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Stover Collection Aids Soil Management

By Staff | Jun 14, 2011

After the first seasons of corn stover baling for Project Liberty, officials of POET Biorefining have received positive news from their research partners. Studies on the effects of removing corn stover from fields have shown no negative impacts on farmland.

The announcement comes following studies of POET’s contracted biomass removal rates with area farmers, and determined that the rates are both conservative and consistent with good soil management, according to updated site data gathered by Iowa State University and USDA researchers.

Researchers from Iowa State University have completed analysis on data from the third year of an ongoing study for POET near Emmetsburg to monitor how soil health is affected when crop residue is removed. POET’s planned 25 million-gallon-per-year cellulosic ethanol plant, “Project LIBERTY” will use corn cobs, leaves, husks and some stalk to produce ethanol.

The newest data confirms previous assertions that removing about one bone-dry ton per acre, which is about 25 percent of the area’s above-ground crop residue, will not cause significant nutrient loss. In fact, corn yields continued to show no yield loss or moderate increases in fields with this rate of biomass removal.

“Based on this study, we conclude that one and a half to two tons per acre of corn stover can safely be harvested from fields similar to those used in the study,” according to the research summary prepared by Dr. Douglas L. Karlen with USDA-Agricultural Research Service and Dr. Stuart Birrell with Iowa State University. The study went on to note that appropriate removal rates will vary depending on how productive the soil is in a specific area.

The research data also showed no significant difference in soil carbon after three years. That research will continue as well, including an analysis of deep core samples.

POET is committed to a conservative approach to biomass harvesting, Project LIBERTY Director Jim Sturdevant said. “The data is our guide, as it should be for everyone looking at this new feedstock. We’re contracting for fewer tons per acre to ensure good soil management even in years when yields are lower. Also, our farmers have moved away from traditional methods of stover removal: of chopping, raking, baling and leaving the field black.”

Farmers harvesting for POET typically turn off the chopper on their combines and leave windrows behind during grain harvest. Farmers do not rake the biomass before the baler gathers it. Last fall, in 2010, 85 farmers harvested 56,000 tons of biomass, and they are almost finished delivering it to Project LIBERTY’s 22-acre stackyard on the south side of the Emmetsburg POET Biorefinery complex. Those farmers are also developing conservation plans with the help of Natural Resources Conservation Service (NRCS).

Once operational, POET’s Project Liberty plant will use approximately 300,000 tons of biomass annually. Construction on the cellulosic facility is planned to begin later this year.

Dr. Karlen and Dr. Birrell will continue their work again this year. They stressed that farmers “know their land” and say routine soil testing and plant analysis are good practices for monitoring nutrients as part of good farm management.

“We’re committed to working with researchers and farmers to make sure this is done correctly, and it looks like that is the case right now,” POET Chief Executive Ofiicer Jeff Broin said. “There is no model to follow in putting together a system to produce cellulosic ethanol, but we’re committed to creating that model for the long-term benefit of the country.”

Broin continued, “Renewable fuel requires healthy soil, We’re glad to be working with quality research partners to ensure the soil around Emmetsburg remains that way.”

Based on the three years of data gathered at the site, the researchers recommend farmers replace about 15 additional pounds of potassium per acre to fields where biomass harvesting has occurred at a rate similar to what POET contracts. No significant increase for nitrogen or phosphorus replacement compared to grain-only harvest is needed.

Removal of biomass also demonstrated no grain yield losses and offered moderate grain yield improvements over the control plots. One theory to explain that phenomenon is that removing a small amount of cover helps the soil warm earlier in the spring, causing earlier corn plant emergence.

“We’ll continue to monitor the soil through our on-going partnership with Iowa State and USDA, and we’ll share that data with farmers,” Sturdevant said. “We’ve learned a lot from the first three years of data and from the feedback from farmers. Results have been positive, but we’re trying to be conservative as we keep learning.”

“This is exciting,” Sturdevant added. We’re bringing a new way to produce ethanol to America.”

A research summary provided by Dr. Karlen and Dr. Birrell and a slideshow recap of the learning processs for farmers during 2010 biomass harvest are available at POET’s website. Photos of fields after biomass harvesting are also available for viewing.

POET, the largest ethanol producer in the world, is a leader in biorefining through its efficient, vertically integrated approach to production. The 23-year-old company produces more than 1.7 billion gallons of ethanol and 10 billion pounds of high-protein animal feed annually from 27 production facilities nationwide. POET also operates a pilot-scale cellulosic ethanol plant, which uses corn cobs, leaves, husks and some stalk as feedstock, and will commercialize the process in Emmetsburg, Iowa. For more information, visit www.poet.com.