My point in that off-the-wall example: all of the subjects in school are interdependent on each other, and agriculture is no different. The vegan movement has attempted to popularize the idea that an agricultural system devoid of livestock production is the most sustainable option, but the truth is that crop production without farm animals would be very, very harmful to the environment. Specifically, livestock manure is one of the most eco-friendly fertilizers. In fact, it has become the leading option for organic producers. Here’s some science: “Fertility in the organic system depended on animal manure applications and winter cover crops; the two conventional systems received synthetic fertilizer inputs… After 4 yr, soils in the organic and low-input systems had higher soil organic C, soluble P, exchangeable K, and pH.” Clark, M Sean, et al. “Changes in Soil Chemical Properties Resulting from Organic and Low-Input Farming Practices.” AGRONOMY JOURNAL, vol. 90, doi:10.3897/bdj.4.e7720.figure2f. “A key resource in this respect is animal manure. Such manure can increase and maintain soil fertility by providing N, P, K, S, Ca, Mg, Na and other trace elements such as Fe, Mn, Cu, Zn. It also improves the pH of acid soils and calcareous soils, increases soil organic matter content and cation exchange capacity, improves soil aggregate stability, soil macro-structure, infiltration, water holding capacity and erosion resistance. However, animal manure cannot meet crop nutrient demand over large areas, because of the limited quantities available and the relatively low nutrient content of the materials. The combined use of animal manure and mineral fertilizers is, therefore, a promising alternative strategy.” Bayu, W., et al. “The Role of Animal Manure in Sustainable Soil Fertility Management in Sub-Saharan Africa: A Review.” Journal of Sustainable Agriculture, vol. 25, no. 2, 2005, pp. 113–136., doi:10.1300/j064v25n02_09. “Recycling of livestock manure in agroecosystems to partially substitute synthetic fertilizer nitrogen (N) input is recommended to alleviate the environmental degradation associated with synthetic N fertilization, which may also affect food security and soil greenhouse gas (GHG) emissions. Substituting livestock manure for synthetic N fertilizer (with equivalent N rate) significantly increased crop yield by 4.4% and significantly decreased Nr losses via NH3 emission by 26.8%, N leaching by 28.9% and N runoff by 26.2%. These results suggest that recycling of livestock manure in agroecosystems improves crop productivity, reduces Nr pollution and increases SOC storage. To attenuate the enhanced carbon source in paddy field, appropriate livestock manure management practices should be adopted.” Xia, Longlong, et al. “How Does Recycling of Livestock Manure in Agroecosystems Affect Crop Productivity, Reactive Nitrogen Losses, and Soil Carbon Balance?” Environmental Science & Technology, vol. 51, no. 13, 2017, pp. 7450–7457., doi:10.1021/acs.est.6b06470.
Another big example of how livestock production can make growing crops more sustainable is when farmers release cattle, sheep, or horses onto crop fields outside of their growing season. Not only does this distribute manure onto the land straight from the source, but animals tromping over the ground disturbs the soil, which improves organic matter, root strength, and water retention, while decreasing the chances of harmful nutrient runoff. As I discussed in a previous installment to this series, allowing livestock to inhabit land reduces the risks of wildfires.
All-in-all, crop production is most sustainable and abundant when it’s supplemented with livestock production. Without farm animals, the fruit and veggie aisle would be very lacking, and that is why the term, “animal agriculture” is misleading. Farm animals are integral to many other sectors of ag, especially the ones prefered by plant-based activists.
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