Accepted Manuscript

Mitigation of environmental impacts of beef cattle production in southern Brazil –evaluation using farm-based life cycle assessment

Milene Dick, Marcelo Abreu da Silva, Homero Dewes

PII: S0959-6526(14)01130-5

DOI: 10.1016/j.jclepro.2014.10.087

Reference: JCLP 4876

To appear in: Journal of Cleaner Production

Received Date: 12 April 2014

Revised Date: 27 October 2014

Accepted Date: 28 October 2014

Please cite this article as: Dick M, Abreu da Silva M, Dewes H, Mitigation of environmental impacts ofbeef cattle production in southern Brazil – evaluation using farm-based life cycle assessment, Journal ofCleaner Production (2014), doi: 10.1016/j.jclepro.2014.10.087.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service toour customers we are providing this early version of the manuscript. The manuscript will undergocopyediting, typesetting, and review of the resulting proof before it is published in its final form. Pleasenote that during the production process errors may be discovered which could affect the content, and alllegal disclaimers that apply to the journal pertain.

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

1

8274 words

Mitigation of environmental impacts of beef cattle production in southern Brazil – evaluation using farm-based life cycle assessment

Milene Dick1*, Marcelo Abreu da Silva2, Homero Dewes1, 3 1Center for Research in Agribusiness, UFRGS, Porto Alegre, Brazil 2Department of Forage and Agrometeorology, Faculty of Agricultural and Life Sciences, UFRGS, Porto Alegre, Brazil 3Department of Biophysics, Institute of Biosciences, UFRGS, Porto Alegre, Brazil *Corresponding author: Universidade Federal do Rio Grande do Sul, Centro de Estudos e Pesquisas em Agronegócios (CEPAN). Av. Bento Gonçalves, 7712 – Faculdade de Agronomia – 1º andar, Porto Alegre / RS / Brazil – zip code: 91.540-000. Tel. / fax: +55 51 3308 6586. E-mail address: milenedick@yahoo.com.br

Abstract:

Numerous mitigation strategies have been proposed in order to reduce environmental impacts from beef cattle production. In this sense, this study aimed to evaluate the effects of additive changes in the animal and pasture management of a beef cattle production system typical of south Brazil (baseline scenario – BS), in terms of climate change, land use and fossil depletion. These changes included: increasing the forage production; improving the forage quality; introducing legumes to replace nitrogen fertilization; improving the reproductive rates and; increasing the forage utilization efficiency. It was also considered the stabilization of the soil carbon (C) stocks in a long-term perspective. In BS was estimated, per kg of live weight gain, the greenhouse gas (GHG) emission of 22.5 kg of CO2 equivalents; the land use of 234.8 m2a and; 0.004 kg of oil equivalents in fossil depletion. Changes in forage production and quality resulted in GHG emissions equivalent to 7.8 – 20.7% of the BS and, to 0.5 – 1.2% of the BS with reproductive animal improvements. Land use reduces 9.4 – 30.6 times with these changes. The introduction of legumes to replace the nitrogen fertilizers engendered negative values of fossil depletion. The intensification of pasture utilization results in GHG emissions corresponding to 0.5% of the BS, and in a land use 32 times lower. Considering the long-term stabilization of soil C stocks, the systems that received nutritional and reproductive improvements presented reductions of GHG emissions from 2.5 – 3.2 times. A sensitivity analysis indicated the possibility of all short term improved scenarios become net sinks of C if gradual increments of root / shoot ratios in the range of values suggested by Intergovernmental Panel on Climate Change for Pampa Biome were applied. The scenarios confirm the hypothesis that productive improvements and environmental protection are not contradictory, and highlight the importance of biomass C dynamics and regional peculiarities in mitigation of environmental impacts from forage-livestock systems.

Key words: Global warming. Grassland restoration. LCA. Rotational grazing. Soil carbon stocks. Sustainable intensification.

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

2

1 Introduction

Environmental problems in recent decades have highlighted production issues related to pollution, environmental degradation and climate change. In this way environmental impacts of agricultural and food products are typically of high concern (Ridoutt et al. 2014). Annually, agriculture releases to the atmosphere significant amounts of CO2, CH4 and N2O (Audsley & Wilkinson, 2014; Nemecek & Kagi, 2007; Smith et al., 2008), whereas there is still uncertainty as to how food demand will evolve in the future (Garnett et al, 2013; Garnett, 2014; Thornton & Herrero (2014). Thus, authors such Beauchemin et al. (2011) and Bonesmo et al. (2013) postulate the urgency to establish practices to increase food production while minimizing its influence on climate change. In this new global context, knowledge of the production systems and environment relations has become an imminent need.

The importance of the Brazilian agribusiness placed the country in a prominent position regarding GHG emissions from agricultural sector. In the world, ruminants are responsible for 25% of methane production, whereas in Brazil this contribution can reach 70% (MCT, 2010). Thus, reductions in these emissions are fundamental, and conducting studies to elucidate the impacts of livestock on the environment, especially with regard to plant-animal dynamics (Blanco et al., 2007; Medeiros et al., 2007; Pedroso et al., 2004), taking into account local production characteristics, has become not only a necessity, but also an obligation.

Life cycle assessment (LCA) studies are suitable in this context, since they allow the entire system to be involved, including complex activities such as livestock (Beauchemin et al., 2011). This approach with simulations of herd has been used in different geographic regions and production systems to estimate the environmental impacts of ruminant production (Beauchemin et al., 2011; 2010; Casey & Holden, 2006; Ogino et al., 2007; Pelletier et al., 2010; Schader et al., 2014). In this work, LCA was used to evaluate different alternatives for mitigating the impacts of pastoral beef cattle production systems typical of southern Brazil, which according Ruviaro et al. (2012) are poorly studied despite their economic, social and environmental importance.

Many authors (Audsley & Wilkinson, 2014; Garnett, 2014; Gerber et al., 2013; Herrero et al., 2014) have highlighted the importance of the assumptions of sustainable intensification in agriculture, in order to minimize their impact and ensure food security. Increasing production efficiency, rationalizing the resource use, and reducing waste are crucial goals. In this sense, the study aimed to evaluate the influences of changes in the animal and pasture management of the traditional beef cattle production system of southern Brazil on the GHG balance, land use and the fossil fuels depletion. The short-term effects of the following practices were evaluated: improving the forage production throughout the year; increasing forage quality; substitution of nitrogen fertilization by the use of legumes; improving reproductive rates and; increasing the forage utilization efficiency. The stabilization of soil C stocks in the long term was also considered.

2 Methods

The LCA was described by the definitions of standards ISO14040 (2006) and ISO14044 (2006). The analysis was limited to environmental aspects, and did not take into account social and economic issues. The LCA was done in order to represent the environmental impacts of the entire cycle of beef cattle production and its components.

