9UNP0139SD Phil Robertson_WordPress

- I'd like to thank you all for coming. My name is Tim Donahue. And again I'd like to thank you for coming to a special seminar that's sponsored by the Great Lakes Bioenergy Research Center. For those of you who don't know what the Great Lakes Bioenergy Research Center is, it's a new DoE funded research center, housed at the UW-Madison, but functioning as a virtual center across the country to help develop and rollout technologies for the conversion of cellulosic biomass into fuels. One critical part of that center's activity is the topic of today's lecture, in particular, in addition to work going on in the center on the improvement of plants, and microbes and chemical activities to make it easier to convert plant biomass into fuels, there are significant activities in the center worrying about the days when we take those observations from the lab bench out into the field. And that's under the broad brush of our sustainability activities. So there's been a lot of legitimate discussion in the free press lately about how biofuel activities can and will be sustainable in the future. And so it is very timely that several months ago, Phil Robinson, who's the leader of the sustainability program in the GLBRC agreed to come over and visit with people at Madison and give a talk on those aspects of the program. As I said, Phil is the leader of those activities. 

And he's the perfect person in our mind to do that. He's a professor of Ecosystem Science in the Department of Crop and Soil Science at Michigan State University. And he's been there since 1981. Since 1998, he's directed the Long-term Ecological Research Program in Agricultural Ecology at the Kellogg Biological Station, the experiment station in the state of Michigan. So he brings to the center and to the table in this activity, a large and productive and internationally-known research program, in thinking about and dealing with issues related to sustainability. So with that, I will shut up and introduce Phil. I thank him for coming today. 
(applause)
 
- Well thanks, Tim, and thanks everyone for showing up this morning. 

It's a pleasure to be here. And it always amazes me that I'll be talking about a topic that wasn't on most of our radar screens only two years ago. And it's a fun topic to talk about in many respects, partly because it's controversial. But more importantly, because it integrates a lot of what we know about agricultural ecosystems in a way that helps to inform the sustainability of these systems, and perhaps the birth of a new agricultural industry across the U.S. and across the world. Well, let me start by explaining a little bit about why I phrased my talk this morning this particular way. That is, the "Biogeochemical Challenge." There are, of course, a lot of different aspects to the sustainability of biofuel cropping systems and cropping systems in general. We have to think about economic sustainability, profitability of these systems. If they're not profitable, of course, they're not going to be sustained. We have to think about the environmental sustainability of which biogeochemistry is a part. 

We have to think about the social sustainability of these systems, the potential for these systems to contribute to rural development and the sustenance of rural communities. And, of course, we have to think about food security. A part of this has been in the press a lot in the past few weeks and causing some people to doubt the overall sustainability of biofuels in general, for good reason. And I'll talk about that a little bit. We're considering all aspects of sustainability in the GLBRC, but I want to focus on biogeochemistry in the main part of my talk today. First, because if we can't get this part right, then biofuels lose a lot of their attraction. We're in this business, apart from the issues of energy security, we're in this business for an environmental standpoint, largely because of their potential for helping to stabilize climate. So climate stabilization with respect to CO2 content of the atmosphere is a biogeochemical issue. And second, while the biochemistry is not complex, there are aspects of it that are quite simple, in fact, there are a lot of pieces that have to be understood if we're really to design sustainable systems, and to get the most out of these systems in the future. So I think it's important for all of us to understand at least most of those pieces. 

So as you'll see, we're not talking simply about carbon balance, we're talking about other greenhouse gases and perhaps some other co-benefits, some biochemical co-benefits of these systems as well, on nitrogen cycling, for example, and the potential for cellulosic systems to ameliorate some of the nitrate issues and some of the nitrous oxide issues that we now face with agriculture as it's done today. And I'll talk in detail about the biogeochemical needs then in relation to our ongoing research effort. And then I'll describe, I'll take a few minutes at the end, actually more than just a few minutes, to describe the overall sustainability research that we anticipate will be a major part of the GLBRC in the years to come. It's a major part now, but the GLBRC as many of you know, is just getting started. So much of this research is still in its very nascent part. From the outset, the promise of biofuels is a win-win situation for a lot of reasons. It's a win-win situation from the standpoint of farmers in many respects. It's a win-win situation from the standpoint of the environment in many respects. It's a win win situation from the standpoint of some key social issues, as well, for society, I would argue. But that really is the case only if it's done right. 

