component, (iv) the animal component, and (v) a world-wide context. Many volunteered posters were also presented, primarily by researchers in Brazil and neighboring Latin American countries and a tour of research stations and farms in Parana was organized. The second symposium was organized by the Federal University of Rio Grande do Sul (UFRGS) organized into themes of (i) introduction and summaries of ICLS in different regions of the world, (ii) ecological and environmental processes from fields to landscapes, (iii) issues and tools for integration between livestock and arable cropping systems, (iv) long-term experimental platforms for quantification and prediction of impacts from land use and climate change, (v) management and policies for ICLS at farm to regional levels, and (vi) summary comments. Invited speakers came from nine countries, many posters were presented from research being conducted primarily in South America, and a mid-week tour of farms using ICLS principles was organized. From the enthusiasm and success of the first two symposia, a third symposium is already being planned for 2015.
http://dx.doi.org/10.1016/j.agee.2014.04.028 0167-8809/Published by Elsevier B.V.
Please cite this article in press as: Franzluebbers, A.J., et al., Toward agricultural sustainability through integrated crop-livestock systems: Environmental outcomes. Agric. Ecosyst. Environ. (2014), http://dx.doi.org/10.1016/j.agee.2014.04.028
G Model AGEE-4723; No. of Pages 3 2
ARTICLE IN PRESS Introduction / Agriculture, Ecosystems and Environment xxx (2014) xxx–xxx
Publication from the first symposium was as proceedings papers on CD-ROM. From the 2nd International Symposium on Integrated Crop-Livestock Systems, we wanted to reach a broader scientific community, and therefore, organized a series of three special issues in international journals under the following general themes: I. Environmental outcomes (special issue in Agriculture, Ecosystems and Environment) II. Production responses (special section in European Journal of Agronomy) III. Social aspects (special section in Renewable Agriculture and Food Systems) 2. Environmental outcomes of integrated crop-livestock systems Fifteen papers from the symposium in Porto Alegre are presented in this issue and summarized in the following. In the introductory article by Lemaire et al., rationale is outlined for increasing biodiversity in the agricultural landscape to better regulate biogeochemical cycles and decrease environmental fluxes to the atmosphere and hydrosphere, to create a more diversified and structured landscape mosaic that would favor diverse habitats and trophic networks, and to cope with potential socio-economic and climate induced hazards and crises. Soussana and Lemaire described the coupling of C and N in grassland ecosystems. Moderate intensification of grasslands with fertilization and stocking density results in optimal balance between production and environmental quality; excessive intensification decouples carbon and nitrogen and leads to unacceptable environmental risks. Franzluebbers et al. reviewed literature from North and South America to show that strong positive production outcomes of crops can be obtained following rotation with pastures, enhancement of soil organic matter can be achieved with perennial pastures in rotation, improvement in water infiltration and water quality can be expected with protective surface cover of pastures, and synergies can be obtained between crop and livestock systems in systemwide evaluations of production and environmental quality. Two studies focused on the impacts of livestock grazing on potentially greater nutrient availability. Cicek et al. reported soil nitrate, crop growth, and grain yield responses in multi-year experiments carried out to assess the effect of grazing summer cover crops in Manitoba Canada. Soil nitrate was greater following grazed than ungrazed cover crops, which led to greater crop growth and N uptake in some years, but no differences in wheat grain yield. Grazing cover crops appeared to stimulate N turnover without negatively affecting subsequent grain crops. Assmann et al. documented the change in nutrient availability of the residues of a wheat cover crop that were grazed at different intensities in Parana, Brazil. In integrated crop-livestock systems, the quantity of residual forage mass at the end of the grazing season would have much greater impact on nutrient cycling than plant litter quality of that residue. Grazing of winter wheat cover crop tended to have negative consequences on subsequent soybean grain yield. Three studies reported on the long-term effects of grazing intensity on soil C, N, and P. Costa et al. quantified the effect of cropping system on soil P fractions at the end of 6 years of field experimentation in Rio Grande do Sul, Brazil. Total soil P increased in both grazed and ungrazed systems. Integrated crop-livestock system with winter grazing of black oat/ryegrass cover crop led to greater labile P stocks, both in organic and inorganic forms. Grazing led to P budget surplus and more efficient P use, as represented by additional livestock gain compared with soybean production only. In this same study, Assman et al. evaluated the stocks of soil organic C and N at
