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Technicians Calvin Vick (left) and John Massey
measure switchgrass stem density and geometry
at the upstream end of a riparian gully at Little
Topashaw Creek in Mississippi.
The object of this question is intended to be the grass not the man. If it were the latter the quick joke would be "because he can't pronounce Miscanthus." Otherwise the answer is that someone told him to mention it, which is of course the answer, but why? Why has switchgrass (Panicum virgatum) been nominated as the most promising lignocellulosic energy crop and is it really our savior?
Following a decade of exploring the potential of trees, sugar crops, and aquatic plants as biofuel feedstocks, the US Department of Energy initiated the Herbaceous Energy Crops Program in 1984. The candidate species met several of the criteria discussed previously namely; production practices familiar to farmers, potential to sequester carbon below ground, and low demand for inputs when grown on relatively poor land. Eighteen perennial grasses or mixtures were tested over six years in seven states (Virginia, Alabama, Ohio, New York, Indiana, Iowa, and North Dakota). The top recommendation across the board was indeed switchgrass and sorghum and sorghum x sudangrass, two species with an annual growth habit, showed a great deal of promise as well.
While the study really did pick a winner, it was not comprehensive. After all, Miscanthus was never tested and recent results suggest that in some environments in the US, it will yield considerably more than switchgrass. Therefore, the job of vetting potential energy crop candidates is incomplete. The screening projects only examined a relatively small number of species in a handful of potential growing environments. Other species under consideration today include cordgrass, Jose tall wheatgrass, and giant reed.
More individual species need to be rigorously evaluated, which should include examination of invasiveness. For example, the potential of giant reed to yield biomass must be balanced with (among other things) the ability to control it as a weed if it escapes cultivated areas. Secondly, species mixtures must be given greater consideration. While cultivating monocultures of traditional crops has its advantages such as uniform maturity and harvestability the disadvantages including genetic susceptibility have proven all too apparent.
A partially harvested field of sorghum near College Station,
Texas August 29, 2007. New towering types of sorghum are
being developed by Ceres and the Texas Agricultural Experiment
Station for next generation biofuels made from inedible plant
stems, stalks and leaves.
Fortunately, forage is often cultivated as mixtures of several species, grasses and legumes, and thus the breeding, business, and farming practices are in place for negative carbon energy crop mixture production where increasing the number of species (diversity!) increases yield.
So should we expect a horizon of waves of switchgrass? It is not what we should hope for and it is not very likely. Additional species will appear on the horizon as well, some more gradual than others. One certain to make a quick splash on the scene is sorghum, pictured left. It is an already established high yielding and all around hardy plant with several market classes: food, forage, and now fuel. We should shoot for a diverse landscape of energy crops, which will require further exploration of candidate species.
Comments
Whether switchgrass or sorghum, biofuel cultivation will always remain somewhat suspect to me. The high volume of output required for extensive fuel processing, and the fact that these crops will not end up on the dinner tables of humans, suggests to me that they will tend to be cultivated in a manner that is ecologically deleterious. Past production endeavors for biofuels have often resulted in agricultural practices that deplete the topsoil and pollute through the overuse of fertilizers and pesticides (See: The Great Biofuel Hoax of 2008.
Posted by: Tim | July 27, 2008 5:34 PM
Tim: without wanting to cheer on corn ethanol, or dumb farm subsidies, or over-industrialized farming ...
I just want to understand the implications of your plan for, say Iowa:
1) Which doesn't really have much in the way of oil, gas or coal.
2) And hence has to import petroleum fuel to run the farms, at least right now.
3) Whose population density is low enough that hybrid cars aren't quite as useful as they are in urban areas.
4) Which has wind, but is not the best place for solar.
5) And which primarily uses rainfed agriculture, not California-style irrigation.
Take a look at my July 17 & 18th posts over at Climate Progress, for example.
This is what Iowa looks like. The mean farm size is 350 acres.
What do Iowa farmers do as petroleum gets really expensive?
Do they:
1) Go bankrupt?
2) Dump their not-yet-paid-off $200K combines?
(A typical combine is 300-400HP, with a 60-gallon diesel fuel tank. I don't know offhand how to electrify that yet. I'd happily hear about prototypes.)
3) Go to organic vegetable farming in place of grain?
[minor issue: farm labor needed. This is *not* a knock on localized farming, and I love veggies. I'd just like to see a plan that says that's what Iowa would do.]
4) Split each 350-acre farm into 5 70-acre pieces and sell them to old order Amish, who will use horses.
5) Electrify what they can, and grow biofuel crops whose prices track petroleum prices.
6) or something else?
SUMMARY:
1900: 40% of US population lived on farms
2000: ~2%
Suppose we go back to less-industrialized farming (some of which will happen, given Peak Gas and fertilizer), and the farming population rises back to 10%-20%, will you be happy to be one of the 8-18% of the new farmers working smaller farms without any kind of fuel?
I must ask the same sort of questions I always ask:
Can you describe your live experience with real working farms and farm economics? Especially in the mid-West or any approximation thereof? Have you lived on a farm or in a farm community?
Posted by: John Mashey | July 27, 2008 9:34 PM
... suggests to me that they will tend to be cultivated in a manner that is ecologically deleterious.
I do not share your sentiment. Continuous corn cropping has been shown to have a deleterious effect on the soil. Ergo, your argument that "if it's not going to be on the dinner table, it's going to result in bad land management" is way off.
Posted by: TomJoe | July 28, 2008 9:31 AM
TomJoe;
Farmers know that about corn, that is why they rotate: corn,wheat,beans and then fallow.
Posted by: Jim | July 28, 2008 5:12 PM
Jim,
I'm aware of it. I was responding to Tim's comment that because switchgrass and the like are not food crops, they are more prone to be cultivated in a manner that will lead to abuse of the land. However, that's not stopping farmers in the "Corn Belt" from switching to continuous corn (which is a food crop) thanks to the ethanol boom. I was providing a counter to his argument.
Rather than being worried about what crop is being grown, I'd be more concerned with the fact that the land is being bought up by non-farmers who are looking at the land as simply a profit-making venture. They're less apt (IMO) to be concerned with the longterm effects of certain cropping methods. Also, when a farmer rents the land (which is happening more and more often), they're less likely (once again, IMO based on anecdotal evidence) to give a hoot as to how they're farming.
Posted by: TomJoe | July 28, 2008 6:14 PM