Opportunities expand as farmers discover new uses for corn stover 

By Dan Quinn, Purdue Extension Corn Specialist And Bruno Scheffer, Purdue agronomy Graduate Research Assistant 

As the renewable energy and bioproducts industries continue to grow, Indiana corn farmers are being presented with new opportunities for uses and selling opportunities beyond just the grain, but also the stover (e.g., the leaves, stalks, and cobs that remain after harvest). Corn stover has shown to be a promising feedstock for bioenergy, bioplastics, and other emerging technologies. 

Furthermore, Indiana alone produced roughly 30 million tons of corn stover in 2024 and as corn yields continue to increase. The total amount of dry stover produced each year also continues to increase. For many farmers, the prospect of selling stover is an attractive one. 

However, certain questions arrive with stover removal and include: 

• What essential plant nutrients am I losing with removal? 

• How will this affect soil nutrient levels, soil organic matter, and long-term soil quality and health? 

That’s because stover isn’t just leftover plant matter, it also contains essential macro and micronutrients which can be recycled back to the soil for the succeeding crops grown. In addition, leaving stover behind also protects against erosion, helps retain moisture, builds soil organic matter, and contributes to long-term carbon storage. 

Overall, removing too much can deplete essential nutrients, reduce fertility, reduce soil quality, and force increased dependence on synthetic fertilizers. 

Previous articles and research have found that corn stover baling, while potentially profitable, comes with a cost, which includes nutrient loss (Camberato, 2008). Stover contains valuable crop nutrients that would otherwise be recycled back into the soil. 

Essential macronutrients like phosphorus (P) and potassium (K) are lost with every ton removed and these nutrients should be figured into the economic equation of removing stover from your field. 

For example, previous research has found that on average, every ton of stover contains about 3.6 pounds of P₂O₅ and 20 pounds of K₂O. Therefore, a 150 bushel per acre corn crop has been shown to leave behind about 4 tons of dry stover per acre. 

If roughly 60 percent is baled (about 2.5 tons per acre) you’re removing around 9 pounds of P₂O₅ and 50 pounds of K₂O (Camberato, 2008). Furthermore, other key nutrients such as nitrogen, calcium, magnesium, sulfur, and micronutrients also exit the field with stover removal, which can be especially concerning in low-fertility soils or under long-term removal scenarios. 

Corn stover nutrient removal 

Beginning in 2024, research funded by the Indiana Corn Marketing Council (ICMC) in collaboration with Purdue University and FiberX sought to re-examine corn stover nutrient removal amounts and soil nutrient level and quality impacts over time with different rates of stover removal. 

As corn grain yields continue to increase and as corn genetics and physiological traits continue to change, it is important to reassess dry stover totals, quality and the impacts of stover removal in current productions systems. This is also important as new markets and companies begin to provide new opportunities for stover use. 

This research trial was established following corn harvest in 2024 at two diverse Indiana locations: Purdue University’s Agronomy Center for Research and Education (ACRE) in West Lafayette, Ind., and the Southeast Purdue Agricultural Center (SEPAC) in Butlerville, Ind. 

The research trial was designed to examine different stover removal rates (0-100 percent) across different corn yield levels and hybrid types. For example, this research trial examined dry stover amounts and nutrient composition of the new short-stature corn hybrids (PR112 and PR116) in comparison to a typical full-stature hybrid (DKC62-70). 

Yields and dry stover production 

Preliminary results indicate a clear linear relationship between corn grain yield and total dry stover production per acre, as expected (Figure 1). These findings align with previous research which has shown an approximate 1:1 ratio between pounds of grain and pounds of dry stover produced per acre. 

For instance, at the ACRE location, corn yields ranging from 280 to 300 bushels per acre corresponded to roughly 7 tons of dry stover per acre. However, slight differences among hybrids were observed. In addition, the hybrids evaluated exhibited harvest indexes (grain-to-stover ratio) near 0.6, indicating that grain production slightly exceeded stover production in most cases. 

The study also assessed the nutritional composition of the stover, comparing both full- and short-stature hybrids (Table 1). Both hybrid types showed similar concentrations of nitrogen (N), phosphorus (P) and sulfur (S), while potassium (K) levels were slightly higher in the short-stature hybrids. 

On average, nutrient concentrations in the stover were 0.82 percent N, 0.12 percent P, 0.72 percent K and 0.06 percent S for the full-stature hybrid, and 0.81 percent N, 0.12 percent P, 0.79 percent K and 0.06 percent S for the short-stature hybrid. 

Declines in soil organic matter 

This research trial re-examines dry corn stover totals, nutrient concentrations and nutrient removal rates in relation to current yield levels and both existing and emerging corn hybrid types. Findings highlight that when stover is harvested and removed from the field, essential plant nutrients are also removed from the field and must be accounted for in nutrient management plans and profitability calculations. 

Additionally, stover removal can lead to declines in soil organic matter, increased soil erosion and compaction due to machinery use. As such, it is important to quantify these impacts over time and to better understand the trade-offs of stover removal and balancing the potential for additional revenue with the need to maintain soil fertility, health and long-term productivity. 

This research is ongoing and will be expanded and repeated in 2025 and beyond to refine results and assess long-term soil impacts.