When I was taking a massive open online course hosted by Esri in end-August, one of the activities required us to monitor the impact of livestock grazing on water quality in Oregon, United States of America. Personally, I think we may need to give more attention to the nonpoint-source water pollution caused by livestock grazing. And the problem is not just limited to cattle – even chicken, which is often touted as a more environmentally-friendly option, can facilitate freshwater pollution.
The Food and Agriculture Organisation of the United Nations and International Water Management Institute (2017, pp. 3-4) observe that livestock systems and aquaculture have been placing increased amounts of pressure on water quality, due to the increased global demand for food. A part of this may be attributed to the improper treatment and disposal of animal waste, a problem which is exacerbated by livestock grazing. Interestingly, the National Resources Defense Council (2019) notes that while animal waste from cows and pigs is rich in ammonia, poultry waste tends to contain a higher concentration of phosphorus instead.
Despite the benefits of allowing animals to roam freely within a portion of farmland, livestock grazing inadvertently results in the spread of animal waste across a larger area of land as compared to confining the livestock in narrow quarters. In cases where the livestock are allowed to roam freely near water sources, the risk of water pollution increases as animals may shed their waste in close proximity to the water, hence allowing particles of ammonia, phosphorus and pathogens to enter the rivers and streams.
In addition, the Food and Agriculture Organisation of the United Nations and International Water Management Institute (2017, p. 15) also suggest that overgrazing may aggravate soil erosion, particularly in regions with low vegetation, steep slopes and high precipitation. This may lead to increased sedimentation in nearby water sources, which adds another layer to the problem.
Given the above scenarios, it is fitting that environmental and agricultural agencies have prompted farmers to keep their livestock away from water sources as much as they can. The Environment Agency of the United Kingdom (2018) has instructed farmers to prevent their livestock from coming within ten metres of inland freshwater sources or coastal waters, as well as within 50 metres of springs, wells and boreholes.
Similarly, the United States Environmental Protection Agency (2020) emphasises the importance of fencing in ensuring the cleanliness of nearby streams, and even encourages farmers to plant field buffers along water bodies for additional support. But wait – could this possibly backfire? As much as plant buffers such as grasses and shrubs may be capable of filtering nutrients before they reach the water (United States Environmental Protection Agency, 2020), we do not know if certain varieties may exacerbate water pollution. Please let me know if you have any thoughts on this, and we can discuss this issue further.
Please stay tuned for a few more posts on agriculture, before we move on to another part of our food system!
See you soon,
Jialing
Reference List
Environment Agency of the United Kingdom (2018) Rules for farmers and land managers to prevent water pollution. Available at: https://www.gov.uk/guidance/rules-for-farmers-and-land-managers-to-prevent-water-pollution (Accessed: 1 October 2020).
Food and Agriculture Organisation of the United Nations and International Water Management Institute (2017) Water pollution from agriculture: a global review. Available at: http://www.fao.org/3/a-i7754e.pdf%20 (Accessed: 30 September 2020).
National Resources Defense Council (2019) Industrial Agricultural Pollution 101. Available at: https://www.nrdc.org/stories/industrial-agricultural-pollution-101 (Accessed: 30 September 2020).
United States Environmental Protection Agency (2020) The Sources and Solutions: Agriculture. Available at: https://www.epa.gov/nutrientpollution/sources-and-solutions-agriculture (Accessed: 24 September 2020).