Fixing Nitrogen, Waste

By William Kusch

irina-sorokina-253176footprint grass

Figure 1: What is your nitrogen footprint?

You may be familiar with the concept of carbon footprint, but when was the last time you measured your nitrogen footprint? If you are like me, up until very recently, the answer to that question would be: “huh?”.

I got to thinking about the topic when I read an article[1] that National Public Radio (NPR) published, profiling research on life cycle analysis (LCA) of producing a loaf of bread. The article concluded that 66% of greenhouse gas emissions were not from transportation, or baking, but from growing the wheat itself.  Further, “of the environmental impacts … 40% is attributable just to the use of ammonium nitrate fertilizers alone.”

Intrigued, I read on, re-read my colleague’s excellent blog post on animal and livestock nutrition, then clicked my way to a related article[2], also on NPR that dove deeper than greenhouse gas emissions. This story looked specifically at the nitrogen pollution linked to agriculture, with an emphasis on meat production. This piece outlined some agricultural sources and forms of this significant pollutant:

  • Gaseous emissions of nitrogen oxides (NOx) from livestock
  • Release of N2O, and NOx from soil microbes
  • Runoff from excess fertilizer applied to farm fields.

Well, you may say, so what? Isn’t most of the air we breathe nitrogen anyway?  While it is true that a large majority of the atmosphere is nitrogen, it comes in the form of inert N2. N2 is far different from N2O and NOx , two recognized pollutants. Here are a couple of the potential implications from the release and accumulation of N2O and/or NOx:

  • WK gulf mexico

    Figure 2: Image depicting marine dead zone in Gulf of Mexico

    Marine dead zones, such as the famous one in the Gulf of Mexico, where most ocean life has died due to lack of oxygen[3]

  • If concentration is elevated in drinking water, can lead to potentially fatal blue baby syndrome, other negative health impacts[4]
  • Emissions of NOx can lead to the hazardous type of ozone that remains near ground level. This type of ozone can trigger health problems, especially for children and the elderly[5].

Given that agriculture is one of the biggest contributors to nitrogen pollution, and also that no one is going to stop eating in order to stop polluting, what can people do to reduce their nitrogen footprint? Fortunately there are some simple, and effective options to pare the amount of nitrogen pollution associated with our daily activities:

  • Average Americans “eat about 1.4 lbs of protein per week, 2/3 of which come from meat and dairy. …you could cut your nitrogen footprint by more than 40% just by reducing your total protein intake to 0.8 lbs, the amount recommended by the USDA and the National Academy of Sciences”.
  • Get creative with your spending power: think about ways you could change one meal a week from animal protein to one that is centered around plant protein such as that from chickpeas, or assorted beans.
  • Throw away less of your food: an estimate from Natural Resources Defense Council[6] indicates that America wastes ~40% of our food by throwing it in the garbage prematurely, or unnecessarily.
  • Encourage your legislators to support agricultural land conservation efforts, especially in areas where plants filter fertilizer runoff before it enters the local watershed.
  • Consider a more fuel efficient, or electric vehicle when choosing your next set of wheels: while agriculture is the largest source of N2O, transportation also accounts for a large share of NOx[7].
WK orchard

Figure 3: Nitrogen-fixing pongamia trees in TerViva’s Hawaii orchard

At TerViva, we’re doing our part to mitigate this global nitrogen problem as well. We are growing orchards of pongamia: oilseed-producing trees that are legumes and harness the power of symbiotic bacteria to capture nitrogen from the atmosphere. This ability to provide nitrogen for itself allows pongamia to be cultivated using significantly fewer costly inputs relative to most conventional crops, like nitrogen fertilizers. After we harvest the seeds, we crush the crop in an oilseed press, yielding oil and seed cake. The oil serves as an excellent feedstock for biofuel. The seed cake is high in protein and we have discovered how to convert the pongamia protein into animal feed. In addition to feeding livestock, pongamia seed cake can also be used as a fertilizer[8]; we know this because people have been using pongamia cake as fertilizer in Southern and Southeast Asia for many hundreds of years. The reason this anecdote is relevant here, is that modern scientific techniques have recently been brought to bear, analyzing and quantifying the value of pongamia seed cake as fertilizer. In fact, in addition to demonstrating the value of pongamia products as fertilizer, recently published research shows that if pongamia seed cake is used as a fertilizer, there are compounds in the fertilizer that prevent nitrogen pollution from happening in the first place when farmers apply fertilizer to their fields [9].

Through this idea of considering our Nitrogen Footprint, we at TerViva are exploring ways that we can provide renewable, plant-based energy and protein to society, while at the same time preventing and mitigating some of the issues that arise from the modern lifestyles that afford us comfort and convenience.

References:

[1] http://www.npr.org/sections/thesalt/2017/02/27/517531611/whats-the-environmental-footprint-of-a-loaf-of-bread-now-we-know

[2] http://www.npr.org/sections/thesalt/2016/02/25/467962593/why-your-hamburger-might-be-leading-to-nitrogen-pollution

[3] http://www.noaanews.noaa.gov/stories2015/080415-gulf-of-mexico-dead-zone-above-average.html

[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1638204/

[5] https://www.epa.gov/ozone-pollution

[6] https://www.nrdc.org/sites/default/files/wasted-food-IP.pdf

[7] http://www.pnas.org/content/100/4/1505.full.pdf

[8] http://oar.icrisat.org/424/1/IndJourFer5_2_25-26_29-32_2009.pdf

[9] http://nopr.niscair.res.in/bitstream/123456789/5647/1/NPR%207(1)%2058-67.pdf

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