There are a lot of opportunities for doing it wrong. We need to be aware of those pit falls from the outset. And that's one of the reasons that we're extremely pleased to be part of the GLBRC from the outset to try to anticipate some of these problems as cellulosic biofuels become a major part of the biofuel economy in the years to come. So it might be helpful to start at the top and close to first principles, simply because given the controversial nature of what we're about, and I have colleagues on both sides of the various disputes that have arisen, in some cases yelling at each other in print. It could be useful to think for a moment about what we're trying to achieve with this. And at one level, what we're trying to do is to reduce the flow of petroleum into the economy to a trickle. You're not going to be able to read the pieces on this, I'm not so much interested in that, as you're seeing the size of the arrows. This is a description, a DoE description of energy flow for the most recent year available, or petroleum flow for the most recent year available, 2006. And we have on the order of 15 million barrels a day coming into the U.S. economy. Around 10 million barrels that are coming in as imports, and the remainder as produced here. 

And I'm not going to take you through all of these pieces, the important part is this bit down here, these 14 million barrels of transportation fuel, which translates to about nine million barrels of gasoline. And it's that that we're trying to reduce to a trickle from a societal standpoint. We want to reduce this fat arrow here, which is the biggest petroleum user in the economy to something akin to what electric power is currently using. So the EPA released a couple of months ago an analysis, a wedge analysis of the transportation sector petroleum use. And a wedge analysis is simply a way of taking Steve and Bob's wedges for stabilizing climate at some background level, 2006, in this case. What technologies would need to be brought to bear to keep CO2 concentrations in the atmosphere at levels that are 2006 levels. And this is specifically for the transportation part of the CO2 burden in the atmosphere. And the EPA divided this stabilization triangle into nine different wedges. It's just a way of approaching the issue of asking what different technologies can contribute, how much to solving the stabilization problem. And the wedges that they identified, that would be potentially available, and needed to stabilize 2050 CO2 levels in the atmosphere at 2006 levels are these listed here. 

And the values here are the size of the wedges that are needed. And so, gasoline hybrids are expected to contribute somewhere on the order of .8 to 1.0 wedges to the solution, which requires nine wedges. Plug-in hybrids, 1 to 2. You can read down here all the various technologies that are thought to be necessary to bring us to this point. The biofuels plays a role in this. And a role in all other different scenarios that EPA presented. And the thinking is that biofuels can provide somewhere on the order of 1.3 to 2.7, depending on the scenarios that are presented. Wedges to contribute to a total of six to 13 wedges, which would be enough to stabilize the transport sector's contribution to CO2 stabilization at 2006 levels. And this 1.3 to 2.7 translates to about 40-80 billion gallons of ethanol per year. So that's one analysis of the target we're heading for, is that amount of quantity of fuel. 

Now this taken by itself, I wouldn't necessarily believe the EPA's analysis without some additional support. And the NRDC, it turns out, did a similar sort of analysis, a year or so ago, and came to basically the same conclusion. That is, by 2050, if we can divide the total transportation, expected transportation needs in terms of today's million barrels of oil. So something on the order of 17 million barrels of oil per day, projected to be needed by 2050, some portion of that, a large portion of that, we ought to be able to achieve with efficiency and smart growth policies and behaviors. But some portion of it is going to still be, we're still going to be reliant on liquid transportation fuel. That liquid transportation fuel could be biofuel. Some part is still going to be gasoline. There's no issue there. But they came to a similar number, somewhere on the order of 80 billion gallons of ethanol that's needed. So there's a considerable legislative momentum starting to set the trajectory for this as well, as I'm sure most of us are aware. 

In December, the U.S. passed the U.S. Energy Policy Act of 2007, which aims to produce 22% of transportation fuel mix in 2022, which means 36 billion gallons of ethanol that's projected to be available in only 14 years, which is not very far from now. And 21 billion gallons of that is expected to be, by target, cellulosic ethanol. And 15 billion gallons of grain-based ethanol. The EU is close behind. The EU recently set a target of 20% renewable energy by 2020. And 10% of that, or half of that target, is targeted to be transport fuel. So there's also a big push in Europe for the quick development of these fuels. We're pretty close to the capacity that was already identified by the Energy Security Act, which currently, we have a capacity in the U.S. of about 13.5 billion gallons. So we call that, we're talking about 80 billion gallons or 60 billion gallons as a total need. And if 15 billion gallons targeted for 2022, we're just about there for grain alcohol. 

