Inverting the carbon footprint in Brazilian agriculture: an estimate of the effects of the ABC plan.

The Sectoral Plan of Mitigation and Adaptation to Climate Change in order to consolidate an Economy of Low Carbon Emissions in Agriculture (ABC Plan) integrates the commitments made by Brazil to mitigate its emissions of greenhouse gases (GHG). The objective of this study was to estimate GHG emissions from the agriculture and livestock sector considering the adoption of three low carbon emission technologies (LCT) – pasture recovery, integrated crop-livestock systems (ICLS) and the integrated crop-livestock-forest systems (ICLFS). The GHG emissions were estimated considering the growth projections of the production of soybean, corn, rice, beans, cotton, wheat, sugarcane and pastures from 2012 to 2023. Two scenarios were considered: I - without the adoption of LCT; II - with adoption of LCT, proposed by the ABC Plan. In scenario I, the cumulative emissions estimated were 670.47 million tCO 2 eq, with only about 22.67 million tCO 2 eq from agricultural activities. In the scenario II, the stock of carbon in the soil was higher than carbon emissions and would be 1.10 billion tCO 2 eq, with recovery of 75% of degraded pastures areas and implementation of ICLS and ICLFS in 25% of the area of degraded pastures. It was estimated that 52 million of cattle heads would be added to the Brazilian production system with adoption of the LCT. We concluded that technologies proposed by the ABC Plan can mitigate climate change and the Brazilian agricultural sector can reduce its carbon footprint and become the main sector in mitigating emissions.


INTRODUCTION
. Pastures correspond to 172 million hectares, of which an estimated 50% is in the process of degradation and 25% would be moderately degraded (Dias-Filho, 2014).Much of this cattle breeding is still extensive due to the great area with pastures in Brazil.
Reducing the productivity and quality of forage and soil carbon stocks and the low level of animal productivity may result in more GHG emissions per unit of product in that system.
Given the sector's relevance to the Brazilian economy, the transition from the current model of agricultural production to a low-carbon model is urgent.
The Low Carbon Agriculture Plan (ABC Plan) is a policy of the Brazilian federal government launched in 2010 comprising actions aiming to reduce GHG emissions in agriculture (Brasil, 2012).The scope of the Plan is to finance low-GHG emissions technologies.
The agricultural sector is the second largest emitter of GHG in Brazil, according to the Third National Inventory of GHG Emissions (Brasil, 2016).There was an increase between 2005 and 2010 from 415,754 million to 472,734 million tons of CO 2 eq.With the growing world demand for food increasingly pressing for agricultural expansion, these emissions tend to increase even more.
On the other hand, the sector, due to its characteristics and its sensitivity to the climate, is also one of the most vulnerable sectors to climate change (Yohannes, 2016).
Food production is an absolute priority for society, and mitigating climate change has the strategic interest of promoting food security.
Pasture recovery is considered a reference to estimate the reduction of GHG emissions in the agricultural sector.It is a set of techniques applied to improve pasture productivity.Such techniques provide the system with a greater carbon stock compared to a degraded pasture because the emission of CO 2 by the soil to the atmosphere occurs mainly by the decomposition of organic waste and the respiration of organisms from degraded areas (Carvalho et al., 2010).The balance between inputs of C through plant residues and losses of C, primarily through decomposition, is directly related to soil C levels (Paustian et al., 2000).Increasing cropping intensification and plant production efficiency may contribute to reduced CO 2 emissions by agricultural soils.Therefore, Brazilian agribusiness, besides providing food, raw materials and energy, balancing trade and generating jobs for the country, could contribute to the reduction of GHG emissions.

