by Grace Reckers
Greenhouse gasses (GHG) constitute a number of gasses (CO2 being the most prevalent) that are released from the earth’s surface and trap heat in the atmosphere. They have become of primary interest to many environmentalists because of their impacts on agriculture, human health, ecology, and other environmental systems. Countries across the world have committed to reducing GHG emissions due to general increased recognition of their detrimental effects. One such country, Brazil, aims for a 37% reduction of their 2005 emission values by 2025. As the second-largest producer of beef in the world, Brazil has acknowledged the notable fraction of GHG emissions derived from livestock production (18% of Brazil’s annual GHG) and the particular relation between the effects of cattle ranching and beef production on national emissions.
Agricultural experts have identified a number of different farming techniques that could potentially reduce GHG emissions through a process known as intensification. The practices involved in intensification are meant to make beef production more efficient both by increasing the amount of beef produced as well as by decreasing GHG emissions measured from the cattle industry each year. These emissions come from a number of different sources related to beef production, whether derived from the cows themselves or from the products and conditions necessary for the cattle industry.
The ultimate aim of intensification is to be able to stock more cows per hectare of farmland and to reduce the slaughter age. This is achieved through improving pasture management by rotational grazing and addition of nutrients to the soil, and by increasing the productive output of cattle through supplements and feedlots. These two intensification practices, used in tandem, have the potential to produce more beef per farm and to reduce overall emissions.
Bogaerts et al. (2016) surveyed 40 cattle farms across five northern municipalities of Brazil, 21 of which operated farms without sustainability programs, and 19 of which operated farms with sustainability programs. Four of these sustainability programs were identified as such due to their ability to work closely with cattle farmers to develop environmentally considerate management practices, and one of these programs was identified from its certification rewarding sustainable management. Each of the sustainable programs identified in the study aimed to improve cattle productivity by lowering the slaughter age and by increasing the stocking rates of cattle, and to promote better pasture management through pasture rehabilitation and rotational grazing.
In order to control for other characteristics that differed between farms, Bogaerts et al. used qualitative assessments of the geographic proximity, kind of operation, and operation size at each program and non-program site and ensured comparability in these characteristics. Emission rates were then measured for each program and non-program farm using the Cool Farm Tool to calculate GHG that derived from beef production processes and from the cattle themselves. This tool measured GHG that came from manure deposits, fertilizer manufacturing, pesticide manufacturing, feed production, enteric fermentation (cattle CH4 emissions), and N2O from fertilizer left on soil. These rates were then categorized into two sources of emissions: those directly from beef production, calculated into a measurement of emissions per kilogram of beef production (kg of CO2e/kg of beef produced); and those from contributions of the land, calculated into a measurement of emissions per hectare of pasture (kg of CO2e/ha/yr). The rates of emissions from program and non-program farms were compared for both categories once farm size, location, number of cows, years farm had been owned, and area of pasture had been controlled for through a series of linear regressions. These other explanatory factors that may otherwise have played a part in differences in emissions either per kg of beef produced or per hectare of pasture were demonstrated not to be statistically significant, meaning that each of the 40 identified farms were comparable in terms of farm characteristics.
Analysis of GHG emission rates per kilogram of beef produced in Bogaerts et al. demonstrated a 18.6% reduction in emissions per kg of beef produced on program farms when compared to that of non-program farms. This came from the 44.7 (±21.4) kg of CO2e/kg of beef produced on non-program farms measured against the 36.4 (±14.6) kg of CO2e/kg of beef produced on program farms. The difference in emission rates was not statistically significant.
Bogaerts et al. then compared GHG emissions per hectare of pasture between program and non-program farms and found that program farms had on average 4,552.2 (±2,106.6) kg of CO2e/ha/yr, while non-program farms had on average 4,483.5 (±3,397.2) kg of CO2e/ha/yr. This indicated a 67.8 kg of CO2e/ha/yr difference in emissions per hectare of pasture between program and non-program farms, which was not statistically significant, and was presumably due to the greater animals per hectare found on program farms (2.25 (±0.9) animals per hectare) compared to that of non-program farms (1.92 (±1.4) animals per hectare).
Finally, total GHG emissions per year were calculated from adding up all sources and measurements of emissions for each category of farm. For farms with sustainability programs, the median total emissions per year were 2,081.6 tCO2e. The total emissions for farms without programs were 2,512.4 tCO2e per year. This took into account emissions from enteric fermentation, manure, fertilizers, pesticides, and feed. Overall, there was a small reduction in GHG emissions for farms that participated in sustainability programs, although this reduction was not statistically significant at each measure of source of emission. While the initial data on emissions per hectare indicated that program farms actually had greater emissions than per hectare GHG on non-program farms, this did not take into account the improvements in pasture management and productivity that favored program farms and were measured in the per-kg emissions that were smaller for program farms.
Evidence of increased productivity and reduced emissions on Brazilian farms participating in sustainability programs demonstrates a forecasted transition from conventional Brazilian open pasture farming to the new practices of intensification, even when the differences between emission rates were not statistically significant. This becomes more compelling when looking at the increased herd size of program farms after participating in the sustainability programs for multiple years in a row, where stocking rates increased by 23% for program farms and slaughter age decreased by 3.4 months. This allows farmers to practice more efficient beef production while potentially reduction their GHG emissions. However, this comes at the cost of a loss of conventional farming practices. No longer are Brazilian farmers encouraged to raise cattle on open pastures; but there is now an emphasis on cramming in as many cows as productively possible on smaller plots of land, and on settling on younger ages at which to slaughter the cattle for beef production. The benefit of using less land, however, is not only that it emits fewer emissions due to production, but also that it leads to less deforestation, an issue of growing concern whose relation to GHG emissions has been studied but not discussed in the Bogaert et al. study.
Bogaerts, M., Cirhigiri, L., Robinson, I., Rodkin, M., Hajjar, R., Costa, C., Newton, P., 2016. Climate change mitigation through intensified pasture management: Estimating greenhouse gas emissions on cattle farms in the Brazilian Amazon. CGIAR 188 https://ccafs.cgiar.org/publications/climate-change-mitigation-through-intensified-pasture-management-estimating-greenhouse#.WI9YXrYrKb8.