So we're effectively, I won't say maxed out, but we're very rapidly getting there, more rapidly than many of us would like. But in any case, just to put in perspective where we are versus where we're aiming to get as a society, as the legislative society, we're well on our way to developing this economy. So the next question is how much biomass is needed to satisfy this quantity of ethanol. If we take as a target a midpoint of the EPA range, some 60 billion gallons, we're looking at a need for grain biomass using today's technology that translates to about 2.6 gallons of ethanol per bushel of corn. We're look at about somewhere around the order of 23 billion bushels of corn needed to satisfy that demand. And you can compare that to 13 billion bushels of corn that were produced in 2007. If you look at future technology, this is a fairly mature technology. In the near future, it's likely to produce only an increase of around 10%, up to 3 gallons per bushel, mainly due to higher starch varieties coming into the processing stream and grain cellulose conversion. We're likely to see a need for somewhere on the order of 20 times ten to the ninth bushels, which is still well over the capacity of the U.S. corn market to satisfy. So, clearly there are limits to what we can do with grain ethanol. 

And we have to turn to cellulose ethanol. And we then have to ask, well, how much biomass do you need for cellulosic ethanol. And again, we can look at today's technology where pilot plants are producing on the order of .3 liters of ethanol per kilogram of biomass. And it's an easy calculation to make. Figure out, well, how many kilograms of biomass does one need to produce that much ethanol. And it comes out to somewhere around 776 million metric tons of biomass. Well that's a big number. What do you do with that number? How do you compare that number to what is available? Well, one way to think about that is to think about all of the corn stover that is produced in the U.S., which is an easy number to calculate, because there's about the same mass of stover produced in above ground residue in a corn field as is produced in grain. 

And so, we know that based on the overall yields of corn, actually this is an analysis that covered the period, 1995-2000, that around 196 million metric tons of corn stover were produced and Graham, and others, who produced this analysis also suggested that about half of that, about 110 metric tons, could be removed in a sustainable manner. That is, if these corn fields were grown under a no-till situation, so that some proportion of the litter was left in place, not harvested, in order to protect against erosion, and in order to provide enough biomass for carbon sequestration, then we're probably thinking about more on the order of 110 times ten to the sixth metric tons that could be sustainably removed. We could also think about the amount of biomass that's available from industrial waste, both from the pulp industry, as well as from the wood products industry. Material that is readily harvested, simply because it's in an industrial setting in point source in effect already. And so it would be fairly easy to pull together and put into the stream. So we can think about needing 776 million metric tons of biomass for today's technology. And it's likely that we will get some improvement in that technology-based on GLBRC research in large part, so that we might be looking at something on the order of .43-liters of biomass yield in the future, which would bring us to the need for 530 metric tons of biomass. So the stover and the wood waste are low hanging fruit. Those are readily available now in today's technology without harming the productivity of the current cropping systems. I'm not suggesting that if we moved to a continuous corn system that would be a way to satisfy part of that need, but just with existing technology, existing economies, this is a kind of biomass that we could divert now to a cellulosic biomass stream. 

So taking these numbers then, you can ask, well how much land is necessary to satisfy this. And if we subtract off the low hanging fruit, then we can come up with 560 million metric tons needed for today's technology, 314 for tomorrow's technology. And we can think about how many millions of hectors are needed to bring into production to do that. But if we take switch grass at today's yields, and these are realistic field-based yields, not experiment station yields, somewhere around 7.5 metric tons per hector, then we can easily calculate that we need somewhere around 75 million hectors of land, on which to grow switch grass in order to satisfy 100% of this ethanol need. Some time in the future, we might be able to increase that yield, we might be able to get away with only 42 million hectors. If we were to use human grasslands, native prairie perhaps, then we would need, which has lower productivity than a switch grass system, we would need somewhere on the order of 112 with today's technology, and somewhere on the order of half of that with future technology. So the basic answer here is we need somewhere between 40 and 100 million hectors of land on which to put this technology. Well how much is that? It's a lot, because if you consider that we only have 180 million hectors of land currently cropped in the U.S., we're not going to divert a large portion of that to cellulosic biofuel production without having severe impact on food security. We also have, however, a large number of grasslands. 