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

3

The impacts of mitigation practices on GHG emissions, land use, and fossil depletion were assessed relative to the baseline scenario (BS), which estimated farm based impacts from the extensive beef cattle production system of southern Brazil. The description was based on references with emphasis on data from representative farms. Further information may be obtained at Dick et al. (2014).

2.1 System boundary and functional unit

The southern Brazil has a cattle herd of 27.98 million head (IBGE, 2011), and more than half of these are found in Rio Grande do Sul State, particularly in the Pampa Biome (Fig. 1). The dominant vegetation is natural grassland with predominant Paspalum, Axonopus, Briza and Bromus species, sparse shrubs and trees. The frequent soil types are Mollisols, Vertisols and Ultisols, with limitations due to low natural fertility, acidity and susceptibility to erosion. The climate is humid subtropical with well-defined seasons, and allows the growth of tropical and temperate species (Gonzalez et al., 2009; Krolow et al., 2014; 2012) in the same area, resulting in a high potential for forage production and quality throughout the year. However, in the extensive production system the animals are conducted year-round on pastures grazed continuously with little or no subdivision and fertilization, and supplementation only with common salt. The forage and animal production rates are low, according to the MCT (2010), leading to an excessive permanence time of the animals in the system.

The scenarios proposed were obtained by the simulation of representative properties of this ecoregion and include the following: animals; native grassland and pastures improved by the introduction of grasses and leguminous; fertilization, liming, and mowing; supplementation (common and mineral salt); the resources used to produce these components (minerals, fuels, etc.); and the transport of different materials, both externally and internally, to the production unit (Fig. 2). Emissions associated with capital goods (machinery, buildings, etc.) and medicines were not considered due to their small impact (Cederberg et al., 2009). Characteristics of each scenario and differences between them are described in Table 1.

The herd evolution was obtained as recommended by IPCC (2006), tier 2, and composed of a herd originated from 100 females and four males weaned at an average age of six months, and their progeny during its productive life. The LCA began when the initial animals were weaning, continued through the meat production cycles, and ended when the initial cows and bulls were fully replaced (12 years) according to the availability for replacement animals in BS.

The functional unit (FU) was defined as 1 kg of live weight gain (LWG) at the farm-gate. For reference comparisons, the carcass weight was assumed to be 50% of the total live weight.

2.2 Inventory assessment

Resource inputs for and emissions from the use of pastures, the cultivation of forages, the manure handling, and the enteric fermentation by cattle were estimated. Equations and assumptions used for the estimation of emissions were summarized in table 2. Resource inputs for and emissions from fertilizer and supplementation production were taken from Nemecek & Kägi (2007). All transport operations, including transport of agricultural production inputs from a local storehouse to the farm, were assumed to be realized using either a truck 28t (Frischknecht et al., 2007), in an average distance of 0.25 tkm (tonne-kilometers). To all energy inputs for process, the Brazilian average electricity mix from Frischknecht et al. (2007) was used. Resource inputs for and emissions from the

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

4

internally mechanized operations were based on Jungbluth et al. (2007). With regard to the water supply to the animals, we considered natural water sources in the BS, and the use of water troughs in the other scenarios. In this case, the energy required for water distribution was added.

The GHG emissions for each scenario were estimated according to animal categories for the entire period (12 years) and per kg of LWG. The GHG included: the methane emissions (CH4), from enteric fermentation and excreta of animals; the direct and indirect nitrous oxide emissions (N2O) from the disposal of the excreta of grazing animals; and the carbon dioxide (CO2) balance.

The enteric CH4 emissions were calculated according to the IPCC (2006), tier 2. Daily net energy requirements for each category were estimated from energy expenditures for maintenance, activity, growth, pregnancy, lactation and work, as appropriate. The gross energy (GE) intake was estimated according the digestibility (IPCC, 2006), and the enteric CH4 emissions were calculated from GE intake using the specific CH4 conversion factors (Ym).

The methane emissions from manure were based on volatile solids production, according to IPCC (2006), taking into account the GE intake, the diet digestibility, the maximum CH4 producing capacity of the manure (Bo) and the CH4 conversion factor to the manure management practice used, considering the deposition of manure directly into the soil by animals.

The direct N2O emissions were estimated from the manure N, multiplied by a specific emission factor for the manure handling system (deposited on pasture). The manure N was calculated by difference into N intake and N retention of the animals based on IPCC (2006) and NRC (2000). Indirect N2O emissions from N lost from the farm via run-off, leaching and volatilization were also included. These emissions were estimated from the assumed fractions of N lost from manure, residues, and fertilizer, adjusted for climatic conditions as detailed by MCT (2010), and the IPCC (2006) emission factor. The biological N fixation was estimated at 100 kg N / ha / y (Rattray, 2005) and the N2O emissions were considered as suggested by IPCC (2006).

The estimated balance of soil carbon (C) assumed that areas managed similarly for long periods of time (decades) approached steady state of soil C storage where the liquid CO2 exchange is negligible. However, changes in land use or management can induce gains or losses of C in the soil. Biomass C gains and losses due to changes in land use were determined as proposed by IPCC (2006) by estimation the dry matter (DM) production changes due to the successive adoption of following practices to improve the pastures: fertilization; introduction of winter and summer grasses and legumes; improved pasture management. The C additions from shoots and roots were estimated as suggested by Bolinder et al. (1997) from which was subtracted the C exported and emitted by the animals (enteric fermentation and respiration) and soil. For this purpose, the root / shoot ratio and C content in MS proposed by the IPCC (2006), and the values of C in the carcass of beef cattle and CO2 derived from respiration of animals per day proposed by Byrne et al. (2007) was used. Finally, the conversion factors of the total C contained in the pasture, in the probable increase of soil C proposed by Santos et al (2011) were used to estimate the potential of soil C sequestration per year.

2.3 Impact assessment

Environmental impacts were estimated by using the Recipe midpoints method, version 1.06 with normalization world H, hierarchical perspective incorporated into the

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

5

SimaPro ® 7.3.3 software (Goedkoop et al, 2010; 2009). The different emissions were expressed in kg CO2 equivalent (kg CO2 eq.), based on their global warming potential in a time horizon of 100 years. The following parameters were considered for this conversion: kg CO2 x 1, kg N2O x 298 and kg CH4 fossil x 25 (Forster et al., 2007), and kg CH4 biogenic x 22 (Munöz et al, 2013; 2012). Land use and fossil fuel depletion were expressed in m2a and kg oil eq., respectively.

2.4 Description of mitigation strategies

The different mitigation strategies (Table 1) have been proposed to simulate the implementation of improvements in the BS in order to determine their short and long term effects on GHG emissions, land use, and fossil depletion.