MATERIALS AND METHODS
The estimates of the balance of GHG emissions in agriculture were based on MMA (Brasil, 2015).
The sources of emissions were agriculture emissions of methane (CH 4 ), nitrous oxide (N 2 O) and carbon dioxide (CO 2 ).The N sources, transformed in (N 2 O), were grazing animals, crop residues, manure management systems (excluding pastures), atmospheric deposition of volatilized N (indirect emissions), and burning of sugarcane and cotton residues in the Northeast region of Brazil.The sources of CH 4 were rice cultivation, enteric fermentation of cattle, manure management, and burning of sugarcane residues in the Northeast.
The application of urea to the soil was considered a source of N, transformed in N 2 O, and the sources of CO 2 were the practices and systems of soil management used for conventional agriculture.
For the projections of crop production growth from 2012 to 2023, we considered data from the Ministry of Agriculture, Livestock and Food Supply -MAPA (Brasil, 2013) for soybean, corn, rice, beans, cotton, wheat, sugarcane and pastures.
In this work, we considered the GHG emission balance of the agriculture and livestock sector, that is, all the emissions and all CO 2 eq sinks resulting from the production system, unlike the Brazilian Emissions Inventory methodology (Brasil, 2015), which only considers the emissions of the activity in a disaggregated way.For example, for livestock activity, the Inventory considers the emissions per animal (N 2 O and CH 4 only) and does not consider the possible carbon stored in the soil in low carbon productive systems (Brasil, 2015).
The ABC Plan aims to reach, above all, those rural landowners and agricultural regions with a low technology adoption and/or degraded areas.Therefore, we assumed that the advance of the technologies of the ABC Plan, mainly pasture recovery, ICLS and ICLFS, will take place in these degraded regions as pointed by Assad et al. (2015).

GHG Estimates without Adoption of LCT -Scenario I
Additionally, for the calculation of the emissions, we considered that the expansion of the conventional agriculture projected until 2023 shall take place in degraded pasture areas, with a carrying capacity lower than or equal to 0.70 AU/ha, according to Dias-Filho (2014) and Assad et al. (2015).The IBGE's municipal base (Instituto Brasileiro de Geografia e Estatística, 2006) was used to determine municipalities presenting this average.Thus, we considered the agricultural areas of the selected crops only of the municipalities with degraded pastures.For livestock emissions estimates, we considered a constant number of cattle and low carrying capacity until 2023 in the municipalities with degraded pastures.
Emissions were calculated using the Global Warming Potential (GWP) metrics (Manning et al., 2009), which considers the influence of gases on changes in the Earth´s energy balance measured for hundred-year periods.

GHG Estimates with Adoption of LCT -Scenario II
To evaluate the GHG balance up to 2023 with the adoption of LCT in areas of agricultural expansion according to MAPA (Brasil, 2013), the following technologies were considered: pasture recovery, crop-livestock integration (ICLS), integrated crop-livestock-forest system (ICLFS).
In order to compare GHG emissions from agriculture with (scenario 2) and without the adoption of LCT (scenario 1), we analyzed only part of the Brazilian territory, excluding the Amazon biome.For estimates of mitigation through pasture recovery and the implementation of ICLS and ICLFS, we assumed that: i) 75% of degraded pasture areas would be recovered; in the remaining 25%, other integrated systems such as the ICLS and the ICLFS would be implemented; ii) crop expansion, considered until 2023, will take place on 25% of the degraded pasture areas through integrated production systems such as the ICLS and ICLFS.The crops considered were soybean, corn, rice, beans, wheat and pastures.These crops may make up the ICLS and ICLFS systems and are far more representative when compared to the total cultivated area in Brazil; iii) for estimates of emissions related to the change of land use, a soil carbon rate of 1 tC/ha/year was considered for the conversion of degraded pastures into productive pastures; and iv) for estimates of emissions related to the conversion of degraded pasture into ICLS and ICLFS, a soil carbon rate of 1.5 tC/ha/year was considered.

