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Study Raises Concerns Over Amount of Corn Stover Biomass Available for Cellulosic Ethanol

Researchers at the USDA-ARS have concluded that the corn stover needed to maintain soil organic carbon, and thus productivity, are a greater constraint to environmentally sustainable cellulosic feedstock harvest than that the use of stover to control water and wind erosion.

Wally Wilhelm, USDA-ARS scientist with the Agroecosystems Management Research Unit, Lincoln, NE, and his team compared the amount of stover needed to replenish soil organic matter and control water and wind erosion under a limited number of production conditions—continuous corn and corn produced in rotation with soybean with moldboard plow or conservation tillage practices.

The amount of stover needed to replenish soil organic matter was greater than that required to control either water or wind erosion in the ten counties (in nine of the top eleven corn production states in the US) investigated. This outcome emphasizes the need to further evaluate the validity of widely circulated estimates of US cropland capacity to sustainably supply feedstock for the emerging cellulosic ethanol industry. The study in published in the Agronomy Journal.

Corn stover, the above-ground material left in fields after corn grain harvest, has been identified as a primary feedstock for the production of cellulosic ethanol. Stover and other crop biomass or residue is frequently referred to as trash or a waste, implying it has minimal value. However, when returned to the land, this carbon-rich material helps control erosion, replenishes soil organic matter, and improves soil quality.

Organic matter in the soil retains and recycles nutrients and improves soil structure, aeration, and water exchange characteristics. In addition, organic matter is the energy source for the soil ecosystem.

Most estimates of the amount of crop residue that can be sustainably harvested consider only erosion as a constraining factor, without considering the need to maintain soil organic matter. Recently Jane Johnson and her coworkers at the USDA-ARS North Central Soil Conservation Research Laboratory at Morris, MN, reported estimates of the minimum biomass input needed to maintain soil organic matter (5.25–12.50 Mg ha–1).

The authors conclude that there is a critical need to gather additional high-quality replicated field data from multiple locations to confirm their calculations and to expand the computations to a broader range of cropping systems before major decisions are made about the percent of stover that can designated for biomass energy production. In addition, they state that an extensive effort is needed to expand development of existing crops, discover and develop unconventional crops, and create and deploy advanced cropping systems that exploit the potential of all crops so that biomass production can be greatly expand to provide a sustainable supply of cellulosic feedstock without reducing soil organic matter, thus undermining the productive capacity of the soil.

The article is available for 30 days free access at the Agronomy Journal website. Agronomy Journal is a peer-reviewed, international journal of agronomy published six times a year by the American Society of Agronomy.




Yes, keep the reports coming. Eventually people may finally realize that any sort of corn based ethanol production is a joke.
Cellulosic feedstock has to be indeed TRUE waste, like garbage in a landfill. Not half the fertilizer for next year's fuel, or the food for a million people...

Jim G.

I heard about a plan to spread tge use of relatively low tech low cost pyrolysis machines in the developing world. From what I gather, a farmer would distill waste to produce a biogas to sell and use the charcoal as fertilizer, replenishing soil carbon and not loading it into the air. Perhaps this offers a better model for Americans as well.


PoetEnergy has solved this problem of soil erosion when removing cellulose for ethanol production by only using the corn cobs and not the entire corn stover.


Harvey D


Your point is well taken. Whatever is used to produce corn based cellulosic ethanol will have to be replaced to avoid accellerated soil depletion and erosion and maintain an appropriate balance.

Fortunatly, there are many other (non-food) feed stocks to produce cellulosic agrofuel. Are they really less damaging on the long term? Comparative studies and trials are required to establish sustainability and long term environmental effects.


This really isn't anything new, despite what they say. I've heard about SOC levels and corn stover removal for quite a while now. And while the numbers vary from study to study, all of them say that it is possible to remove a good chunk of the stover under good conditions. Even this study suggests that 30-50% of the stover can be removed under no-till situations. And if you include planting a winter cover crop (which this study did not consider), that number can be increased even higher.

POET's solution is only the simplest. We should still be able to get respectable yields of ethanol from corn stover without harming the soil as long as the farmers are adapting their practices to increase the amount of cellulose they can harvest.


why not use the waste ligin from the cellulosic ethanol plants to help replenish the carbon?


Context people, Context. I doubt seriously if any farmer would intentionally do damage to thier fields. If the farmer can get more for the corn stover than he pays for an alternative soil ammender. Then we will have corn stover ethenol, if not we won't.

"warning" A mass extiction asteriod will hit the Earth.

Useful ain't it


We still have the 50 million acres of switch grass production that the government pays farmers to grow to prevent soil erosion. Maybe it could be mowed for the cellulose, while leaving the root system in place to prevent erosion.

John Baldwin

This is a better approach.

Make biogas from waste, from anything that used to be living, put it in the gas grid


Then run CNG vehicles on it, made by VW etc



Switchgrass and Mistanthus are both perennial grasses, which means their root systems go deep enough to hold soil nutrients and water. We will be able to use a certain amount of stover for cellulosic feedstocks without impacting soil health, but there are more viable alternatives available.


It would be worthwhile to perform further tests tests on soil carbon content with the conversion of part of the stover to charcoal (with the gas used for energy) and returned to the soil.


John Baldwin,

biogas is nice and all but biomass waste can only replace ~15% of petroleum, plus the conversion for cars and fuel transport is more intensive and expensive then ethanol. Best if biogas just goes into the NG mains to replace NG, which despite the hype for will peak within 10 years of oil.

How sustainable are switchgrass or miscanthus? How many times can you mow it down before it gets sparse? Especially if it grows on marginal land, it seems like that will be a challenge. I read about somebody that takes waste biomass from a pyrolisis and buries what basically looks like a charcoal briquette dipped in some fertilizer and says it helps soil fertility for decades...dunno.



That would be pyrolysis oil and biochar/agrichar, which also has some strong potential, both as carbon sequestration and keeping the soil in good shape.

tom deplume

I still think the best use of biomass to energy is simply burning the stuff as boiler fuel for a powerplant. No new bioengineered bugs or tricky catalysts needed. Just a collection and distribution system needs to be organised.


"Cellulosic feedstock has to be indeed TRUE waste, like garbage in a landfill. Not half the fertilizer for next year's fuel, or the food for a million people..."

Which is why we should wring our hands and accept the inevitable apocalypse. The END is near!


The problem with burning cellulose as boiler fuel is the low efficiency; we simply cannot grow enough to continue our lifestyle that way.  However, there appear to be options with far greater efficiency (e.g. direct-carbon fuel cells) which appear to make the problem tractable.


Pure nonsense. Haven't these "researchers" heard of covercrops? Dead biomass offers nothing compared to living biomass that maintains real living soils.


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