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Field Projects Show How Farmers Can Cut Nitrogen Emissions While Boosting Yields

Two new studies are shining a light on how farmers can reduce their use of nitrogen fertilizers—and control the climate-busting nitrous oxide they produce—while increasing farm yields and incomes.

“To ensure global food security, agriculture must increase productivity while reducing environmental impacts associated with chemical nitrogen fertilization,” writes the team behind one new study, which looked at the effects of replacing nitrogen inputs from chemical fertilizers with recycled organic waste. 

Published in Science of the Total Environment, the study focused how the replacement shifts the influence of microbial communities on crop yields and environmental impacts.

“The study is crucial to policy-making as it highlights the potential advantages of shifting toward systems balancing chemical and organic fertilizers with economic benefits for farmers, reduced environmental damage, and an efficient way for organic waste disposal,” write the researchers.

The results showed that “partial organic substitution improved crop yields, prevented soil acidification, and improved soil fertility.” And while the organic replacements increased the general diversity and abundance of microbes involved in nitrogen cycling and reduced nitrogen runoff and leaching, the researchers specifically noted an increase in species that reduce nitrous oxide emissions.

Nitrous oxide is 300 times more powerful a greenhouse gas than carbon dioxide, and a paper last fall found that global emissions are rising fast enough to push average warming to 3.0°C by 2100. “Even though the magnitude of the emissions… is less, the potency of the gas is much stronger,” University of East Anglia scientist Parvadha Suntharalingam told CBC at the time. “A little of it goes a long way.”

In the new study, a cost-benefit analysis showed that partially replacing inorganic with organic fertilizers “increased economic benefit per unit area by 37 to 46%, and reduced agricultural inputs and environmental impacts per unit product by 22 to 44%.” Aspiring agriculture entrepreneurs should note that replacing 50% of chemical fertilizer with pig manure was the most profitable strategy.

In another example of how research can help influence effective farm policy, “one of the world’s biggest and most impressive studies shows us that simple interventions can produce large results,” reports Our World in Data. 

The study team engaged with 21 million smallhold farmers in China over 10 years, designing strategies to increase crop yields while reducing environmental impacts from farming. The project produced a 10.8 to 11.5% increase in commodity grain yields despite a 14.7 to 18.1% reduction in fertilizer use. 

“This wasn’t achieved through major technological innovations or policy changes: it involved educating and training farmers on good management practices,” Our World in Data writes.