2.4.1 Scenario 1 – Introduction of winter grasses in native pastures with nitrogen fertilization

The predominance of summer species in native pasture causes a seasonal reduction in herbage allowance and animal weight losses in autumn-winter. Thus, in scenario 1, the over seeding of winter grasses, nitrogen fertilization, and rotational grazing, with a weekly change of paddocks, were performed in order to promote a greater quantity and quality of forage, especially in the months considered most critical in the region. Increased biomass production of grassland due to change of land use resulted in a forecast increase of soil C stock.

2.4.2 Scenario 2 – Introduction of winter and summer grasses in native pastures with nitrogen fertilization

Because the native forage species tend to be less productive than improved varieties, high production tropical forages are used to increase the dry matter yield. In scenario 2, the over seeding of summer grasses were included in the practices that characterize the scenario 1. The proposal aims to increase the production and quality of forage in the summer months, resulting in a higher average daily gain. The increase in forage production originated a new forecast increase in soil C stock.

2.4.3 Scenarios 3 and 4 – Introduction of legumes to replace nitrogen fertilizers

The introduction of winter and summer legumes was examined in scenarios 3 and 4, replacing the application of nitrogenous fertilizers adopted in scenarios 1 and 2. The nitrogen contents derived, respectively, from fertilization and biological fixation, in scenarios 1 and 3 and in scenarios 2 and 4 were equivalent.

2.4.4 Scenarios 5 and 6 – Increments of weaning rate

Nutritional improvements generally result in increased reproductive rates. The effects of increased weaning rate under the conditions that characterize scenarios 3 and 4 (55% of weaning rate) were considered in scenarios 5 and 6 (78% and 85% of weaning rate, respectively).

2.4.5 Scenario 7 – Intensification of pasture utilization

The use of rotational grazing, with daily exchange of paddocks, was evaluated in this scenario as a way to optimize land use and enhance quality and forage utilization efficiency characteristics of scenario 6.

2.4.6 Scenarios 8 to 10 – Stabilization of carbon stocks over time

The proposition of scenarios 8 – 10 aims to add to the mitigation alternatives a perspective of long term. Thus, stabilization of C stocks in soil after 20 years of gradual

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

6

increase, which happens to the attainment of the equilibrium characteristic of the new land use, was simulated from scenarios 5 – 7.

2.5 Sensitivity analysis

Although our scenarios according to the precautionary principle assumed a minimal root / shoot ratio in the range of values suggested by IPCC (2006) for the Pampa Biome (1,6 for subtropical grasslands to 4,0 for steppes), we conducted a sensitivity analysis to test the potential impact of gradual increments of this ratio on estimated C balance of the short term scenarios.

In reality, though a large proportion of plant growth is allocated to below ground (Stanton, 1988) their amount is one of the most poorly understood attributes of grasslands. The methodological limitations issues associated with root biomass and grazing effects (Hart, 2001; Olsen et al., 2011; Pucheta et al., 2004; Reeder & Schuman, 2002) quantification remains a critical source of uncertainty.

3 Results and discussion

The LCA results of the beef cattle production systems are presented in table and figure 3.

3.1 Baseline scenario

The BS showed a GHG emission of 22.5 kg CO2 eq. / kg LWG, with 84.6% produced by animals, 15.4% from native pasture and 0.01% regarding the mineral supplementation (common salt). With respect to land use and fossil fuel depletion, the system uses 234.8 m2a and 0.004 kg oil eq. to produce 1 kg LWG, respectively.

In kg of hot carcass (HSCW), these emissions (45 kg CO2 / kg HSCW) are similar to those obtained by Weiss & Leip (2012) for livestock systems in Cyprus and Latvia (up to 40 kg CO2 eq. / kg HSCW). The values reported by these authors in Austria and in the Netherlands (14.2 and 17.4 kg CO2 eq. / kg HSCW, respectively), highlight the differences between GHG emissions from intensive production systems – typical of developed countries (Nguyen et al., 2009; Stackhouse-Lawson, 2012), where higher yields exert a diluting effect of total emissions – and from extensive systems found in other countries.

3.2 Mitigation strategies

The application of improved practices resulted in different ways to reduce GHG emissions, land use, and fossil depletion, reiterating the importance of productive improvements to mitigate environmental impacts (Capper et al., 2009; Gerber et al., 2011), according to the challenge of sustainable intensification: producing more total nutrients with environmental benefits (Audsley & Wilkinson, 2014; Garnett et al., 2013).

The introduction of winter grasses in native pastures with nitrogen fertilization (scenario 1) resulted in a reduction of GHG emissions of 4.8 times compared to BS. This difference was due to the shorter permanence time of animals in the system and production increase that made possible the reduction of its GHG emissions per kg LWG (10 kg CO2 eq. / kg LWG). Increased pasture quality contributed to this reduction. Moreover, the increase in forage production, featuring a change of land use, resulted in a negative value of GHG emissions by pasture (-5.4 kg CO2 eq. / kg LWG) which offset part of the total emissions. These values corroborate the importance of reporting the emissions from the land use change, because this emissions source can drastically affect GHG emissions (Flysjö et al. 2012; Guerci et al., 2014). Mineral supplementation in the form of mineral

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

7

salt and water supply in troughs resulted in a small increase in emissions (0.017 to 0.09 kg CO2 eq. / kg LWG). The land use was 10.7% of BS, whereas the fossil depletion was 137 times greater.

The forage improvement from the introduction of summer grasses (scenario 2) resulted in a reduction of GHG emissions of 7.1 times compared to BS. This represents 68.1% of the GHG emissions of scenario 1 and results from the improvement of forage production and reducing the permanence time of animals in the system. The land use was 24.7 times lower and fossil depletion was 113 times greater than at BS.

The increases observed in scenarios 1 and 2 in the supply, quality and distribution of forage throughout the year and in the forage utilization efficiency due to the adoption of rotational grazing with a weekly exchange of paddocks, impacted heavily on the production parameters. As demonstrated in several studies, (Beauchemin et al., 2011; Dollé et al., 2011; Schader et al., 2014; Soussana et al., 2010) the environmental impacts of the production system decreased with the concomitant change of the defining parameters of GHG emissions by animals and the contribution of the pasture, which constitute in a sink of C, with the change of land use.

The large variation in the systems is an advantage for the reduction land requirements for meat production (Elferink & Nonhebel, 2007). As noted by Bartl et al. (2011) in Peru, productive improvements represent important opportunities for reducing land use. Furthermore, according to Cederberg et al. (2009), such improvements can reduce local pressures involving land disputes, allowing to stop or even reverse the expansion of production in ecosystems where there is clear interest in maintaining its natural state. Maintaining less productive systems can generate local benefits, however, it is essential to consider potential indirect consequences, in particular the risk that land is cleared for agricultural production elsewhere to compensate for locally lower yields (Garnett et al., 2013).