the end of 9 years of this study. Moderate and light grazing intensities (i.e. 20–40 cm height) had greater total organic C, particulate organic C, total N, and particulate organic N than ungrazed winter cover crop and highest intensity grazing (i.e. forage maintained at 10 cm height). Silva et al. evaluated several C indices at the end of 10 years of this study. Soil organic C was linearly related with C stratification ratio, C management index, and C pool index. Winter cover crop managed at a height between 20 and 40 cm had the best balance between the C management index and animal daily gain. Optimization of the C management index and livestock gain per hectare occurred with a sward height of 20 cm. Salton et al. reviewed the results of a long-term field study in Mato Grosso do Sul, Brazil. Cropping systems were conventional tillage, no tillage, integrated crop-livestock systems with 2-year rotation, and permanent Brachiaria pasture. More complex and diversified production systems exhibited better soil physical structure, greater efficiency in use of nutrients by plants, greater accumulation of labile fractions of soil organic matter, greater diversity and biological activity in soil, and lower occurrence of nematodes and weeds. The integrated crop-livestock system was efficient at accumulating soil organic C and reducing emissions of greenhouse gases. Soil quality was improved in more complex cropping systems than simple systems. Boeni et al. evaluated soil organic matter composition changes in three long-term cropping system studies in the Cerrado region of Brazil. In general, perennial pastures had greatest concentration of total organic C and in various physical fractions, while integrated crop-livestock systems had intermediate levels and continuous cropping had lowest concentrations. Organic C was distributed unequally, with 7% in the free light fraction, 26% in the occluded light fraction, and 67% in the heavy fraction. Carbon types followed the order: O-alkyl > aromatic > carboxyl. Biomass addition and soil disturbance were key determinants of soil organic C change. Greenhouse gas emissions were evaluated in four studies of livestock and livestock feces in Brazil. Piva et al. studied greenhouse gas emissions and soil organic C stock at the end of a 3 year study comparing double cropping with and without winter grazing in Parana, Brazil. Annual N2 O emission was greater from the grazed than ungrazed system. N2 O emission from animal excreta was also evaluated. Soil emission of CH4 was not affected by cropping system. Soil organic C stock was unaffected, possibly due to the relatively short-term nature of the field study. Sordi et al. evaluated greenhouse gas emissions from cattle feces during summer, winter, and spring periods in Parana, Brazil. Calculated emission factor of N2 O–N for urine was greater than that of dung due to greater availability of urea-N than organic N forms from dung. Lessa et al. also determined volatile losses of N from urine and dung during the tropical dry and wet seasons in Goias, Brazil. Urine had greater proportions of N lost as N2 O and NH3 than dung. Although the total quantity of NH3 volatilization was similar between dry and wet seasons, the temporal dynamic was different. Emission of N2 O was greater during the wet than the dry season. Savian et al. determined CH4 emissions from sheep grazing at low and moderate grazing intensity and with continuous and rotational stocking in Rio Grande do Sul, Brazil. Methane emissions per animal were not affected by treatments, but rotational stocking led to greater CH4 emissions per unit of livestock weight gain than continuous stocking. Stocking method was more important in affecting CH4 emission from sheep than grazing intensity. Finally, Havet et al. evaluated the factors affecting production, environmental, and socioeconomic considerations in six different case studies of farming systems with various degrees of integration of crops and livestock in France. Indications for greater sustainability were detected with integration of crops and livestock; farm collaboration was also important in some cases.
