Interventions to Decrease Loss of Reactive Nitrogen to the Environment

At the Resources for the Future website, I came across a recent commentary piece on reactive nitrogen by Andrew Manale, a researcher with the U.S. EPA's Office of Policy, Economics, and Innovation. It is an important topic, one that deserves greater attention. Here is Manale:

Before the discovery in 1909 by the German chemist Fritz Haber of a ready means for capturing large quantities of rN from the air, societies recycled it. Human "night soil" and animal manure was captured and applied to the land to fertilize plants. ...

Excess rN causes myriad environmental problems. It contributes to the formation of ozone, a major air pollutant. Too much of it as a fertilizer reduces the biodiversity of ecosystems. ... The excess rN that causes hypoxia (low oxygen levels) in marine environments now accounts for over 200—and growing—dead zones around the world, a number that has doubled in just 10 years. 

Humans have more than doubled the total annual global production of rN over natural levels, a rate that is accelerating. Fertilizer, the major source of rN, accounts for some 38 percent that is anthropogenically introduced. Other sources include burning of biomass, land clearing, and the draining of wetlands, all of which release stored (sequestered) rN back into the environment (33 percent); legumes, such as soybeans (19 percent); and combustion of fossil fuels (10 percent and growing).

A year ago, Science published two notable articles on the topic, "Transformation of the Nitrogen Cycle: Recent Trends, Questions, and Potential Solutions" and "Impacts of Atmospheric Anthropogenic Nitrogen on the Open Ocean." They were reported on at the time by Brandon Keim in the Wired Science blog.

In the supporting online material for the "Transformations" article (subscription only pdf), the authors identified four intervention points for decreasing loss of reactive nitrogen (Nr) to the environment: utilizing available technology to decrease Nr creation during fossil fuel combustion; increasing the nitrogen use efficiency of crop production; improving the genetic potential of animal feeding strategies and manure management; and sewage treatment.

Two years ago I joined a wiki-based discussion on reactive nitrogen hosted by the David and Lucile Packard Foundation. The discussion focused on the role of agriculture and there is good information about nitrogen use efficiency, along with other aspects of the issue. The follow up report on the "experiment in online collaboration" (pdf) is also available.