Some of those are arid range lands, but a fair proportion of it is grasslands that are classified as grasslands, because they're not currently used as production. They're marginal land, perhaps former farmland that has been abandoned and is now in landscapes as successional systems. We also on the order of 15 million hectors of CRP land, which could be harvested if the rules were changed and added to the stream. And so we have this need for somewhere on the order of 40-100 million hectors of land. It could be satisfied if we think about land that, especially land that is not currently used for food. And that's one of the promises, I think, of a cellulosic bioenergy economy, as opposed to the current grain-based economy, which by definition, as we all know from recent spikes in grain prices certainly, has a big impact on food production. So there's another aspect of this, too, and that is that we also have a fair proportion of abandoned agricultural land, especially in the Great Lakes region, which I'm sure that any of you, and certainly in Michigan, driving across the Michigan landscape, there's an awful lot of marginal land that was taken out of agriculture in the past, and has been reverted to successional systems on the order of anywhere from recently abandoned to 50-100 years old at this point. And that land could also be reconverted. As far as I know, I'm not aware, at least of any comprehensive analysis of the availability of those lands. But at least an analysis that was done over the period of 1982-1997 showed that there was somewhere on the order of 12 million hectors of land that had reverted from cropland to forest. 

And forest is defined as 10% cover, so in Michigan, it takes about 20 years for a 10% cover of trees to come into an abandoned agricultural field, so this is, I think, a big underestimate of what's actually available and could be converted to cellulosic crops, perhaps to native systems, perhaps to planted switch grass, perhaps to a variety of cellulosic feed stocks that we'll have to think about as we think about these issues. So the problem, of course, with grain ethanol is that as we think about the impacts of ethanol, in a sense, it's simply business as usual but larger, with all of the attendant environmental problems that are associated with today's agriculture, ranging from growth hypoxia to various pesticides that enter waterways, to impacts on the trace gas content of the atmosphere, and biodiversity issues. So there are also some huge sustainability issues that most of us recognize with respect to grain ethanol, that may not be the case, should not be the case with cellulosic systems. So cellulosic systems we have the opportunity to add perennially to U.S. cropping systems in a much bigger way than we currently have. So the perenniality simply meaning planting crops that are not tilled every year, not planted every year, not nurtured every year in the same way that annual crops are, and so we have the potential to install these grasslands or woody crops in places that are now farmed marginally, and that can provide a lot of benefits that we're not now seeing. Those benefits including those that come from landscape diversity, such as effects on insects, beneficial insects in particular, effects on water quality, effects on wildlife and effects on climate stabilization. And that's what I'm going to talk about in much of this next portion of the talk-- what is the role of agriculture in adding to the mitigation portfolio for global strategies? So I want to take a big picture here first, and then I'll zero in on some research that we've been undertaking for the past 20 years, or so, at the biological station. But to set the stage, I need to talk first about-- This is a graph that everyone is familiar with. It shows the long-term rise of atmospheric CO2 and our game plan, ultimately, is to keep CO2 levels stabilized at somewhere in this range here, with this projected 2100 range at the midpoint, IPCC scenario, one of the conservative scenarios, showing that where the trajectory is to be way outside of those bounds. 

So in order to keep current levels stabilized, whatever current level we're at the time that stabilization is effective, it requires thinking about the global CO2 balance. So if we think about the contemporary global CO2 budget, we can categorize different sinks and sources as are done here. So we have sources as being emissions from fossil fuel, emissions from deforestation, as the two principle sources of CO2 to the atmosphere. So we have somewhere on the order of 9.1 pentagrams of CO2 being added to the atmosphere, CO2 carbon, being added to the atmosphere annually. That carbon is being removed from the atmosphere at a rate of 2.2 pentagrams, by ocean, mainly by chemical processes in the ocean, and 2.8 pentagrams being taken up by terrestrial vegetation and soils, and staying in the terrestrial vegetation and soils, which leaves a difference of 4.1 pentagrams, that is the atmospheric loading rate for CO2 in the atmosphere. And when we think about stabilizing CO2, what we need to think about is how do we bring this term to zero, so that we're not longer adding CO2 to the atmosphere that stays there. We'll be adding CO2 to the atmosphere, of course, but we'll expect that CO2 to be removed from the atmosphere on an annual basis, so that stabilization ultimately results in this term, the atmospheric increase going to zero. As you can see, we're going the wrong direction at this point. Just in the past decade, we've increased this term by over 25%. No surprise. 