Please cite this article in press as: Franzluebbers, A.J., et al., Toward agricultural sustainability through integrated crop-livestock systems: Environmental outcomes. Agric. Ecosyst. Environ. (2014), http://dx.doi.org/10.1016/j.agee.2014.04.028
G Model AGEE-4723; No. of Pages 3
ARTICLE IN PRESS Introduction / Agriculture, Ecosystems and Environment xxx (2014) xxx–xxx
In conclusion, this special issue highlights the need for biologically diverse farms and landscapes to buffer against environmental degradation that can be caused by conventional agricultural systems. Synergies between crop and livestock are possible to capture and retain carbon in ecologically relevant forms to synchronize nutrient releases efficiently with biological demands. Some of this research has shown the possibilities for improving nutrient cycling by enhancing soil carbon storage, but further research is needed to understand the complexities of interactions occurring in ICLS. We hope this special issue will be insightful for designing research to sustain agriculture into the future to address critical issues of nutrient supply limitations, energy constraints, human population demands, climate change threats, etc. Acknowledgements We thank the sponsors of the 2nd International Symposium on Integrated Crop-Livestock Systems: Ministry of Education (http://www.mec.gov.br/), Ministry of Agriculture, Livestock and Food Supply (http://www.agricultura.gov.br/), Government of Brazil (http://www.brasil.gov.br/), Rio Grande Institute of Rice (http://www.irga.rs.gov.br/), Secretariat of Agriculture, Livestock and Agribusiness (http://www.agricultura.rs.gov.br/), Program to Compete Together (Juntos Para Competir), FARSUL (http://www. farsul.org.br/), SENAR (http://www.canaldoprodutor.com.br/ internacional/senar), SEBRAE (http://www.sebrae.com.br/), CAPES (http://www.capes.gov.br/), CNPq (http://www.cnpq.br/), Agrisus (http://www.agrisus.org.br/), FAO (http://www.fao.org/), USDAAgricultural Research Service (http://www.ars.usda.gov/), CIRAD (http://www.cirad.fr/), MARFRIG (http://www.marfrig.com.br/), INRA (http://www.inra.fr/), Federal University of Parana (http://www.ufpr.br/), and Federal University of Rio Grande do Sul (http://www.ufrgs.br/).We also thank the participants of the symposium for bringing their ideas up for discussion. We thank the authors of these papers for working diligently to assemble high-quality contributions and we thank the many reviewers who devoted their time and expertise to note deficiencies in
3
presentations and to suggest improvements. We hope that this set of special issues is the beginning of fruitful research and development among scientific colleagues and with industry partners to improve agriculture for the benefit of humankind. References Foley, J.A., Ramankutty, N., Brauman, K.A., Cassidy, E.S., Gerber, J.S., Johnston, M., Mueller, N.D., O’Connell, C., Ray, D.K., West, P.C., Balzer, C., Bennett, E.M., Carpenter, S.R., Hill, J., Monfreda, C., Polasky, S., Rockström, J., Sheehan, J., Siebert, S., Tilman, D., Zaks, D.P.M., 2011. Solutions for a cultivated planet. Nature 478, 337–342. NRC (National Research Council), 2010. Toward sustainable agricultural systems in the 21st century. Committee on Twenty-First Century Systems Agriculture. The National Academies Press, Washington, DC, pp. 570.