The introduction of legumes to replace the use of nitrogen fertilizers (scenarios 3 and 4) resulted in reductions of GHG emissions of 11.8 and 12.5 times compared to BS. Emissions in scenarios 3 and 4 represent 40.4 and 56.3% of those obtained in scenarios 1 and 2, respectively, demonstrating the advantage of using legumes. Those reductions are due to the improved quality of the pasture related to lower GHG emissions by animals, and to the suppression of nitrogen fertilizer use associated with lower use of fossil fuels (-0.125 and -0.061 kg oil eq. / kg LWG in 3 and 4 scenarios, respectively) indicated by Piorr (2003) and Yan et al. (2013) as a key measure of GHG mitigation. As regards the land use, the values obtained for the 3 and 4 scenarios were 8.9 and 3.3% of the BS, respectively. When compared to scenarios 1 and 2, these values correspond to 83.7 and 81.1%, respectively.

Improving reproductive performance, characterized in scenarios 5 and 6, resulted in GHG emissions equivalent to 1.3 and 0.5% of the BS. In response to this increase in productivity, the values were 15.8 and 6.7% of those observed in scenarios 3 and 4, respectively. This was due to the dilution effect of emissions by a greater amount of product observed despite the increase observed in the total number of animals and therefore in the total emissions (Table 4).

Improving the forage utilization efficiency by using rotational grazing with daily exchange of paddocks (scenario 7) resulted in GHG emissions corresponding to 0.5% of the BS. The land use decreased to 3.1% and 94.8% of the values obtained in the BS and S6, respectively. These values are related to reductions of the senescence rate, and forage losses for animal trampling, which motivates increases in the forage quality and production

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

8

(MCT, 2010). Maintaining adequate levels of ground cover and herbage allowance is essential to avoid loss of biodiversity and nutrients.

With the stabilization of the soil C stocks, which tends to occur in areas with the same production management after long periods (IPCC, 2006), there is an increase in GHG emissions compared to scenarios 5, 6 and 7 (by suppression of C sequestration previously computed). Even so, the values in scenarios 8, 9 and 10, respectively were 2.5, 3.0 and 3.2 times lower than GHG emissions at BS. This fact emphasizes the importance of the improved practices use in the current context of climate change. According to O'Hara et al. (2003), CH4 emissions are lower, as the animals are more productive. Furthermore, plant production increment generate increases in soil C stocks (Conant et al., 2001; Paustian et al., 1997), which under certain conditions can achieve the same or even higher levels than those found in native forests (Moraes et al., 1995; Neill et al., 1997). These facts should be considered to encourage the adoption of these practices as a strategic way of obtaining productive and environmental advantages, especially with regard to pastoral livestock production systems. However, the implementation of alternative practices should consider the local socioeconomic and environmental conditions and geographic restrictions (Herrero et al., 2014; Schader et al., 2014). Thus, the viability of these productive increments does not mean yields should increase everywhere or at any cost.

3.3 Sensitivity analysis

In forage species root to shoot ratios are negatively related to mean annual temperature (Mokany et al. 2006) and the grazing effects can increase and even double the total root biomass (Pucheta et al. 2004). This increase may be higher in intensive grazing (Reeder & Schuman, 2002), since their management is adequate. This impact can be still greater if the grazing influences on vegetation dynamics (selection of perennials with more fibrous and deep roots at the expense of annual plants) and their renewal rates (Hart, 2001; Olsen et al. 2011) are considered.

In this work, gradual increments of root to shoot ratio in the range of values suggested by IPCC (2006) for Pampa Biome more than offset the GHG emissions from all short term scenarios (Table 5). If root / shoot ratios of 2.9 for scenarios using nitrogen fertilizers (1 and 2), 2.3 for scenarios using legumes (3 and 4) and 1.7 for scenarios with reproductive improvements (5 to 7) were adopted, respectively, these net emitters simulated beef production systems become net C sinks. Average GHG emissions were -0.4, -2.3 and -3.7 kg CO2 eq. / kg LWG for scenarios using nitrogen fertilizers, legumes and reproductive improvements, respectively, when root / shoot ratio of 2.9 was used.

4 Conclusions and recommendations

The use of improved practices in beef cattle traditional system of southern Brazil has positive impacts regarding the GHG emissions, land use, and fossil fuel depletion per kg LWG. However, the historical knowledge and consideration of the entire production system are fundamental to its definition.

Different production practices allow modifications of environmental impacts in the short term: (1) the introduction of winter and summer grasses and the use of rotational grazing, with a weekly exchange of paddocks, substantially reduce GHG emissions and land use due to increases in pasture production and quality, and increase the fossil depletion; (2) the introduction of legumes to replace nitrogen fertilizers results in further reductions of GHG emissions and land use, related to increases in pasture quality, and reduces the use of fossil fuels; (3) similarly, increasing weaning rates contributes to the

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

9

reduction of GHG emissions, showing that improvements in reproductive management also contribute to mitigating the environmental impacts of livestock production systems; (4) using rotational grazing with daily exchange of paddocks, further contributes to the reduction of GHG emissions and land use by improving pasture quality, and reducing senescence rate and losses by animal trampling.

In the long term, after stabilization of soil C stocks, the GHG emissions of improved systems remain significantly lower compared to BS, even with the suppression of the statement of atmospheric C removals, occurring in first 20 years after the improvements implementation.

All improved short term scenarios become net sinks of C when estimates are made from intermediate values of root / shoot ratios in the range suggested by IPCC (2006) for the Pampa Biome.

The scenarios demonstrate different possibilities of mitigating the environmental impacts from beef cattle production in southern Brazil. Moreover, the diversity of the results provides information for a better understanding of regional singularities necessary to propose productive alternatives. However, improvements should be addressed by comprehensive LCA studies to ensure that the transition to an alternative practice does not create other socio-economic and environmental problems.

The uncertainties of root quantification, and grazing effects on the dynamics of pastures and soil C stocks stimulate specific studies. Moreover, the environmental impacts observed when we considered the stabilization of soil C stocks confirm the hypothesis that productive improvements and environmental protection are not contradictory and that the environment must be considered as a partner to work together. Finally, the uncertainty of estimates, due to the partial use of secondary data produced in other geographical and productive situations, highlights the need of undertaking work aimed at proposing regional parameters in order to maximize their contribution.

Acknowledgments

The financial support of CAPES (Coordination for Enhancement of Higher Education Personnel) is gratefully acknowledged.

References

Audsley, E., Wilkinson, M., 2014. What is the potential for reducing national greenhouse gas emissions from crop and livestock production systems? J. Clean. Prod. 73, 263-268.

Bartl, K., Gómez, C.A., Nemecek, T., 2011. Life cycle assessment of milk produced in two smallholder dairy systems in the highlands and the coast of Peru. J. Clean. Prod. 19 (13), 1494-1505.

Beauchemin, K.A., Janzen, H.H., Little, S.M., McAllister, T.A., McGinn, S.M., 2010. Life cycle assessment of greenhouse gas emissions from beef production in western Canada: a case study. Agric. Syst. 103 (6), 371-379.