So what is agriculture's role in all of this? Well, agriculture has several roles to play. If you classify the strategies for stabilizing atmospheric CO2 into three broad strategies, we can think about reducing fossil fuel consumption by improving efficiency, by developing renewable energy sources, such as biofuels, we can think about identifying CO2 sinks and sequestration rates. And, of course, many geologists think it's possible to store CO2 in geologic reservoirs, perhaps in aquatic reservoirs. But the more practical sequestration that's certainly is possible now, or that agriculture can help with is that sequestration of carbon that was lost at some point in the past, into soils and into long-lived plants. And then the third major strategy is reducing the non-CO2 greenhouse gases. There are other greenhouse gases other than CO2 that are in the atmosphere that are biogenetic, that are naturally occurring, and that agriculture, as I'll show in a few minutes plays a huge role in regulating. So let's think about carbon loss and the basis for sequestration in ag systems. And the potential for carbon sequestration in agriculture basically stems from the loss of carbon when agricultural lands were initially converted. The exact same processes that are going now when we clear tropical rain forests. 

We lose carbon from soils, and we lose carbon from the trees and above-ground vegetation. And that occurs universally, across the globe, at a rate of about 40-60% is lost over 40-60 years. This is known from the 1950s. It seems to be one of these rules of thumb that doesn't diverge much no matter where you are. It's possible to calculate. There is some 54 pentagrams from an original 220, or so, pentagrams that was lost in this way. So that means that there's a potential for recovering that carbon and taking it out of the atmosphere and storing it in soil, if we can develop the technology to do that. And the no-till technology is, of course, one of those main strategies. And the calculations, the conservative calculations, is that we can remove somewhere on the order of .3 to .5 pentagrams of carbon per year. Somewhere around 10% of the current carbon loading rate in the atmosphere is possible to, as a mitigating contribution from the development of soils that store more carbon. 

But there's a 54 pentagram cap. That is, we're not going to be able to recover more than was originally lost, and probably we're only going to be able to recover some proportion of that, maybe 50% of that. Eventually this soil saturates. That saturation occurs somewhere on the order of 50-100 years after the technology is implemented. Now CO2 is not the whole story, of course. We also have these other gases. The other biogenic gases, those gases that are produced by microorganisms in soil in native, as well as managed ecosystems, include nitrous oxide and methane. And those are also adding to the radiative forcing to the atmosphere. Those also offer an opportunity to stabilize the radiative gases in the atmosphere. Those two gases in particular, methane and nitrous oxide, are also increasing exponentially now, as is CO2. 

This is a 2,000 year history, mainly from ice forests for carbon dioxide, which is in red here, and you can see that the methane, which is in blue, as well as the nitrous oxide, which is in black, are both tracking the same sort of trend. Now why are those interesting? Those are trace gas that are in quantities in the atmosphere that are a fraction of those quantities that are represented by CO2, but they have an interesting feature. They have a much greater impact on a molecule by molecule basis than does CO2. So the global warming potential, which is an atmospheric chemist's way of comparing the radiative impact of a molecule of any gas against some reference gas is much higher for methane and nitrous oxide than it is for CO2. So by definition, the global warming potential of CO2 is one. The usual IPCC way of calculating the impact of these is over a 100-year time horizon. These have different atmospheric lifetimes, so you have to consider the amount of time you're making this impact estimate. Methane has 23 times the impact of CO2. Nitrous oxide has 300 times the impact of CO2. 