Alan J. Franzluebbers ∗ USDA – Agricultural Research Service, NCSU Campus Box 7619, Raleigh, NC 27695, USA Gilles Lemaire INRA, Unité Pluridisciplinaire Prairies et Plantes Fourragères, Lusignan 86600, France Paulo César de Faccio Carvalho UFRGS, Av. Bento Gonc¸alves 7712, 91540-000 Porto Alegre, Brazil R. Mark Sulc Ohio State University, 2021 Coffey Road, Columbus, OH 43210-1086, USA Benoît Dedieu INRA Sciences pour l’Action et le Développement, Theix 63122 Saint Genès Champanelle, France ∗ Corresponding author. E-mail address: [email protected] (A.J. Franzluebbers)
Available online xxx
Please cite this article in press as: Franzluebbers, A.J., et al., Toward agricultural sustainability through integrated crop-livestock systems: Environmental outcomes. Agric. Ecosyst. Environ. (2014), http://dx.doi.org/10.1016/j.agee.2014.04.028
ARTICLE IN PRESS
AGEE-4723; No. of Pages 3
Agriculture, Ecosystems and Environment xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Agriculture, Ecosystems and Environment journal homepage: www.elsevier.com/locate/agee
Introduction
Toward agricultural sustainability through integrated crop-livestock systems: Environmental outcomes
1. Background and rationale Livestock production on grasslands associated with cereal and vegetable cropping on arable lands was the historical basis of the agricultural revolution that helped shape western civilization during the 16th century in Europe. The process of recycling organic matter and nutrients from livestock feces to cropland and through various fodders consumed by livestock created a relatively closed loop that sustained – and sometimes improved – soil fertility. However with the advancement of the industrial revolution, particularly in the mid-20th century with widespread use of synthetic fertilizers, reliance on mechanical power for field operations, and improved buildings and equipment for livestock wintering, feeding and milking, interest soon waned for such mixed farming systems. Livestock systems tended to become concentrated to capture economy of scale. Cropping systems became narrowly specialized to capture market opportunities and reduce labor requirements. As a result of these rapid technological changes, livestock production and arable cropping systems became increasingly separated onto different farms – and even in different regions – leading to unusual uniformity of regional agricultural landscapes. Intensification of these two types of specialized agricultural systems has led to unacceptable deterioration of the environment due to (i) excessive concentration of nutrients and pathogens in livestock production systems and (ii) loss of natural biodiversity and excessive simplification of ecosystem processes with uniform land use in arable cropping systems. Facing the necessity to increase agricultural production for a burgeoning human population, it will not be socially and economically acceptable to advocate for a decrease in agricultural productivity just to minimize negative environmental consequences of specialized agricultural systems (Foley et al., 2011). Our hypothesis is that by maintaining or enhancing diversity of agricultural systems – at all levels of organization, i.e. the field, the farm, the landscape, and the region – it will be possible to reconcile the seemingly dichotomous goals for achieving high quantity and quality of food production and improve environmental quality. Agricultural diversity at the field, farm, landscape, and regional levels may need to be simply maintained in less developed regions and improved in various ways and scales in more developed regions (NRC, 2010). The high capacity of grassland ecosystems for feeding domestic herbivores – and for producing essential ecosystem services,
such as CO2 sequestration, soil fertility, water quality, biodiversity – when associated spatially and temporally with arable cropping systems is an essential foundation for integrated crop-livestock systems (ICLS), either within single farms or among specialized farms within a region. Analysis of ICLS at farm or regional levels requires studies on processes governing biogeochemical cycles, environmental fluxes, and dynamics of biodiversity in interaction with management options. In this way, it will be possible to answer the question “What if. . .?” and to evaluate the impacts of systems both in term of production and ecosystem services. Development and adoption of ICLS by farmers implies the need for entrepreneurial evaluation of system types and analyses of socioeconomic constraints to answer the question “What is it necessary for. . .?” Hence, advancement of modern ICLS as a concept to promote agricultural productivity and achieve environmental quality will require a multidisciplinary approach linking strongly processbased and system-management analyses from local to regional scales. An international effort to move ICLS forward as an agricultural sustainability concept has been gaining traction through a series of symposia – the first of which occurred in Curitiba Brazil in August 2007 and the second of which occurred in Porto Alegre Brazil in October 2012. The first symposium was organized by the Federal University of Parana (UFPR) and was divided into invited oral sessions focused on (i) the fundamental concept, (ii) the crop component, (iii) the soil component, (iv) the animal component, and (v) a world-wide context. Many volunteered posters were also presented, primarily by researchers in Brazil and neighboring Latin American countries and a tour of research stations and farms in Parana was organized. The second symposium was organized by the Federal University of Rio Grande do Sul (UFRGS) organized into themes of (i) introduction and summaries of ICLS in different regions of the world, (ii) ecological and environmental processes from fields to landscapes, (iii) issues and tools for integration between livestock and arable cropping systems, (iv) long-term experimental platforms for quantification and prediction of impacts from land use and climate change, (v) management and policies for ICLS at farm to regional levels, and (vi) summary comments. Invited speakers came from nine countries, many posters were presented from research being conducted primarily in South America, and a mid-week tour of farms using ICLS principles was organized. From the enthusiasm and success of the first two symposia, a third symposium is already being planned for 2015.
