Improved pasture and herd management to reduce greenhouse gas emissions from a Brazilian beef production system
Introduction
Beef production systems are important sources of greenhouse gases (GHG) through emissions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). The emissions arise from enteric fermentation, manure handling, nitrogen fertilizer applications and soils. The Brazilian cattle herd is one of the largest in the world, responsible for 15% of beef production worldwide (FAO, 2012). The national beef production has increased six fold between 1950 and 2006. From 1950 until 1985 this increase was mainly related to an increase in land use, rather than productivity (Martha et al., 2012). Livestock farming in Brazil expanded into areas with poor infrastructure and depleted by the intensive production of crops (Veiga et al., 2004). From 1985 until now the Brazilian beef production increased due to improved technologies, such as genetics, health and pasture management. Although the total pasture area decreased (Martha et al., 2012), the average stocking rate is still around one animal unit (AU) per ha. In Brazil, pastures occupy about 180 million hectares, approximately three-quarters of the national agricultural area (Ferraz and Felicio, 2010).
There are at least two major challenges for the Brazilian beef production in the near future. First, competition for land will further increase over the next ten years. The agricultural area needs to expand by 20 million ha to meet the growing needs of food, feed and biofuels (Cerri et al., 2009). This expansion should preferably focus on using degraded pastures to avoid further deforestation. The average beef consumption in Brazil is 37.9 kg person−1 year−1 (Conab, 2014). There are projections of increased demand for beef in the order of 2.5% per year until 2017–2018 (Conab, 2014), increasing the pressure on pastureland as well. The second challenge is to increase beef production without further increasing GHG emissions. According to Cerri et al. (2009), livestock is the third largest emitter of GHGs in Brazil, surpassed only by the burning of fossil fuels and deforestation. As deforestation has reduced over the past years, the livestock sector will soon become the second largest source of GHGs. Brazil already has established GHG mitigation targets. In June 2010, the Low Carbon Agriculture Program (Programa ABC) was established. The programme aims to stimulate the development and adoption of more sustainable agricultural practices that reduce GHG emissions. Brazil has recently committed itself to a reduction of 36% in emissions by 2020 and the livestock sector is one of the main targets.
According to Carpentier et al. (2000), continuation of deforestation is a dead end, as it will further increase GHG emissions. The intensification of current production system seems to be a sensible strategy to achieve the goals of beef supply on a 20 million ha smaller area than currently used (Gouvello, 2010, Martha et al., 2012). The improvement of the whole system of beef production is essential to reduce emissions from all relevant sources, like land use, land use change and livestock (Bowman et al., 2012).
The main hypothesis of this study is that the intensification of beef production, through improved pasture and herd management, can reduce GHG emissions per unit of beef. The main objective of the present paper was to quantify the GHG gas emissions of different beef production systems in Brazil. Therefore we developed a whole farm model that allowed us to calculate GHG emissions from all-important sources for a beef production system in Brazil. The model is able to simulate different scenarios with varying intensities of pasture and herd management, and thus calculate the GHG emission in different intensification scenarios.
Section snippets
Climate and geographical location of the simulated farm
Brazil is a continental-size country, and beef systems are very different from north to south. The increase in beef production in the northern (Amazon) region is partly driven by the increase in pasture area, unlike other regions where the productivity of the beef enterprise is the main driver for the increased beef production (Martha et al., 2012). We focused our study on the northern region because improvement of the beef production system will represent an important prerequisite to reduce
Results
The technical results of the beef production system improved significantly with increasing intensification (Table 3). Intensification increased the number of calves, steers and heifers, especially in the herd intensification, decreased the total time spent to complete the six cycles and reduced the slaughter age of the steers. Compared to the baseline Extensive scenario, the pasture area decreased up to 92% in the Improved scenario, while beef production nearly doubled when both intensification
Discussion
Our results confirmed the initial hypothesis, as the more intensified systems showed a lower emission of CO2eq kg of carcass−1 (Table 5). Despite these reductions, the beef systems remain net sources of GHGs. Our results showed that the decrease in CH4 emission outweighs the impact of N2O and CO2 from application of nitrogen fertilizer and lime, decreasing the total CO2eq emission in the more intensified systems.
In recent years, there have been an increasing number of studies concerning GHG
Conclusion
The intensification of beef production, through improved pasture and herd management reduces the GHG emissions per unit of beef. As mentioned before, this study included only “on-farm” GHG emissions i.e., not accounting emission from the production of fertilizer, lime or other inputs. The intensification scenarios simulated in this study can be considered as important mitigation options, reducing the GHG emission per unit beef from 2% to 57%. The beef production in intensified systems required
Acknowledgement
This work was supported by Fundação de Amparo a Pesquisa do Estado de São Paulo (FAPESP 2010/00554-0).
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2022, Journal of Cleaner ProductionCitation Excerpt :This is in alignment with the results of Schmidt Rivera and Azapagic (2019) who estimated the GWP of a classic lasagne to be 5 kg CO2-eq, with beef being the main contributor with 83%. In our study enteric fermentation and methanogenic emissions from the rumen (55%), manure management (22%) and the use of fertilisers (17%), in particular N fertilisers, for feed production were the main contributors responsible for the high GWP of beef, as also found by previous LCA studies e.g. (Asem-Hiablie et al., 2019; Herrero et al., 2013; Mazzetto et al., 2015). The GWP of the vegetarian lasagne was 1/6th of the beef lasagne (0.92 kg CO2 eq), with cheese and milk as the main contributors, with 49% and 20% respectively.