So what that means is that avoiding the emission of one kilogram of nitrous oxide into the atmosphere is equivalent to avoiding the emission of 300 kilograms of CO2. So avoiding a little bit of nitrous oxide has a big impact on the CO2, or I should say the CO2 equivalent burden of the atmosphere. So if you think about where nitrous oxide or methane come from and how they get into the atmosphere, we can define that the major anthropic sources of these gases are agriculture. And in the case of methane, about 55% of the methane that is currently produced by humans is from agricultural activities, and about 45% from industry. Nitrous oxide, about 80% comes from agriculture and a much smaller percentage from industry. That becomes interesting when you total up in carbon equivalents what the total impact of these are. It's possible to calculate then that there's somewhere on the order of 3.2 pentagrams of carbon equivalents being emitted to the atmosphere from human activities, a large part of this is agricultural, which suggests that agriculture could play a strong role in mitigating the buildup of these radiative gases with the proper management. And it gives us the opportunity then to think about the CO2 budget of cropping systems, not just in terms of energy balance, as is more common in bioenergy systems, but also in terms of the total CO2 equivalent accounting, which includes these other gases, as well as carbon. And so, we can think about sources of global warming potential and a cropping system that's not just the carbon balance, not just carbon sequestration into the soil or carbon decomposing and releasing its CO2 in a bio-refinery, or once it's burned in a vehicle, but also the other greenhouse gases that are involved. It allows us to count that as a benefit, if you will, on that side of the ledger. 

So what are the major sources of global warming impact and fuel crop ecosystems? There's fuel use, of course, that's a no brainer. There's also soil carbon change, which is the basis for carbon sequestration. There's also nitrogen fertilizer. Nitrogen fertilizer takes a fair amount of energy to produce. It takes, in fact, a fair amount of methane to produce. And the process of producing by the Haber-Bosch process releases CO2. So there's a CO2 cost for nitrogen fertilizer that's a burden on the ecosystem's carbon balance. There's also a lime. The agricultural lime that we add to cropping systems is a carbonate, and that carbonate, as it's attacked by acid over the course of the cropping season, turns into CO2. 

So there's another source of CO2 in the system. And then, of course, there's also nitrous oxide flux and the methane flux. So I want to use as an example some research that we've been conducting at KBS over the past 20 years and bring you up. Some of you may have seen some of this before, most of you, I'm sure haven't. But I want to present some updated data. We had, in place, at KBS as part of the LTER site there, a series of cropping systems that are arranged along a management intensity gradient, ranging from annual grain crops, which we would consider high intensity, through perennial biomass crops, which would be the equivalent of the cellulosic biofuel system. Through unmanaged communities, including an early successional old field, which is simply a field that we let go in 1988 when the plots were established. And so while it's not native prairie per se, about 50% of the species are exotics. The native plants are plants are grown in an unmanaged setting. And we also have midsuccessional old field, a field that was abandoned 50 or 60 years ago, and then an old growth forest. 

We have some postage stamp-sized wood lots that have never been cut, so allow us to use these for reference points for what was probably the pre-European settlement fluxes for these gases. So we can think about soil carbon change over the first ten years of this experiment. As you would expect, there was no gain of carbon in the annual conventionally tilled system, and some 30 grams per meter squared per year was gained in the no-till, which is actually the median rate at which carbon is sequestered in no-till systems. But the interesting piece here is that the poplar and alfalfa systems both sequestered carbon as well. Which makes good sense, simply because they're also no-till, right? You plant these things and you don't go back and till them every year. They're also adding woody roots to the system that the herbaceous systems are not, so we might expect them to be at least in some cases, to add more to the soil carbon sequestration rate. But more interesting is this early successional system, which is adding almost twice as much carbon to the soil than is either of the other perennial biomass systems and twice as much as a no-till system. And here is a probably an effect of diversity, that is we have more diverse plant material coming into the system, and the microbes are having a tougher time of breaking it down on annual basis. Now here we have an example of the saturation of this, in that the sequestration goes from 60 in the first ten years down to somewhere less than 11, or so, in the midpart of the century. 

And then it goes to zero in the old growth forests. Old growth forests are by definition at equilibrium. Their carbon balance is not changing much. As a result, we have no sequestration potential in a like successional forest. We can expect soil carbon sequestration to disappear after about 100 years of whatever kind of perennial crop we're putting in without tillage. I want to talk about the nitrous oxide portion of this for a couple of minutes as well. And nitrous oxide is measured in a very simple minded way. It's very labor intensive. There are no better ways to do this at this point, but it simply is a matter of putting a box on the soil surface and collecting the gases that are emitted by that soil over the next 30 minutes to two hours, and then plotting a flux based on the concentration change in that box over that one to two hour period. When you do this, and we've had the luxury of being able to do this for almost 20 years now. 