http://dx.doi.org/10.1016/j.agee.2014.04.028 0167-8809/Published by Elsevier B.V.
Please cite this article in press as: Franzluebbers, A.J., et al., Toward agricultural sustainability through integrated crop-livestock systems: Environmental outcomes. Agric. Ecosyst. Environ. (2014), http://dx.doi.org/10.1016/j.agee.2014.04.028
G Model AGEE-4723; No. of Pages 3 2
ARTICLE IN PRESS Introduction / Agriculture, Ecosystems and Environment xxx (2014) xxx–xxx
Publication from the first symposium was as proceedings papers on CD-ROM. From the 2nd International Symposium on Integrated Crop-Livestock Systems, we wanted to reach a broader scientific community, and therefore, organized a series of three special issues in international journals under the following general themes: I. Environmental outcomes (special issue in Agriculture, Ecosystems and Environment) II. Production responses (special section in European Journal of Agronomy) III. Social aspects (special section in Renewable Agriculture and Food Systems) 2. Environmental outcomes of integrated crop-livestock systems Fifteen papers from the symposium in Porto Alegre are presented in this issue and summarized in the following. In the introductory article by Lemaire et al., rationale is outlined for increasing biodiversity in the agricultural landscape to better regulate biogeochemical cycles and decrease environmental fluxes to the atmosphere and hydrosphere, to create a more diversified and structured landscape mosaic that would favor diverse habitats and trophic networks, and to cope with potential socio-economic and climate induced hazards and crises. Soussana and Lemaire described the coupling of C and N in grassland ecosystems. Moderate intensification of grasslands with fertilization and stocking density results in optimal balance between production and environmental quality; excessive intensification decouples carbon and nitrogen and leads to unacceptable environmental risks. Franzluebbers et al. reviewed literature from North and South America to show that strong positive production outcomes of crops can be obtained following rotation with pastures, enhancement of soil organic matter can be achieved with perennial pastures in rotation, improvement in water infiltration and water quality can be expected with protective surface cover of pastures, and synergies can be obtained between crop and livestock systems in systemwide evaluations of production and environmental quality. Two studies focused on the impacts of livestock grazing on potentially greater nutrient availability. Cicek et al. reported soil nitrate, crop growth, and grain yield responses in multi-year experiments carried out to assess the effect of grazing summer cover crops in Manitoba Canada. Soil nitrate was greater following grazed than ungrazed cover crops, which led to greater crop growth and N uptake in some years, but no differences in wheat grain yield. Grazing cover crops appeared to stimulate N turnover without negatively affecting subsequent grain crops. Assmann et al. documented the change in nutrient availability of the residues of a wheat cover crop that were grazed at different intensities in Parana, Brazil. In integrated crop-livestock systems, the quantity of residual forage mass at the end of the grazing season would have much greater impact on nutrient cycling than plant litter quality of that residue. Grazing of winter wheat cover crop tended to have negative consequences on subsequent soybean grain yield. Three studies reported on the long-term effects of grazing intensity on soil C, N, and P. Costa et al. quantified the effect of cropping system on soil P fractions at the end of 6 years of field experimentation in Rio Grande do Sul, Brazil. Total soil P increased in both grazed and ungrazed systems. Integrated crop-livestock system with winter grazing of black oat/ryegrass cover crop led to greater labile P stocks, both in organic and inorganic forms. Grazing led to P budget surplus and more efficient P use, as represented by additional livestock gain compared with soybean production only. In this same study, Assman et al. evaluated the stocks of soil organic C and N at
