Harvesting corn stover

Craig Sheaffer, Extension Agronomist; John Lamb, Nutrient Management Extension Specialist (Emeritus) and Carl Rosen, Extension Soil Scientist

Harvesting corn stover. Photo: C Sheaffer

Corn stover remaining in the field following grain harvest is a valuable resource providing significant benefits to soil conservation and soil health. In addition, the nutrients in incorporated corn stover are recycled and used by the following crop. Harvest of corn stover for livestock feed or bedding reduces its beneficial effects on soil.

Soil conservation

Stover left on the soil surface or partially incorporated provides residue that can reduce soil erosion by wind and water. Incorporation of stover improves soil health by increasing soil carbon and tilth, water infiltration. Of course, the impacts of corn stover on these attributes is dependent on the amount of stover produced and left on the field. Because corn grain and stover yields are related (typically a 1:1 ratio), as grain yields increase so does stover production. In our research over several locations in Minnesota, we found the corn stover production ranged from 3.2 to 4.0 tons/acre and on average 3.8 ton/acre. An average of 0.8 ton/acre of corn cobs were produced (Tables 1 and 2). However, because of differences in cropping systems, tillage, soil erosion potential, and harvest methods, farmers typically only harvest a part of the stover residue. Minnesota Extension provides a decision support tool for deciding the amount of corn residue to harvest for various crop rotations, tillage systems and yield levels.

For more information, see Predicting soil loss with RUSLE2 (Penn State) and Crop residue management.

Table 1. Quantities of grain and stover, nitrogen (N), potash (K₂O), phosphate (P₂O₅), and sulfur (S), with stover when corn was harvested at the agronomically optimum N rate at four locations.*

Location	Grain	Stover	N	K20	P2O5	S
	bu/acre	T/acre	lb/acre	lb/acre	lb/acre	lb/acre
Becker	210	4.0	46	158	9.2	4.1
Hastings	243	3.5	42	105	8.2	3.3
Lamberton	160	3.7	50	49	4.1	3.2
Red Lake Falls	164	3.2	57	56	6.2	3.8
Mean	194	3.8	48	92	6.9	3.6
lb/ton			13	24	1.8	0.9

*Results are averaged for two years at each location. For experimental details, see Sindelar et al., 2012 and 2013. Becker and Hastings were irrigated sites while the others were rainfed.

Table 2. Quantities of grain, cob, nitrogen (N), potash (K₂O), phosphate (P₂O₅), and sulfur (S), removed with cob when corn was harvested at the agronomically optimum N rate at four locations.*

Location	Cob	Stover	N	K20	P2O5	S
	bu/acre	T/acre	lb/acre	lb/acre	lb/acre	lb/acre
Becker	210	0.8	6.8	9.2	1.0	0.4
Hastings	243	0.8	6.4	11.6	0.9	0.4
Lamberton	160	0.6	5.3	10.2	0.7	0.4
Red Lake Falls	164	0.8	6.8	8.6	0.7	0.4
Mean	194	0.8	6.3	9.9	0.8	0.4

*Results are averaged for two years at each location. For experimental details see Sindelar et al., 2012.

Livestock feed and bedding

Corn stover is used as livestock feed and bedding. Corn stover is low in nutritive value. It contains about 5% crude protein, 70% NDF concentration, and 50% dry matter digestibility. It is often used in maintenance rations of non-lactating beef cows. Supplementation with energy and protein are required if corn stover is the primary ingredient in rations for growing and lactating animals. 

Grazing is a cost-effective on-site approach to stover utilization and cattle can be more selective and eat the higher quality leaves and grain lost in combining. (Felix, 2023). Grazing livestock also deposits manure nutrients as they move over the field and through hoof traffic increases decay of stover. Baled corn stover is often lower in quality than grazed stover because of field harvesting losses which include chopping, shredding, and raking. Dried corn stover can be used as livestock bedding and will absorb 2.5 times its weight in water compared to 2.1 for wheat straw.

For more information, see Grazing corn stalks with beef cattle.   

Corn stover nutrients

An economic consequence of corn stover removal is the loss of plant nutrients. In our research, we found an average of 13, 24, 1.8, and 0.9 lb of N, K₂O, P₂O₅, and S removed per ton of stover. At a retail price of $0.60, 0.30 and 0.30, and 0.50 per lb of, N P₂O₅, and K₂O, and S, respectively, the value of nutrient removal in 3.8 tons of stover per acre would be $61 or $16 per ton. However, there was considerable range in nutrient content of stover, and we found that increasing N fertilization rate increased N, K2O and S removal.

Stover removal will result in an accelerated depletion of soil nutrients beyond those nutrients removed by grain harvest. Soil analysis following corn stover removal is recommended to provide location specific fertilizer recommendations as nutrient returns by corn stover are affected by stover yield and harvest losses. There was significantly less removed by only cob removal and if a cob harvest system is used, nutrient removal would be less.

What about cellulosic ethanol?

There was considerable national interest in cellulosic ethanol production from corn stover following the passage of the Energy Independence and Security Act and development of the Federal Renewable Fuel Standards in 2007. An initial goal was to produce 16 billion gallons of cellulosic ethanol by 2022. This led to construction of several large-scale process ethanol production plants in the Midwest with potential to produce about 130 gal of ethanol per ton of corn stover. In our research, ethanol yields from corn stover ranged from 303 to 410 gal/acre.

However, there are no ethanol producing plants operational today and it does not appear that a viable cellulosic ethanol industry will develop. This development is related to several factors. These include the challenges of conversion of cellulosic energy to ethanol and as well as variation in quality of product due to contamination with soil. Also, unlike corn grain, which is the primary feedstock for ethanol production, corn stover is bulky and challenging to transport and store.

Acknowledgement

Research on corn grain, stover and cob nutrient composition and conversion to ethanol was funded by the Minnesota Corn Growers Research and Promotion Council.

References for this publication

D. Kramer. 2022. Whatever happened to cellulosic ethanol? Physics Today 75: 22–24. https://doi.org/10.1063/PT.3.5036

T. Felix, 2023. Penn State Extension. Grazing corn stalks with beef cattle. https://extension.psu.edu/grazing-corn-stalks-with-beef-cattle

J. DeJong-Hughes and J. Coulter. Crop residue management. Minnesota Extension. https://extension.umn.edu/corn-harvest/crop-residue-management

C. Wortmann, R. Klein, and C. Shapiro. 2012. Harvesting crop residues, Nebraska Extension. https://extensionpubs.unl.edu/publication/g1846/pdf/view/g1846-2012.pdf

W. Edwards. 2020, Estimating a value for corn stover. Iowa State Extension. https://www.extension.iastate.edu/agdm/crops/pdf/a1-70.pdf

A. Sindelar, J. Lamb, C. Sheaffer, H. Jung, and C. Rosen. 2012. Response of corn grain, cellulosic biomass, and ethanol yield to nitrogen fertilization. Agron. J. 104: 363-366. https://doi.org/10.2134/agronj2011.0279

A. Sindelar, J. Lamb, C. Sheaffer, C. Rosen and H.G. Jung. 2013. Fertilizer rate effects on nutrient removal by corn stover and cobs. Agron. J. 105:43-445. https://doi.org/10.2134/agronj2012.0240

J. Hartschuh. 2019. What are your bedding options? Ohio State Extension.
https://u.osu.edu/sheep/2019/04/23/bedding-options/