Discipline: environment; Keywords: greenhouse gas emissions, soil carbon, pasture, dairy farms.
Dairy has been targeted as a source of greenhouse gas emissions. However, research has shown that grazing livestock on pasture-based dairy farms restore carbon to the soil, enhancing its biodiversity and countering climate change. This poses the question: If farms can have a positive impact, but are also a source of negative impact, what is the net effect? This is an important consideration when assessing the negative contribution that dairy farming makes to climate change. Trace and Save in the Eastern Cape assist farmers with measurements on greenhouse gas emissions and soil carbon to assess the carbon balance. The aim of this study by them (referenced below) was to assess the relative impact of dairy farms on climate change by adding greenhouse gas emissions to soil carbon change. An increase in soil carbon is recorded as a negative emission, and therefore mitigates the impact of greenhouse gas emissions. The net emissions give a true indication of the impact of pasture-based dairy farms.
Soil carbon levels are assessed on farms annually, across the entire farm, by taking composite soil samples and analysing them for total carbon % (LECO). On these same farms, a carbon footprint assessment is carried out each year, which calculates the total greenhouse gas emissions resulting from the respective farming practices. These emissions are from practices both on-farm, and emissions caused by products bought by the farm. The measurement of both factors allows for the net carbon emissions assessment to be done. The assessment was completed on 45 farms, 44 across the Eastern Cape Province, and one in the Southern Cape.
The combined average trend of all 45 farms demonstrated an increase in soil carbon of 8.9 tons CO2e per ha per year and greenhouse gas emissions of 27.5 tons CO2e per ha per year. This indicates a net carbon emission of 18.6 tons CO2e per ha per year. In real terms, these 45 pasture-based dairy farms have a net negative effect which is 68% of what is generally understood and discussed. In total, there are seven farms which had negative net carbon emissions for the duration of this study. This should not detract from the emission impact of the other 38 farms, which remain a challenge. It should be noted that of these farms, only 15 of them are not making the positive contribution of increasing soil carbon.
These results are exciting for farmers, the dairy industry and for consumers. For farmers, it shows their commitment to becoming more sustainable. Increased soil carbon is also indicative of improved soil health, which is beneficial to farmers. It allows the dairy industry to redress the misrepresentation of dairy farmers only having negative environmental impacts. For consumers, it provides evidence of of positive actions taken by farmers to safeguard the environment farmers that should be supported and celebrated.
C. Galloway, 2020. South Africa: A journey towards negative net carbon emissions on dairy farms by building carbon sinks. In: 2020 IDF Dairy Sustainability Outlook • Issue N° 3, June 2020, page 26.