the end of 9 years of this study. Moderate and light grazing intensities (i.e. 20–40 cm height) had greater total organic C, particulate organic C, total N, and particulate organic N than ungrazed winter cover crop and highest intensity grazing (i.e. forage maintained at 10 cm height). Silva et al. evaluated several C indices at the end of 10 years of this study. Soil organic C was linearly related with C stratification ratio, C management index, and C pool index. Winter cover crop managed at a height between 20 and 40 cm had the best balance between the C management index and animal daily gain. Optimization of the C management index and livestock gain per hectare occurred with a sward height of 20 cm. Salton et al. reviewed the results of a long-term field study in Mato Grosso do Sul, Brazil. Cropping systems were conventional tillage, no tillage, integrated crop-livestock systems with 2-year rotation, and permanent Brachiaria pasture. More complex and diversified production systems exhibited better soil physical structure, greater efficiency in use of nutrients by plants, greater accumulation of labile fractions of soil organic matter, greater diversity and biological activity in soil, and lower occurrence of nematodes and weeds. The integrated crop-livestock system was efficient at accumulating soil organic C and reducing emissions of greenhouse gases. Soil quality was improved in more complex cropping systems than simple systems. Boeni et al. evaluated soil organic matter composition changes in three long-term cropping system studies in the Cerrado region of Brazil. In general, perennial pastures had greatest concentration of total organic C and in various physical fractions, while integrated crop-livestock systems had intermediate levels and continuous cropping had lowest concentrations. Organic C was distributed unequally, with 7% in the free light fraction, 26% in the occluded light fraction, and 67% in the heavy fraction. Carbon types followed the order: O-alkyl > aromatic > carboxyl. Biomass addition and soil disturbance were key determinants of soil organic C change. Greenhouse gas emissions were evaluated in four studies of livestock and livestock feces in Brazil. Piva et al. studied greenhouse gas emissions and soil organic C stock at the end of a 3 year study comparing double cropping with and without winter grazing in Parana, Brazil. Annual N2 O emission was greater from the grazed than ungrazed system. N2 O emission from animal excreta was also evaluated. Soil emission of CH4 was not affected by cropping system. Soil organic C stock was unaffected, possibly due to the relatively short-term nature of the field study. Sordi et al. evaluated greenhouse gas emissions from cattle feces during summer, winter, and spring periods in Parana, Brazil. Calculated emission factor of N2 O–N for urine was greater than that of dung due to greater availability of urea-N than organic N forms from dung. Lessa et al. also determined volatile losses of N from urine and dung during the tropical dry and wet seasons in Goias, Brazil. Urine had greater proportions of N lost as N2 O and NH3 than dung. Although the total quantity of NH3 volatilization was similar between dry and wet seasons, the temporal dynamic was different. Emission of N2 O was greater during the wet than the dry season. Savian et al. determined CH4 emissions from sheep grazing at low and moderate grazing intensity and with continuous and rotational stocking in Rio Grande do Sul, Brazil. Methane emissions per animal were not affected by treatments, but rotational stocking led to greater CH4 emissions per unit of livestock weight gain than continuous stocking. Stocking method was more important in affecting CH4 emission from sheep than grazing intensity. Finally, Havet et al. evaluated the factors affecting production, environmental, and socioeconomic considerations in six different case studies of farming systems with various degrees of integration of crops and livestock in France. Indications for greater sustainability were detected with integration of crops and livestock; farm collaboration was also important in some cases.