GHG Estimates without the Adoption of LCT
By analyzing the agriculture growth projections, it is evident that, for all crops analyzed, the tendency was to increase production between 2012/13 and 2022/23 (Table 1).According to MAPA projections (Brasil, 2013), the crops with the highest growth rates are cotton, sugarcane, soybean and corn, followed by wheat, beans and rice.IBGE's municipal base pointed that 1,285 municipalities had less than or exactly 0.7 AU/ha (Instituto Brasileiro de Geografia e Estatística, 2006).The extent of degraded pasture is 52.32 million hectares in Brazil as a whole, and there were 39,791,956 cattle, about 20% of the total Brazilian cattle herd.The main regions for pasture recovery or advancement of low-carbon agriculture are the Midwest (Mato Grosso do Sul, Mato Grosso and Goiás), which concentrates 34.7% of the national herd and 23% of the total degraded pasture; the Southeast (mainly the Minas Gerais state), which concentrates 18% of the national herd and 36% of the total degraded pasture; and the Northeast (mainly the Bahia state), with the largest areas of degraded pasture (Table 2).
According to MAPA projections (Brasil, 2013), the estimated cumulative emissions for Brazilian agriculture (livestock and agricultural activities) in the selected municipalities and in the studied period (11 years, from 2012/2013 to 2022/2023) were 670.47 million tCO 2 eq, with only about 22.67 million tCO 2 eq from agricultural activities (Table 3).
Notably, the number of cattle was the main source of GHG emissions in the projected scenario for the selected municipalities considering low carbon emissions technologies (Table 3), corroborating the data of the Brazilian Inventory of Emissions (Brasil, 2015).In addition,

GHG Estimates with the Adoption of LCT
Considering the premises assumed here and agriculture growth projections made by MAPA (Brasil, 2013), it would be possible to avoid the emission of 1 N 2 O warming potential is 298 times greater than CO 2.
670 million tons of CO 2 eq and further store 1.10 billion tons of CO 2 eq in the soil (about 100.2 million tons per year), according to the GWP calculation metric as adopted by the IPCC for this type of analysis (Table 4), using the technology to pasture recovery applied to 75% of the degraded pasture land area and the implementation of the ICLS and ICLFS in the remaining 25%.
The simulation made here is conservative, as it does not consider other technologies of the ABC Plan, such as biological nitrogen fixation in crops in addition to those of soybean, and encompasses only 1,285 Brazilian municipalities with degraded pasture lands (which have 0.7 animal units per hectare), considering bovine herds and only seven agricultural crops.Even so, in the breakdown per region, the Southeast, for example, could avoid the emission of 214 million tCO2eq (Table 3) and store around 434 million tCO2eq (Table 4) in the soil using pasture regeneration.The states that would emit GHG the most in a scenario without the expansion of ABC technologies are those that neutralize emissions the most according to the mitigation scenario.
It is important to highlight that the South region presented the lowest degraded pasture area (Table 2).
Therefore, the expansion of rice, one of the main crops planted in this region, in around 11% between 2012/13 and 2022/23 (Table 1) using LCT will occur in a smaller area compared to the other regions of Brazil.For the other regions, the negative sign (Table 4) represents carbon sequestration in the soil with the expansion of LCT in degraded pasture areas.
Thus, the potential for mitigation of agriculture GHG emissions of 1.8 billion tCO2eq (avoided emissions plus CO2eq stocks in soil) in eleven years through pasture recovery, ICLS and ICLFS (Figure 1) applied to 52 million ha of pastures with a low carrying capacity (< 0.7 AU/ha) is much higher than the goals stipulated by the ABC Plan and the NDC, indicating that Brazilian agriculture is fully capable of being transformed from a strong GHG emitter into an efficient GHG mitigating agent.
In terms of agriculture, the ABC Plan sets the goal of reducing 166 million tCO2eq by 2020 (Brasil, 2012), and the Brazilian NDC sets the emission reduction target of CO2eq at 37% and 43%, below 2005 levels in 2025 and 2030, respectively (Brasil, 2015).The agriculture  -626,200.92 -56.8 Int.
Moreover, it is possible to estimate the number of cattle that would be added to the Brazilian production system in those 52 million hectares of degraded pastures or pastures in the process of degradation.Through recovery of 75% of the degraded pasture area, there would be an additional of 0.70 to 1.5 animal unit by hectare (AU/ha) in 39 million ha, totaling an additional 29.3 million cattle.In addition, most importantly, emissions would be neutralized with the advantage of storing more carbon in the system and without the opening of new areas, the so-called land-sparing effect (De Lima, 2017).
If 25% of the degraded pasture area were used for integrated systems such as ICLS and ICLFS, which have a greater productivity than the forage systems in monoculture (Balbino et al., 2011;Vilela et al., 2011)  50 with an intensified production in recovered pastures when compared to farms with degraded or non-intensified pastures.In other words, increasing cattle productivity while stopping the conversion of natural environments would be a major contribution to tackling climate change.