Beauchemin, K.A., Janzen, H.H., Little, S.M., McAllister, T.A., McGinn, S.M., 2011. Mitigation of greenhouse gas emissions from beef production in western Canada – evaluation using farm-based life cycle assessment. Anim. Feed Sci. Technol. 166-167, 663-677.

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

10

Blanco, C., Sosinski, E., Santos, B., Abreu da Silva, M., Pillar, V.P., 2007. On the overlap between effect and response plant functional types linked to grazing. Commun. Ecol. 8 (1), 57-65.

Bolinder, M.A., Angers, D.A., Dubuc, J.P., 1997. Estimating shoot to root ratios and annual carbon inputs in soils for cereal crops. Agric. Ecosyst. Environ. 63, 61-66.

Bonesmo, H., Beauchemin, K.A, Harstad, O.M., Skjelva, A.O., 2013. Greenhouse gas emission intensities of grass silage based dairy and beef production: A systems analysis of Norwegian farms. Liv. Sci. 152, 239-252.

Byrne, K.A., Kiely, G., Leahy, P., 2007. Carbon sequestration determined using farm scale carbon balance and eddy covariance, Agric. Ecosyst. & Environ. 121 (4), 357-364.

Capper, J.L., Cady, R.A., Bauman, D.E., 2009. The environmental impact of dairy production: 1944 compared with 2007. J. Anim. Sci. 2160-2167.

Casey, J.W., Holden, N.M., 2006. Quantification of GHG emissions from sucker-beef production in Ireland. Agric. Syst. 90 (1-3), 79-98.

Cederberg, C., Meyer, D., Flysjö, A., 2009. Life cycle inventory of greenhouse gas emissions and use of land and energy in Brazilian beef production. SIK-report. SIK e Institutet för livsmedel och bioteknik.

Conant R.T., Paustian K., Elliott E.T., 2001. Grassland management and conversion into grassland effects on soil carbon. Ecol. Applic. 11 (2), 343–355.

Corrêa, E.S., 2001. Desempenho reprodutivo em um sistema de produção de gado de corte. Embrapa Gado de Corte.

Dollé, J.B., Agabriel, J., Peyraud, J.L., Faverdin, P., Manneville, V., Raison, C., Gac, A., Le Gall, A., 2011. Les gaz à effet de serre en élevage bovin: évaluation et leviers d’action. Prod. Anim. 24 (5), 415.

Dick, M., Abreu da Silva, M., Dewes, H., 2014. Life cycle assessment of beef cattle production in two typical grassland systems of southern Brazil. J. Clean. Prod. http://dx.doi.org/10.1016/j.jclepro.2014.01.080.

Elferink, E.V., Nonhebel, S., 2007. Variations in land requirements for meat production. J. Clean. Prod. 15 (18), 1778-1786.

Euclides Filho, K., 2000. Produção de bovinos de corte e o trinômio genótipo ambiente- mercado. Embrapa Gado de Corte.

Flysjö, A., Cederberg, C., Henriksson, M., Ledgard, S., 2012. The interaction between milk and beef production and emissions from land use change e critical considerations in life cycle assessment and carbon footprint studies of milk. J. Clean. Prod. 28, 134-142.

Forster, P., Ramaswamy, V., Artaxo, P., Berntsen, T., Betts, R., Fahey, D.W., Haywood, J., Lean, J., Lowe, D.C., Myhre, G., Nganga, J., Prinn, R., Raga, G., Schulz M., Van Dorland, R. 2007: Changes in Atmospheric Constituents and in Radiative Forcing. In: Solomon et al. (eds.), Climate Change 2007: The Physical Science Basis. Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press.

Frischknecht, R., Tuchschmid, M., Faist Emmenegger, M., Bauer, C., Dones, R., 2007. Strommix und Stromnetz. ecoinvent report No. 6 data v2.0. Swiss Centre for Life Cycle Inventories.

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

11

Garnett, T. 2014. Three perspectives on sustainable food security: efficiency, demand restraint, food system transformation. What role for life cycle assessment? J. Clean. Prod. 73, 10-18.

Garnett, T., Appleby, M.C., Balmford, A., Bateman, I.J., Benton, T.G., Bloomer, P., Burlingame, B., Dawkins, M., Dolan, L., Fraser, D., Herrero, M., Hoffmann, I., Smith, P., Thornton, P.K., Toulmin, C., Vermeulen, S.J., Godfray H.C.J., 2013. Sustainable Intensification in Agriculture: Premises and Policies. Science. 341, 33-34.

Gerber, P., Vellinga, T., Opio, C., Steinfeld, H., 2011. Productivity gains and greenhouse gas emissions intensity in dairy systems. J. Liv. Sci. 139, 100-108.

Gerber, P.J., Steinfeld, H., Henderson, B., Mottet, A., Opio, C., Dijkman, J., Falcucci, A., Tempio, G., 2013. Tackling climate change through livestock – A global assessment of emissions and mitigation opportunities. FAO, Rome.

Goedkoop, M., Heijungs, R., Huijbregts, M., Schryver, A.D., Struijs, J., Van Zelm, R., 2009. ReCiPe 2008: a life cycle impact assessment method which comprises harmonised category indicators at the midpoint and the endpoint level. In: VROMeRuimte en Milieu, Ministerie van Volkshuisvesting, Ruimtelijke Ordening en Milieubeheer.

Goedkoop, M., Schryver, A.D., Oele, M., Durksz, S., de Roest, D., 2010. Introduction to LCA with SimaPro 7. Pré Consultants.

Gonzalez, H.L., Velho, I.M.P.H., Abreu da Silva, M., Medeiros, R.B., Paim, N.R., Nörnberg, J.L., 2009. Milk quality of Jersey cows kept on winter pasture supplemented or not with concentrate. Braz. J. Anim. Sci. 38 (10), 1983-1988.

Guerci, M., Bava, L., Zucali, M., Tamburini, A., Sandrucci, A., 2014. Effect of summer grazing on carbon footprint of milk in Italian Alps: a sensitivity approach. J. Clean. Prod.73. 236-244.

Hart, R.H. 2001. Plant biodiversity on short grass steppe after 55 years of zero, light, moderate, or heavy cattle grazing. Plant Ecol. 155, 111–118.

Herrero, M., Thornton, P.K., Bernués, A., Baltenweck, I., Vervoort, J., Steeg, J., Makokha, S., Wijk, M.T., Karanja, S., Rufino, M.C., Staal, S.J., 2014. Exploring future changes in smallholder farming systems by linking socio-economic scenarios with regional and household models. Global Environ. Change. 24, 165-182.

IBGE, 2011. Produção da Pecuária Municipal, Rio de Janeiro, p.65.

IPCC, 2006. IPCC Guidelines for National Greenhouse Gas Inventories, Volume 4: Agriculture, Forestry and Other Land Use. Intergovernmental Panel on Climate Change. Eggleston H.S., Buendia L., Miwa K., Ngara T. and Tanabe K. (eds). IGES, Japan.