Please cite this article in press as: Franzluebbers, A.J., et al., Toward agricultural sustainability through integrated crop-livestock systems: Environmental outcomes. Agric. Ecosyst. Environ. (2014), http://dx.doi.org/10.1016/j.agee.2014.04.028
G Model AGEE-4723; No. of Pages 3
ARTICLE IN PRESS Introduction / Agriculture, Ecosystems and Environment xxx (2014) xxx–xxx
In conclusion, this special issue highlights the need for biologically diverse farms and landscapes to buffer against environmental degradation that can be caused by conventional agricultural systems. Synergies between crop and livestock are possible to capture and retain carbon in ecologically relevant forms to synchronize nutrient releases efficiently with biological demands. Some of this research has shown the possibilities for improving nutrient cycling by enhancing soil carbon storage, but further research is needed to understand the complexities of interactions occurring in ICLS. We hope this special issue will be insightful for designing research to sustain agriculture into the future to address critical issues of nutrient supply limitations, energy constraints, human population demands, climate change threats, etc. Acknowledgements We thank the sponsors of the 2nd International Symposium on Integrated Crop-Livestock Systems: Ministry of Education (http://www.mec.gov.br/), Ministry of Agriculture, Livestock and Food Supply (http://www.agricultura.gov.br/), Government of Brazil (http://www.brasil.gov.br/), Rio Grande Institute of Rice (http://www.irga.rs.gov.br/), Secretariat of Agriculture, Livestock and Agribusiness (http://www.agricultura.rs.gov.br/), Program to Compete Together (Juntos Para Competir), FARSUL (http://www. farsul.org.br/), SENAR (http://www.canaldoprodutor.com.br/ internacional/senar), SEBRAE (http://www.sebrae.com.br/), CAPES (http://www.capes.gov.br/), CNPq (http://www.cnpq.br/), Agrisus (http://www.agrisus.org.br/), FAO (http://www.fao.org/), USDAAgricultural Research Service (http://www.ars.usda.gov/), CIRAD (http://www.cirad.fr/), MARFRIG (http://www.marfrig.com.br/), INRA (http://www.inra.fr/), Federal University of Parana (http://www.ufpr.br/), and Federal University of Rio Grande do Sul (http://www.ufrgs.br/).We also thank the participants of the symposium for bringing their ideas up for discussion. We thank the authors of these papers for working diligently to assemble high-quality contributions and we thank the many reviewers who devoted their time and expertise to note deficiencies in
3
presentations and to suggest improvements. We hope that this set of special issues is the beginning of fruitful research and development among scientific colleagues and with industry partners to improve agriculture for the benefit of humankind. References Foley, J.A., Ramankutty, N., Brauman, K.A., Cassidy, E.S., Gerber, J.S., Johnston, M., Mueller, N.D., O’Connell, C., Ray, D.K., West, P.C., Balzer, C., Bennett, E.M., Carpenter, S.R., Hill, J., Monfreda, C., Polasky, S., Rockström, J., Sheehan, J., Siebert, S., Tilman, D., Zaks, D.P.M., 2011. Solutions for a cultivated planet. Nature 478, 337–342. NRC (National Research Council), 2010. Toward sustainable agricultural systems in the 21st century. Committee on Twenty-First Century Systems Agriculture. The National Academies Press, Washington, DC, pp. 570.
Alan J. Franzluebbers ∗ USDA – Agricultural Research Service, NCSU Campus Box 7619, Raleigh, NC 27695, USA Gilles Lemaire INRA, Unité Pluridisciplinaire Prairies et Plantes Fourragères, Lusignan 86600, France Paulo César de Faccio Carvalho UFRGS, Av. Bento Gonc¸alves 7712, 91540-000 Porto Alegre, Brazil R. Mark Sulc Ohio State University, 2021 Coffey Road, Columbus, OH 43210-1086, USA Benoît Dedieu INRA Sciences pour l’Action et le Développement, Theix 63122 Saint Genès Champanelle, France ∗ Corresponding author. E-mail address: [email protected] (A.J. Franzluebbers)
Available online xxx
Please cite this article in press as: Franzluebbers, A.J., et al., Toward agricultural sustainability through integrated crop-livestock systems: Environmental outcomes. Agric. Ecosyst. Environ. (2014), http://dx.doi.org/10.1016/j.agee.2014.04.028