Research highlights new ways to recycle nutrients and support soil health
Crop residue can serve as a valuable source of recycled nutrients, helping farmers improve soil health, reduce costs, and support future crop productivity through effective residue management. This farmer advice from Ava Isaacs, a first-year PhD student at the University of Illinois working in the crop physiology lab with professors Fred Below, PhD and Connor Sible, PhD, of the University of Illinois.
Crop residue has become both a challenge and an opportunity for farmers as crop yields continue to increase. Researchers and agronomists are finding new ways to turn leftover stalks and leaves into valuable nutrients that can improve soil health and support future crop growth.
Studies at the University of Illinois research plots are focusing on how farmers can better manage the growing volume of crop residue produced after harvesting. Modern corn hybrids and higher plant populations have significantly increased yields over the past several decades. However, these gains have also created larger amounts of residue that growers must manage each year.
Researchers explain that every bushel of harvested corn produces a considerable amount of plant material. This residue contains important nutrients, including nitrogen, phosphorus, and potassium, which can be returned to the soil and used by future crops. Instead of viewing residue as waste, scientists are investigating ways to recycle these nutrients more effectively.
“For every bushel an acre that we get in yield, we have 44 or more pounds of dry residue coming out of the back of the combine, and that’s a lot to manage. So, we’re trying to convert, capture and create — degrade residue to convert it into a usable form, capture those nutrients we’re getting from the residue and create yield from that residue degradation,” said Isaacs.
She added, “There’s a lot of nutrients that are locked away in the residue. We’re looking at 20 pounds of nitrogen, 4 pounds of P₂O₅ and then 23 pounds of K₂O locked away per ton of residue. So if you’re dealing with five and a half tons of residue from your 230-bushel an acre crop, that’s a lot of nutrients you could be using in the next year.”
According to research findings, crop residue can hold substantial amounts of plant nutrients. If residue breaks down efficiently, many of those nutrients can become available for future crops, potentially reducing fertilizer requirements and improving nutrient use efficiency.
Farmers have traditionally relied on tillage or chemical treatments to help manage residue. While these approaches can be effective, rising fuel and fertilizer costs are encouraging growers to explore new alternatives. Biological products are gaining attention because they can help accelerate residue decomposition while fitting into existing field operations.
Researchers note that biological applications can often be added during routine herbicide or burndown passes, reducing the need for additional trips across the field. This can save time, lower fuel use, and improve overall operational efficiency.
Agronomists say biological tools may also help improve the natural breakdown of crop residue during the fall and winter months. Faster decomposition can release nutrients back into the soil and create a healthier environment for upcoming crops.
Field observations suggest that biological residue management can contribute to improved soil structure and increased organic matter. As residue decomposes, nutrients are gradually released into the root zone, where developing crops can access them more easily.
Agronomists also report that recycling nutrients through residue management can provide economic benefits. Instead of relying solely on purchased fertilizer, growers may be able to recover nutrients that were already absorbed by previous crops. This approach can help maximize the value of every acre while supporting long-term sustainability.
“We’ve created really hard, really healthy plants to digest. We started worrying about and managing trash in 2005. Our answer at the time was to use a cheap source of AMS and just add more nitrogen to the system. I used to attack this problem by putting an extra 50, 60 units of nitrogen out into the system. Back when we started that program, it was 17 cents a unit of nitrogen," said Robert Phillips, a field agronomist with Integrated Seed Solutions, Flanagan, Ill.
He added, "Now we’re talking $1.17 a unit of nitrogen. It’s not economical and not sustainable to be just dumping that much nitrogen into the system and burning through carbon faster. With Carbon Cycle, we’re creating more humus, more stable carbon for the other biology to feed on and it’s really increasing the soil health.”
Soil health remains a major focus of current research. Healthy soils can improve water infiltration, support beneficial microbial activity, and enhance crop resilience during challenging growing conditions. Researchers believe effective residue management can play an important role in achieving these outcomes.
Long-term use of biological products has also been associated with improvements in soil microbial activity. Some field observations indicate reductions in certain soil-borne disease pressures, although continued research is needed to better understand these effects.
As production costs continue to fluctuate, many growers are searching for practical ways to maintain profitability. Nutrient recycling and residue management practices offer an opportunity to capture value from materials already present in the field.
Researchers emphasize that crop residue should not be viewed solely as a harvest byproduct. When managed properly, it can become part of a natural nutrient cycle that supports crop productivity, soil health, and farm sustainability. Continued research will help farmers identify the most effective strategies for turning residue into a valuable resource for future growing seasons.
Photo Credit: University of Illinois