ISO14040, 2006. 14040 Environmental Management-life Cycle Assessment principles and Framework. International Organization for Standardization.

ISO14044, 2006. 14044: Environmental Managementd life Cycle assessment requirements and Guidelines. International Organization for Standardization.

Jungbluth, N., Chudacoff, M., Dauriat, A., Dinkel, F., Doka, G., Faist Emmenegger, M., Gnansounou, E., Kljun, N., Schleiss, K., Spielmann, M., Stettler, C., Sutter, J., 2007. Life Cycle Inventories of Bioenergy. ecoinvent report No. 17. Swiss Centre for LCI.

Kichel, A.N., Costa, J.A.A., Verzignassi, J.R., Queiroz, H.P., 2011. Diagnóstico para o planejamento da propriedade. Embrapa Gado de Corte, p.182.

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

12

Krolow, R.H., Abreu da Silva, M., Paim, N.R., Medeiros, R.B., Gonzalez, H.L., 2012. Milk composition of Holstein cows grazing ryegrass with the use of white clover as a protein source. Braz. J. Veterinary Anim. Sci. 64 (5), 1352-1359.

Krolow, R.H., Abreu da Silva, M., Paim, N.R., Medeiros, R.B., Velho, I.M.P.H., 2014. Ingestive behavior of dairy cows in annual ryegrass pasture, fed with different proteic sources. Braz. J. Veterinary Anim. Sci. 66(3), 845-852.

Lalman, D., Doye, D., 2005. Beef Cattle Manual. Oklahoma State University.

Maraschin, G.E., 2001. Production potential of South America grasslands. In: Proceedings of the XIX International Grassland Congress: Grassland Ecosystems: an Outlook into the 21st Century, 5-15.

MCT, 2010. Anthropogenic Emissions and Removals Inventory of Greenhouse Gases Not Controlled by the Montreal Protocol e Initial Communication from Brazil. Part II. Ministry of Science and Technology, Brasília.

Medeiros, R.B., Pedroso, C.E.S., Jornada, J.B.J., Abreu da Silva, M., Saibro, J.C., 2007. Diurnal ingestive behavior of sheep grazing annual ryegrass at different phenological growth stages. Braz. J. Anim. Sci. 36 (1), 198-04.

Mokany, K., Raison, R.J., Prokushkin, A.S., 2006. Critical analysis of root: shoot ratios in terrestrial biomes. Glob. Change Biol. 12 (1), 84–96.

Moraes, J.L., Cerri, C.C., Melillo, J.M., Kicklighter, D., Neil, C., Steudler, P.A., Skole, D.L., 1995. Soil carbon stocks of the Brazilian Amazon basin. Soil Sci. Soc. Am. J. 59 (1), 244-247.

Muñoz, I., Rigarlsford, G., Canals, L.M., King, H., 2012. Accounting for greenhouse-gas emissions in LCA from the degradation of chemicals in the environment. In: 6th SETAC World Congress / SETAC Europe 22nd Annual Meeting.

Muñoz, I., Rigarlsford, G., Canals, L.M., King, H., 2013. Accounting for greenhouse gas emissions from the degradation of chemicals in the environment. Int. J. Life Cycle Assess. 18, 252-262.

Neill, C., Melillo, J.M., Steudler, P.A., Cerri, C.C., Moraes, J.L., Piccolo, M.C., Brito, M., 1997. Soil carbon and nitrogen stocks following forest clearing for pasture in the Southwestern Brazilian Amazon. Ecol. Applic. 7, 1216–1225.

Nemecek, T., Kägi, T., 2007. Life cycle inventories of agricultural production systems. final report ecoinvent v2.0 No. 15. Agro scope Reckenholz-Taenikon Research Station ART, Swiss Centre for Life Cycle Inventories.

Nguyen, T.L.T., Hermansen, J.E., Mogensen, L., 2010. Environmental consequences of different beef production systems in the EU. J. Clean. Prod. 18 (8), 756-766.

NRC, 2000. Nutrient Requirements of Beef Cattle E-974. Department of Animal Science, Oklahoma.

Nunes, I.J., 1998. Nutrição animal básica, FCP-MVZ Ed., Belo Horizonte.

Ogino, A., Orito, H., Shimada, K., Hirooka, H., 2007. Evaluating environmental impacts of the Japanese beef cow e calf system by the life cycle assessment method. Anim. Sci. J. 78 (4), 424-432.

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

13

O'Hara, P., Freney, J., Uliatt, M., 2003. Abatement of agricultural non-carbon dioxide greenhouse gas emissions: a study of research requirements. Ministerial Group on Climate Change. New Zealand. p.170.

Oliveira, R.L., Barbosa, M.A.A.F., Ladeira, M.M., Silva, M.M.P., Ziviani, A.C., Bagaldo, A.R., 2006. Beef cattle nutrition and production during reproduction phase. Braz. J. Anim. Health Prod. 7 (1), 57-86.

Olsen, Y.S., Dausse, A., Garbutt, A., Ford, H., Thomas, D.N., Jones, D.L., 2011. Cattle grazing drives nitrogen and carbon cycling in a temperate salt marsh. Soil Biol. & Biochemistry. 43, 531-541.

Paustian, K., Andren O., Janzen H.H., Lal, R., Smith, P., Tian, G., Tiessen, H., Van Noordwijk, M., Woomer, P.L., 1997. Agricultural soils as a sink to mitigate CO2 emissions. Soil Use and Manag. 13, 230–244.

Pedroso, C.E.S., Medeiros, R.B., Abreu da Silva, M., Jornada, J.B.J., Saibro, J.C., Teixeira, J.R.F., 2004. Sheep behavior at the pregnancy and at the lactation grazing on different phenological stages of annual ryegrass. Braz. J. Anim. Sci. 33 (3), 1340-1344.

Pelletier N., Pirog R., Rasmussen R., 2010. Comparative life cycle environmental impacts of three beef production strategies in the Upper Midwestern United States. Agr. Syst., 103 (6), 380-389.

Pillar, V., Tornquist, C.G., Bayer, C., 2012. The southern Brazilian grassland biome: soil carbon stocks, fluxes of greenhouse gases and some options for mitigation. Braz. J. Biol. 72, 673-681.

Piorr, H.P., 2003. Environmental policy, agri-environmental indicators and landscape indicators. Agric., Ecosyst. & Environ. 98, 17–33.

Pucheta, E., Bonamici, I., Cabido, M., Díaz, S., 2004. Below-ground biomass and productivity of a grazed site and a neighbouring ungrazed exclosure in a grassland in central Argentina. Austral Ecol. 29, 201–208.

Rattray, P.V., 2005. Clover management, research, development and extension in the New Zealand pastoral industries. Commissioned by the Sustainable Farming Fund, p.218.

