Agriculturalists in the United States are trialling new methods to reduce the amount of synthetic nitrogen used on maize crops. Although drought has hit this year’s crop hard, especially in the American Midwest, the United States remains the world’s number one exporter of maize.

However, maize is a nitrogen-loving plant. To achieve desired production levels, most U.S. farmers apply synthetic nitrogen fertiliser to their fields every year, which comes at an environmental as well as economic cost. Agricultural runoff is considered to be the main contributor to dead zones which appear off the coasts of certain States each year; the sector accounts for almost 70 per cent of all anthropogenic nitrous oxide emissions.

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In response to this, scientists at the National Science Foundation have conducted research into reducing and better targeting fertiliser use. Although best practice is already followed throughout much of the US and farmers strive to avoid large losses of fertiliser, according to the NSF, the organisation revealed that attempts to go beyond and reduce losses further currently cost more money than the fertiliser saves.

NSF investigator Phil Robertson of Michigan State University is currently working on a programme which would pay farmers to apply less nitrogen, thereby making the time and expense of efforts to mitigate fertiliser loss more worthwhile. Robertson assures his programme, the Nitrous Oxide Greenhouse Gas Reduction Methodology, will not jeopardise yields.  

In soils, the production of nitrous oxide through microbial activity is a natural process, but applying large amounts of fertiliser greatly increases the amount of nitrous oxide which is released; the gas lasts for around 100 years in the atmosphere and has 300 times the heat trapping effect of carbon dioxide. More of the gas is released when nitrogen fertiliser is added in larger amounts than the crop needs, and when it is applied at times or in ways that make it difficult for the crop to get the full benefit. Robertson explained, "Improving the efficiency of nitrogen use for field crop agriculture holds great promise for helping mitigate climate change."

The methodology divides by NSF scientists is in the final stages of validation in the United States.

However, although such economic incentives have proven popular with farmers in trials, the practice of applying a market-based approach to the problem of pollution has received heavy criticism in the past.   

Scientists and social justice campaigners have argued that the approach encourages a ‘business as usual’ attitude, which, as climate action campaigner Larry Lohmann explained in the New Scientist, means richer and often heavier polluters start at an advantage and can consolidate their position, with little change to their impact on the environment or overall levels of pollution.

Critics suggest that, in the worst cases, problems of imbalance in emissions trading can lead to perverse incentives and distract from the need to decrease pollution and find viable non-polluting alternatives.

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