Water experiments study today’s rainfall, ponds and streams near Cuba at the Greater Chicago Metropolitan Water Reclamation District (MWRD) research site. But the University of Illinois researchers and their partners also anticipate changes in the availability of water for agriculture.
Current and future water needs were discussed at the Nutrient Management Field Day on Tuesday at the Fulton County MWRD site.
Richard Cooke, a professor at the University of the Island in agricultural and biological engineering, is studying other uses of existing tile systems to provide water to parched crops as well as to drain saturated fields. “Recently there have been concerns about subirrigation and the need for it,” Cooke said.
Cooke pointed out that rainfall patterns are expected to bring more intense spring rains, requiring drainage and dry summers when subirrigation will be needed for profitable corn production. “What can we do to move forward? How can we anticipate? We have to try,” the engineer said.
“With subirrigation, you have to provide water, and we want to look at the economics,” Cooke said. “We are looking for ways to feed and pump the water.”
Cooke is investigating low-cost power sources to pump water through drainpipes for subirrigation. Neither system would require electricity or fuel, although each has advantages and disadvantages.
Cooke showed solar panels that power the pumping system on the ground. Although suitable for most field locations, solar panels do not work on overcast days or at night.
In an adjacent creek, a spiral water pump relied on the flow of the stream to provide power. The waterwheel system was capable of lifting water 52 feet and operates 24/7 with flow, Cooke noted.
MWRD Commissioner Eira Corral Sepulveda listened to Cooke and his fellow researchers discuss the capture and reuse of resources and nutrients. “What you do here today can really shape the future,” she told them.
“The MWRD is taking on the challenge of removing phosphorus and managing the economics of it,” Sepulveda told FarmWeek. “Phosphorus is a finite resource. What we discover today in these experiments will impact the future of agriculture.
Capture and recycling
To capture nitrogen and phosphorus in water drained through pipes, Wei Zheng, a researcher at the Illinois Center for Sustainable Technology, is studying a system that combines a bioreactor with a chamber filled with biochar.
Biochar is a charcoal-like product produced by pyrolysis (high temperature anaerobic heating) of biomass. At the MWRD research site, Zheng is testing granulated biochar that does not break down quickly. He demonstrated by dropping a few pellets into a bottle of water, watching a few bubbles escape as the pellets remained intact.
In field trials, 12 acres of subsurface drainage passes through three differently designed bioreactor and biochar systems. Nitrogen is removed in bioreactors while phosphorus and ammonium are trapped in biochar, Zheng explained.
“We can significantly remove nitrate with bioreactors. With biochar, we want to reuse the nutrient and apply it in the field to reuse phosphorus” as a slow-release fertilizer, Zheng said. He estimated that biochar can capture between 50% and 70% of phosphorus in subsurface drainage.
The biochar in the chambers should be changed at least once a year, according to Zheng. Rooms at the Fulton County site are changed in December. “We plan to change (the biochar) maybe every six months or year-round,” he added.