Hypoxic Dead Zones and Agriculture
Bottom water hypoxia, also known as the cause of ocean dead zones, is a severe environmental problem. The phenomenon starts when excess nutrients, specifically nitrogen, flow into a body of water, feeding the cyanobacteria, a type of microscopic algae. The cyanobacteria feast out on so much food, and rapidly reproduce, depleting the waters of oxygen. This suffocates any aquatic animals that live below the layer of algae, including fish and bottom-dwelling organisms such as crabs, lobsters, and sea urchins. In extreme cases, this can kill thousands, sometimes even millions, of sea creatures.
|
Dead zones occur naturally, but scientists have observed that human activities accelerate the problem. Many plant-based advocates have tried to place the blame entirely on the “animal agriculture” industry, but that could not be further from the case. The truth is that it’s the dispersal of fertilizers onto crop fields that allows the nutrients to end up in rivers or streams that eventually transport them to larger bodies of water where the hypoxia will occur.
The scary truth is that many plants are not efficient enough at intaking the nitrogen (in certain conditions, barely 20% can actually be absorbed by the crops). Another major problem caused by un-absorbed nitrogen is that soil microbes convert it into nitrous oxide, an extremely troublesome greenhouse gas. Also, many crop fields are located in very close proximity to rivers because that’s where the soil is often more fertile. Groundwater or excess irrigation water carries the nitrogen to the river which will flow straight to a large lake, ocean, or estuary.
Furthermore, livestock manure (which is most commonly used in organic operations, but is also used even by the most progressive conventional farmers) actually has less potential to cause ocean dead zones than synthetic fertilizer does. This is because the nutrients in organic fertilizers (of which, livestock manure is the most common) take longer to be released and are present in lower concentrations.
The scary truth is that many plants are not efficient enough at intaking the nitrogen (in certain conditions, barely 20% can actually be absorbed by the crops). Another major problem caused by un-absorbed nitrogen is that soil microbes convert it into nitrous oxide, an extremely troublesome greenhouse gas. Also, many crop fields are located in very close proximity to rivers because that’s where the soil is often more fertile. Groundwater or excess irrigation water carries the nitrogen to the river which will flow straight to a large lake, ocean, or estuary.
Furthermore, livestock manure (which is most commonly used in organic operations, but is also used even by the most progressive conventional farmers) actually has less potential to cause ocean dead zones than synthetic fertilizer does. This is because the nutrients in organic fertilizers (of which, livestock manure is the most common) take longer to be released and are present in lower concentrations.
Another reason livestock manure has lower potential for contributing to hypoxia is that some of the nutrients are bound together in the form of chemical compounds, making them unusable to cyanobacteria unless they were retained by the soil allowing the microbes to have time to break the down. Organic fertilizers also improve soil structure, which can better retain all types of nutrients, meaning the soil itself would do a better job of preventing nitrogen from flowing out of the field and into waterways.
So what can we do? It’s not like we can just halt all production of food crops with an increasingly hungry world. Agronomists are researching ways to make crops intake more of the nitrogen provided to them by fertilizers. |
One way to do this was developed by the University of Alberta, who found that, through genetic manipulation, scientists can boost the “nitrogen metabolism,” or increase the amount of nitrogen the plant absorbs so less is available for pollution, of canola. They went on to develop the same benefits in corn, wheat, barley, soybeans, rice, cotton, alfalfa, and some trees. However, the science has unfortunately not been approved yet, so none of these crops are being grown for human consumption at this time. Hopefully, the technology will be investigated enough that it will be deemed safe and soon find its way into the market.
Other ways that environmental organizations are trying to combat bottom water hypoxia are by restoring wetlands, which can capture the nutrients before they make their way to the oceans, digging drainage ditches that act like man-made wetlands, catching the nitrogen before it can do harm, and educating citizens about lawn fertilization and irrigation techniques that can prevent nutrient runoff.
Other ways that environmental organizations are trying to combat bottom water hypoxia are by restoring wetlands, which can capture the nutrients before they make their way to the oceans, digging drainage ditches that act like man-made wetlands, catching the nitrogen before it can do harm, and educating citizens about lawn fertilization and irrigation techniques that can prevent nutrient runoff.