January 6, 2023
By Madeleine Resener, GeoPols
Nitrogen, one of the most plentiful gases in our environment, is both a friend and foe to our planet and to ourselves.
It makes up 45% of the nutrients used in fertilizers to grow corn, wheat, and soybeans. That’s why it is essential to crop output. However, nitrogen can be a pollutant – especially when it seeps into water supplies through agricultural run-off or leaching.
Researchers have been exploring various techniques to reduce the nitrogen that ends up in lakes, streams, and other bodies of water.
A promising approach is called “Drainage Water Recycling” (DWR), and it is the subject of a research project at Iowa State University led by Matthew Helmers, professor of agricultural and biosystems engineering and director of the Iowa Nutrient Research Center.
To support this research, Trammo recently made a contribution to the Hart Fund for Soil Research, which includes faculty studies in nitrogen management, carbon capture and water quality. The fund was started by Brent Hart, an alumnus of Iowa State and former CEO of Trammo, who retired from that post in October 2018.
DWR involves capturing excess water drained from fields, storing this drainage water in a pond, a reservoir, or a drainage ditch, and then using the stored water to irrigate fields when there is water deficit. The benefits include reduced exposure to weather volatility, increased crop yields from supplemental irrigation when moisture is short and improved downstream water quality.
Versions of DWR have been around for years, with limited adoption. But as growing conditions become ever more erratic, the system is starting to gain appeal and there is a need for continuing research.
The Iowa State University study has been applying DWR to three test sites in the Midwest, including one in Story County, Iowa. Installed in 2015, the DWR irrigation system has boosted corn yields by, on average 20%, in the four years where supplemental irrigation was used. In addition, the water and nutrients used for supplemental irrigation were kept from being lost to downstream waters.
The results are encouraging for farmers on the front lines of global warming. If there is one thing this year’s extreme weather has made clear, it is the notion that seasons are changing, with the future predicted to bring wetter springs and hotter, drier summers.
This will pose enormous challenges, since prolonged wet weather and historic flooding will disrupt spring planting while drought and record-breaking temperatures have the potential to dramatically reduce crop yields. Water and nitrogen management will be part of the necessary adaptation to these new climatic conditions.
“We have been looking at the impact of DWR in central Iowa, and we have developed models based on what we see in the fields,” says Helmers. “At this point we still need more research to see if DWR is economically feasible, but it’s clear that DWR potentially could increase farmers’ profitability by enhancing crop yields while reducing downstream nutrient delivery.”
Iowa State is not only innovating to find ways to reduce nitrogen, but also investigating how to improve nitrogen fertilizer management for the benefit of productivity, profitability, and environmental performance.
Agriculture accounts for more emissions than any economic sector in Iowa (31%). Of those, 75% comes from nitrous oxide (N2O), most of which comes from nitrogen fertilizer. The most effective way to reduce N2O emissions is to better manage nitrogen fertilizer. But forecasting optimum nitrogen fertilizer rates is incredibly difficult - optimum rates can vary by more than 100% from field-to-field and year-to-year.
Michael Castellano, professor of agronomy, is one of the principal investigators of the Iowa Nitrogen Initiative. The Initiative has created a unique public-private partnership among Iowa State researchers, farmers, and their advisors to conduct hundreds of scientifically robust on-farm research trials every year. “The data will allow scientists and engineers to use the latest advances in super-computing and quantitative modeling to advance understanding of nitrogen and develop tools that the public can use to forecast best management practices and improve efficiency,” Castellano said. “Our science will generate continuous improvement in resource use efficiency that benefits society on and off the farm.”
Supporting the best science for nitrogen management is just one of the ways Trammo is encouraging the transition to a greener planet.
Alyssa Ehrich, Iowa State University Foundation, 515-357-9198, firstname.lastname@example.org