Reeder, J.D.; Schuman, G.E., 2002. Influence of livestock grazing on C sequestration in semi-arid mixedgrass and short-grass rangelands. Environ. Pollution. 116, 457–463.

Ridoutt, B.G., Page G., Opie K., Huang J., Bellotti W., 2014. Carbon, water and land use footprints of beef cattle production systems in southern Australia. J. Clean. Prod. 73, 24-30.

Ruviaro, C.F., Gianezini, M., Brandão, F.S., Winck, C.A., Dewes, H., 2012. Life cycle assessment in Brazilian agriculture facing worldwide trends. J. Clean. Prod. 28, 9-24.

Santos, B.R.C., Abreu da Silva, M., Medeiros, R.B., 2006. Interaction between grazing behavior and functional type dynamics in native grassland in the central depression region of Rio Grande do Sul. Braz. J. Anim. Sci. 35 (5), 1897-1906.

Santos, N.Z., Dieckow, J., Bayer, C., Molin, R., Favaretto, N., Pauletti, V., Piva, J.T., 2011. Forages, cover crops and related shoot and root additions in no-till rotations to C sequestration in a subtropical Ferralsol. Soil Till. Res. 111 (2), 208-218.

Schader, C., Jud, K., Meier, M.S., Kuhn, T., Oehen, B., Gattinter, A., 2014. Quantification of the effectiveness of greenhouse gas mitigation measures in Swiss organic milk production using a life cycle assessment approach. J. Clean. Prod. 73, 227-235

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

14

Scholl, J.M., Lobato, J.F.P., Barreto, I.L., 1976. Improvement of pastures by direct seeding into native grass in southern Brazil with oats and with nitrogen supplied by fertilize or arrow leaf clover. Turrialba. 26 (2), 144-149.

Siqueira, O.J.F., Scherer, E.E., Tassinari, G., Anghinoni, I., Patella, J.F., Tedesco, M.J., Milan, P.A., Ernani, P.R., 1987. Recomendações de adubação e calagem para os estados do Rio Grande do Sul e Santa Catarina. EMBRAPA-CNPT.

Smith, P., Martino, D., Cai, Z., Gwary, D., Janzen, H., Kumar, P., McCarl, B., Ogle, S., O’Mara, F., Rice, C., Scholes, B., Sirotenko, O., Howden, M., McAllister, T., Pan, G., Romanenkov, V., Schneider, U., Towprayoon, S., Wattenbach, M., Smith, J., 2008. Greenhouse gas mitigation in agriculture. Philosophical Transactions of the Royal Society B. Biol. Sci. 363, 789–813.

Soussana, J.F., Tallec, T., Blanfort, B., 2010. Mitigating the greenhouse gas balance of ruminant production systems through carbon sequestration of grasslands. Animal 4 (3), 334–350.

Stackhouse-Lawson, K.R., Rotz, C.A., Oltjen, J.W., Mitloehner, F.M., 2012. Carbon footprint and ammonia emissions of California beef production systems. J. Anim. Sci. 90 (12), 4641-4655.

Stanton, N.L., 1988. The underground in grasslands. Ann. Rev. Ecol. Syst. 19, 573–589.

Teixeira, J.R.F., Abreu da Silva, M., 2007. Typology of beef cattle production systems related to ectoparasitosis frequency. Braz. J. Anim. Sci. 36 (6), 2176-2183.

Thornton, P.K., Herrero, M., 2014. Climate change adaptation in mixed crop–livestock systems in developing countries. Glob. Food Secur. 3 (2), 99-107.

Weiss, F., Leip, A., 2012. Greenhouse gas emissions from the EU livestock sector: a life cycle assessment carried out with the CAPRI model. Agric. Ecosyst. Environ. 149, 124-134.

Yan, M.J., Humphreys, J., Holden, N.M., 2013. The carbon footprint of pasture based milk production: can white clover make a difference? J. Dairy Sci. 96 (2), 857-865.

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

Table 1 – Description of the scenarios. BS S1 S2 S3 S4 S5 S6 S7 S8 S9 S10

Herd structure

Weaned calves weight (kg) 2, 3, 11 170 210 230 210 230 210 230 230 210 230 230

Weaned heifers weight (kg) 2, 3, 11 150 190 210 190 210 190 210 210 190 210 210

Replacement rate (% / y) 2, 3 20 12.5 11.1 12.5 11.1 12.5 11.1 11.1 12.5 11.1 11.1

Weaning rate (%) 3 55 55 55 55 55 78 85 85 78 85 85

Mortality rate (%) 2, 3 4 4 4 4 4 1 1 1 1 1 1

Male-female ratio 1:1 1:1 1:1 1:1 1:1 1:1 1:1 1:1 1:1 1:1 1:1

Weight gain first year (kg / d) 5 0.1 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2

Weight gain (kg/d) 3, 5 0.23 0.5 0.8 0.6 1 0.6 1 1 0.6 1 1

First calving (months) 2, 3, 5 48 30 24 30 24 30 24 24 30 24 24

Milk production (l / head / d) 3 1.1 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2

Slaughter weight – males (kg) 5, 8 440 480 500 500 500 500 500 500 500 500 500

Slaughter weight – females (kg) 5, 8 420 460 480 480 480 480 480 480 480 480 480

Body weight, bulls (kg) 5, 8 600 700 700 700 700 700 700 700 700 700 700

Body weight, cows (kg) 5, 8 380 400 400 400 400 400 400 400 400 400 400

Forage intake (kg DM / head / d) 9 8.1 10 11.7 10 11.7 10 11.7 11.7 10 11.7 11.7

Water consumption (l / head / d) 10 50 50 50 50 50 50 50 50 50 50 50

Common salt consumption (g/ head/d) 6 50 - - - - - - - - - -

Mineral salt consumption (g / head /d) 6 - 150 150 150 150 150 150 150 150 150 150

Manure handling OP OP OP OP OP OP OP OP OP OP OP

Grassland composition

Pasture type 1, 12, 15 N W S WL SL WL SL SL WL SL SL

Production (t DM / ha / y) 7, 14 3 11.5 23 11.5 23 11.5 23 23 11.5 23 23

Digestibility energy (% DM) 8 47 52 60 55 64 55 64 67 55 64 67

Crude Protein (% DM) 8 12 13 14 15 17 15 17 17 15 17 17

Ym factor (% GE intake) 4 7.2 6.7 6.4 6.5 6.2 6.5 6.2 6 6.5 6.2 6

Forage utilization efficiency (%) 7 50 70 70 70 70 70 70 80 70 70 80

Root / shoot ratio 4 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6

Phosphorus fertilization (kgP2O5 / ha / y) 13 - 50 100 50 100 50 100 100 50 100 100

Potassium fertilization (kg K2O / ha / y) 13 - 65 130 65 130 65 130 130 65 130 130

