Emily Heaton | Assistant Professor of Agronomy, Iowa State University
Are wet spots hot spots for nutrient loss? That is the question Steven Hall will be addressing in the ILF Webinar Oct. 17, and it is one that interests me greatly. What I really want to know is, if wet spots are hot spots, what can we do to cool them off? And boy with all the precipitation, 2018 was a great year to test these questions!
Fig. 1 Steve Schomberg has miscanthus planted on a few hundred acres near Letts, IA. Miscanthus is being used to replace coal for heat and power on the UI campus. Miscanthus’ deep root system and abundant soil residue allows harvesting when bare soil is too wet for equipment. Photo credit: Emily Heaton
Steven is part of a team of researchers, extension specialists, farmers, and farm groups digging into the economic and environmental performance of farmed potholes. As Iowa State University’s Extension Biomass Crop Specialist, I help this team learn if we can improve profit alongside water and nutrient cycling by incorporating perennial biomass crops into farmed potholes.
So, what are biomass crops?
Biomass crops are those harvested for their whole above-ground biomass, not just grain or fruit. The only perennial biomass crops widely grown in Iowa today are forages such as (give examples), but that could change as plants are increasingly used to replace things we get from petroleum today. For example, the University of Iowa is replacing coal in their power plant with the perennial grass miscanthus (Miscanthus x giganteus), grown on ~2,500 acres in the Iowa City area (Fig. 1). The UI expects miscanthus to provide about 10% of the entire university’s heat and power load within the next few years.
As those of us rooted in the prairie Midwest know, perennials have deep root systems that hold soil and clean water. They also require less fertilizer and fossil fuels to thrive and only have to be planted one time! Because of this, their carbon footprint can be considerably lower than the annual crops we currently use for energy, like corn ethanol and soy biodiesel, and there is growing demand for them. Perennials also tend to be more resilient than annuals, including tolerating drought and flood stress that would kill an annual (Fig. 2).
Fig. 2. Looking north (top) and south (bottom) at a farmed pothole on the ISU Sorenson farm July 3, 2018 (left) and Oct. 12, 2018 (right). The pothole flooded multiple crops (from top left in top photo: cool-season grass CRP, miscanthus, corn, miscanthus, soybeans, sorghum) multiple times this year. The soybeans and later the corn, were a complete loss. The perennial CRP survived and miscanthus thrived, due largely to growth habits and established roots. Photo credit: Emily Heaton and Nicholas Boersma.
With all this in mind, our team is asking the following questions:
– Could we get feedstock for low-carbon fuels and products by planting crops like miscanthus in farmed potholes?
– Can farmers make more money with a resilient perennial in potholes instead of corn/soy?
– Would planting perennials in potholes change the amount and quality of water leaving farm fields?
We are hoping to find the answer to these questions, and discover new questions to ask, in several experimental plots we’ve established near the ISU campus (Fig. 3) as parts of a USDA NIFA grant and a Dept. of Energy grant. We will be monitoring ponding depth, water quality, greenhouse gas emissions and crop growth in experiments with separated and controlled tile drainage systems (white lines in top left of Fig. 3) as well as in “natural” farmed potholes (red outlines). In both cases we will test both corn/soy and miscanthus, along with the annual crop sorghum, which seems more resilient to environmental stress than corn.
Fig. 3. New ISU experiments will assess perennial and annual crop impacts on potholes using controlled drainage experiments (top left; white lines are tile maps) and monitored potholes (bottom right, red lines are ponding outlines) near Ames, Iowa.
To learn more about this exciting research, listen to Steven’s webinar on Wednesday. I know Steve will welcome your questions or insights into what we are doing. And then, in a year or so, once the sites are really established and we have data to share, we will be having public field days. Keep your eyes on this blog to know when and where!