ABSTRACT
Nitrogen inputs were a key component of the green revolution, which helped feed the world during the 20th century. Nonetheless, when nitrogen is applied at rates that are higher than recommended, the excess nitrogen increases the availability, mobility and losses of reactive nitrogen to the environment. There is an extensive body of literature that has reported on reactive nitrogen losses from agricultural systems across regions of the world, losses that are contributing to negative environmental impacts such as hypoxic zones, algae blooms and emissions of greenhouse gases that contribute to a changing climate, negative impacts to groundwater quality and several other environmental impacts. Reactive nitrogen losses to the environment have been reported to generate negative economic impacts such as the 1.7 billion dollars it costs to remove nitrate from agricultural sources to have safe drinking water[ 9 ] and the potential negative impacts on human health.[ 8 ] A great challenge that humanity faces in the 21st century is how to achieve food security for the additional 2.5 billion people that are expected to join this planet in the coming decades. Similarly, to nitrogen’s key role in feeding a growing world population during the 20th century, nitrogen inputs to maximize agricultural productivity will also be key in the 21st-century efforts to achieve food security. Humanity needs to learn from the errors of the 20th century that contributed to massive losses of nitrogen across different regions of the world and improve management of nitrogen. However, management will be even more challenging in the 21st century than in the 20th since humanity will be confronting a changing climate and the occurrence of more frequent extreme events, floods and droughts. One of the new management approaches that will provide a new alternative to farmers, conservationists and nutrient managers is the use of management practices to increase nitrogen use efficiencies at the field level and reduce transport of nitrogen and other nutrients to the environment from the edge of the farm. These reductions in nitrogen and nutrient losses could then be accounted for and “saved” in a system analogous to a bank account and be traded in ecosystem, air and water quality markets. There is potential to use trading and environmental payments in water and/or air quality programs to encourage farmers, nutrient managers, conservationists and organizations to apply improved management practices that maintain yields; reduce the transport of nitrogen, nutrients and sediment out of the farm via surface, leaching and gaseous pathways; and contribute to the sustainability of farms, cities, watersheds and the biosphere. This brings new opportunities to manage farms during the 21st century as a unit and implement practices not only in the field but also around the field in buffer areas using a combination of precision agriculture and precision conservation to reduce nutrient transport from the field and the edge of the farm and trade these savings (reduced losses) as a farm product in ecosystem markets (water and/or air quality programs). There is potential to use a nitrogen (nutrient) trading tool that is robust to quickly assess the potential reduction in nitrogen losses. The first nitrogen trading tool, defined as an NTT, was developed for the United State Department of Agriculture – Natural Resources Conservation Service (USDA NRCS) and released in 2008.[ 6 , 16 , 37 ]
The first version of the NTT was then replaced with a second version that could assess the potential to trade other nutrients and erosion savings: the new NTT, the Nutrient Tracking Tool.[ 18 ] Tools like this will be used to assess nitrogen (nutrient) management to increase use efficiencies and reductions of losses to the environment, and the use of these ecotechnologies will contribute to the trading of these savings in ecosystem marketplaces, contributing to additional income to farmers and ranchers and global sustainability during the 21st century.