Liming (t / ha / 3y) 13 - 1 2 1 2 1 2 2 1 2 2

Mowing / y 16 - 1 2 1 2 1 2 2 1 2 2

Overseed / y 16 - 0.5 1 0.5 1 0.5 1 1 0.5 1 1

Urea (kg / y) 16 - 100 200 - - - - - - - -

Seed winter grass (kg / y) 16 - 20 40 20 40 20 40 40 20 40 40

Seed winter leguminous (kg / y) 16 - - - 10 10 10 10 10 10 10 10

Seed summer grass (kg / y) 16 - - 40 - 40 - 40 40 - 40 40

Seed summer leguminous (kg / y) 16 - - - - 40 - 40 40 - 40 40

d = day; DM = dry matter; GE = gross energy; N = native pasture; OP = on pasture; S = native pasture with winter and summer grasses introduction; SL = native pasture with winter and summer grasses and leguminous introduction; W = native pasture with winter grasses introduction; WL = native pasture with winter grasses and leguminous introduction; y = year. 1Blanco et al. (2007); 2Corrêa (2001); 3Euclides Filho (2000); 4IPCC (2006); 5Kichel et al. (2011); 6Lalman & Doye (2005); 7Maraschin (2001); 8MCT (2010); 9NRC (2000); 10Nunes (1998); 11Oliveira et al. (2006); 12Santos et al. (2006); 13Siqueira et al. (1987); 14Scholl et al. (1976); 15Teixeira & Abreu da Silva (2007); 16Expert opinion.

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPTTable 2 – Assumptions used for the emissions/removals estimation.

Source Equation / emission / removal factor Methane a

Enteric fermentation Based on gross energy requirements and digestible energy in feed Ca = 0.36 Manure 0.01 kg CH4 (kg CH4)

-1 Bo = 0.13 m3 CH4 (kg)-1

Direct nitrous oxide a Manure 0.02 kg N2O-N (kg N)-1 N fertilizer b 0.0125 kg N2O-N (kg N)-1

Indirect nitrous oxide Manure a Volatilization 0.01 kg N2O–N (kg N)-1 Fracvolatilization = 0.2 kg N (kg N)-1 Leaching 0.0075 kg N2O-N (kg N)-1 Fracleach – 0.3 kg N (kg N)-1 N fertilizer Volatilization 0.01 kg N2O-N (kg N)-1b Fracvolatilization = 0.15 kg N (kg N)-1a Leaching 0.025 kg N2O-N (kg N)-1b Fracleach – 0.3 kg N (kg N)-1a

Carbon dioxide Liming a Dolomite 0.13 kg CO2-C (kg CaMg(CO3)2)-1 N fertilizer b 1.57 kg CO2 (kg CO(NH2)2)-1 Land use change 0.453 kg C (kg MS)-1 a 1.6 kg roots (kg shoots)-1 a 0.103 and 0.118 kg C sequestered annually in the 0–30 cm layer by

N fertilizer and legume introduction scenarios, respectively (kg C annual addition by pasture shoots and roots)-1 c

0.05 kg C exported (kg animal carcass)-1 d 5 kg CO2 (animal*day)-1 d Bo = methane producing capacity by manure produced relative to Latin America; Fracvolatilization = volatilization fraction; Fracleach = leaching fraction. aIPCC (2006). bNemecek & Kägi, 2007. cSantos et al. (2011). dByrne et al. (2007).

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPTTable 3 – Climate change, land occupation and fossil depletion for different scenarios, in kg CO2 eq., m2a and kg oil eq. (kg LWG)-1, respectively.

Climate Change

Land

Occupation

Fossil Depletion

Total Pasture Water Salt Animal

removal emission

BS 22.5 - 3.46 - 0.012 19.05 234.8 0.004 S1 4.7 -9.32 3.88 0.09 0.017 10.00 25.1 0.577 S2 3.2 -8.05 2.97 0.06 0.010 8.17 9.5 0.455 S3 1.9 -8.90 2.58 0.08 0.014 8.75 21 -0.125 S4 1.8 -7.37 1.94 0.05 0.008 7.60 7.7 -0.061 S5 0.26 -8.90 2.58 0.08 0.014 7.16 21 -0.125 S6 0.12 -7.37 1.94 0.05 0.008 5.98 7.7 -0.061 S7 0.11 -7.00 1.84 0.05 0.008 5.67 7.3 -0.058 S8 9.2 -0.67 2.58 0.08 0.014 7.16 21 -0.125 S9 7.5 -0.47 1.94 0.05 0.008 5.98 7.7 -0.061 S10 7.1 -0.45 1.84 0.05 0.008 5.67 7.3 -0.058

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPTTable 4 – Total live weight gain and emissions from animals in different scenarios.

Beef production CH4 enteric CH4 manure N2O manure GHG emissions

Live weight gain (t) (t) (t) (kg) (t CO2 eq.)

BS 112.6 94.8 2.7 7.3 2,147.1 S1 148.3 65.6 1.8 5.7 1,484.2 S2 164.7 59.7 1.5 5.8 1,347.9 S3 157.8 61.2 1.6 6.3 1,383.3 S4 164.9 55.7 1.3 6.7 1,256.1 S5 214 67.8 1.8 6.9 1,533.3 S6 240.2 63.8 1.5 7.7 1,437.5 S7 240.2 60.5 1.8 7.5 1,373.9 S8 214 67.8 1.8 6.9 1,533.3 S9 240.2 63.8 1.4 7.7 1,437.5 S10 240.2 60.5 1.8 7.5 1,373.9

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

1

Table 5 – Potential impact of gradual increments of root / shoot ratio on climate change of the short term scenarios in kg CO2 eq. (kg LWG)-1.

Root / shoot ratio

1.6 1.7 2.3 2.9 S1 4.7 - - -0,02 S2 3.2 - - -0,87 S3 1.9 - -0,56 -2,62 S4 1.8 - -0,25 -1,96 S5 0.3 -0,09 - -4,22 S6 0.12 -0,17 - -3,58 S7 0.11 -0,16 - -3,41

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

Figure 1 – Region characterized. Source: Pillar et al. (2012).

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

Figure 2 – System boundaries for the baseline (A) and other scenarios (B). Source: Dick et al. (2014) adapted.

A B

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

Figure 3 – Inventory (schematic) of climate change (Cc), land use (Lu) and fossil depletion (Fd) in the different scenarios: expressed in percentage (100% = maximum absolute values).

MANUSCRIP

T

ACCEPTED

ACCEPTED MANUSCRIPT

Highlights

Productive improvements and environmental protection are not contradictory.

Improvements in forage-livestock systems result in reduced GHG emissions, land use and fossil depletion.

Rotational grazing contributes to mitigation of environmental impacts of southern Brazilian farms.

Reproductive improvements contribute to the reduction of GHG emissions and land use.

Introduction of legumes to replace nitrogen fertilizers have positive impacts on the environment.