CONCLUSIONS
The potential to mitigate GHG emissions by the Changes in the Earth´s climate may become one of the greatest environmental challenges ever faced by humanity.The consequences of possible increases in temperature and changes in rainfall patterns are concerning, and may cause systemic and irreversible damage to individuals and nations (Intergovernmental Panel on Climate Change, 2007).To face these problems, it is necessary to find political, economic and technological solutions that enable the reduction of greenhouse gas (GHG) emissions and the economic growth with respect to the environment (Intergovernmental Panel on Climate Change, 2014).Agribusiness is a very important sector in the Brazilian economy, since it represents 25% of the gross domestic product.Since 2008, Brazil is one of the largest exporters of agricultural products in the world.It ranks first in sugar, chicken meat, coffee, orange juice, tobacco and alcohol; second in beef, soybean and corn; and is the fourth exporter of pork.Grain production accounted for 186,610 million tons in 2015/2016 distributed into 58,336 million hectares; livestock farming occupies 25% of the total area of Brazil (Companhia Nacional de -chave: mudanças climáticas, mitigação, carbono do solo.45 In this context, it is essential to know and assess the potential contribution of Brazilian agriculture to climate change mitigation.In addition to the ABC Plan, this study can contribute to evaluate the potential of agriculture to reach the Brazilian goal of the COP 21, i.e., the Nationally Determined Contributions (NDC).The objective of this study is to estimate GHG emissions by the agriculture and livestock sector considering the adoption of three low carbon emission technologies (LCT) -pasture recovery, integrated crop-livestock systems (ICLS) and the integrated crop-livestock-forest systems (ICLFS) -to mitigate climate change from 2012 to 2023.

Figure 1 .
Figure 1.Agricultural CO 2 eq emissions estimated from 2012/13 to 2022/23 for different scenarios: without (without ABC Plan) and with the adoption of low-carbon technologies (with ABC Plan), Nationally Determined Contribution for 2025 (NDC 2025) and for 2030 (NDC 2030), and emission reduction goals of the ABC Plan until 2020.NDC = Intended Nationally Determined Contribution; NDC 2025 = emission reduction target of CO 2 eq in 2025 by 37% below 2005 levels; NDC 2030 = emission reduction target of CO 2 eq in 2030 by 43% below 2005 levels.ABC Plan 2020 = emission reduction target of CO 2 eq in 2020.
Brazilian livestock and agriculture is more than ten-fold the goal set forth by the ABC Plan.From 2012 to 2023, it will be possible to reach 1.8 billion tons of CO 2 equivalent (tCO 2 eq) by incorporating the emissions avoided and the carbon stored in the soil through the adoption of three technologies advocated by the ABC Plan (pasture recovery, integrated crop-livestock systems and the integrated crop-livestock-forest systems) in 52 million hectares of degraded pasture lands.It was possible to estimate the number of cattle that would be added to the Brazilian production system in those 52 million hectares of degraded pastures or pastures in the process of degradation, totaling an additional 29.3 million cattle.Currently, 80 million hectares of the national territory are cultivated with crops and 172 million with pasture, summing about 30 percent of the total.With the sustainable tropical technology, with competent and competitive rural producers, Brazil is fully apt to take advantage of the huge opportunity that arises with the growing worldwide demand for agribusiness products.

Table 2 .
Degraded pasture areas and number of cattle in the Brazilian regions.

Table 3 .
Cumulative emissions (2012Cumulative emissions ( /2013Cumulative emissions (  to 2022Cumulative emissions ( /2023)), in thousands of tCO 2 eq, and percentage of total emissions using MAPA projections and GWP metrics for each geopolitical region of Brazil and for the country, according to selected municipalities in Brazil, in the scenario of no adoption of low carbon emissions technologies listed in the ABC Plan.

Table 4 .
Balance of agriculture cumulative GHG emissions (2012/2013 to 2022/2023), in thousands of tCO 2 eq, for the selected municipalities in Brazil with the adoption of low-carbon technologies in areas of degraded pasture (being 75% with recovery and 25% with ICLS/ICLFS) using the GWP metrics and projections made byMAPA (Brasil, 2013).