I think we have the longest continuous record of N2O fluxes from cropping systems now in the world. But when we do this, we see that there are very strong patterns, and that the annual cropping systems are producing N2O at equivalent rate that are about three to four times the rates in the unmanaged systems. So even the reference system in the native forest, which is slightly higher than the early and mid-successional systems have rates that are on the order of a 1/3 to 1/4 of those that are in the annual cropping systems. Perennial crops are different, based on whether nitrogen is available. Alfalfa, which is a legume, has N2O fluxes that are equivalent to those from the annual cropping systems, which makes sense if you think about what are the major controls on nitrous oxide production. This is a bacterial process called de-nitrification that results in the microbes producing N2O from nitrate. There's a lot of nitrate circulating in these systems. So there's a lot of available substrate for the denitrifying bacteria. Poplars on the other hand are extremely efficient from a nitrogen utilization stand point. You would expect it, therefore you might predict that nitrous oxide fluxes would be low. 

In fact, they're even lower than they are in the unmanaged systems, which suggests that there's a real potential for a cellulosic perennial biomass crop to provide this service to a landscape in which it's planted. That is, to avoid the emission of nitrous oxide, as opposed to a crop that was there prior to it's being grown. Early successional system is similar to a prairie system, if you will. It also has very low nitrous oxide fluxes that aren't much different than the poplars. Now CH4 oxidation, and this is a process whereby methane is taken out of the atmosphere and -- by methanatrophs in soil, about another class of bacteria that in this case use methane as an energy source. Methane oxidation is interesting globally because about 30 terograms of methane per year are removed from the atmosphere by soils. And that removal occurs mainly in undisturbed ecosystems, mainly in forests. It turns out that when you convert these native systems to agricultural use, you effectively shut off methane oxidation. And that is important globally, because of the atmospheric burden of methane in the atmosphere. We're adding about 44 terograms per year from all sources. 

Soils are taking out 30 terograms. So if soils were not taking out 30 terograms, we would have an atmospheric burden that would be 44 plus 30. And so the soils are responsible for keeping the atmospheric concentration of methane at a much lower level than it would be otherwise. Now what are we doing to it though? We're shutting it off with conventional agriculture. So we're asking the question, is there a potential for cropping systems to be managed somewhat differently, perhaps cellulosic crops could play a role in this to produce a soil microbial community that would be good at pulling methane out of the atmosphere. And we see that there isn't much here that suggests that we have that capacity with most cropping systems. And it's not until we enter our midsuccessional system, native vegetation, 50 or 60 years old, that we start to get significant recovery of that methane oxidation. So there is a potential for using cellulosic crops to also lessen the methane burden. Okay, so how do you put this together in a total system context at the field scale in any case, to ask what are the different potentials across these different cropping systems for doing this mitigation. 

It's possible to build tables. I'm going to go quickly through five or six similar tables here, and build a table that has all of these systems in it. But I want to spend just a minute talking about the first entry so you'll be able to track better the next set of numbers. So in a conventionally tilled system, a corn, soybean, wheat rotation, there's no change in soil carbon, so there's no soil carbon contribution. There is no contribution to either mitigation or the CO2 burden in atmosphere from soil carbon changes in a conventionally tilled system. There's about 27 grams of CO2 equivalent per meter squared per year added to accountable to that system based on the nitrogen fertilizer that's applied. About the equivalent amount based on the agricultural lime that's applied. This is over a ten year period, actually over 20 year periods now. There's a fuel cost of around 16 grams of CO2. And there's an N2O cost of around 52. 

And a net mitigation, a net credit for CH4 oxidation. There's a little bit going on, but that gives us a total value of around 100 units of CO2 equivalents being produced by this system. So far it's at equilibrium. There's no annual change and nitrous oxide is the largest source of CO2e in this system. So if we switch to a no-till system, we can reduce this net increase, this net contribution of cropping systems to radiative forcing in the atmosphere by almost 100 units, based almost entirely on the soil carbon sequestration. And we count this as a negative, because it's pulling carbon out of the atmosphere and storing it in soil. There's a little bit of savings on fuel because no-till systems use a little bit less fuel. But importantly, there's no differences in nitrous oxide. The organic system has a net somewhere in between the no-till and the conventional, largely because we're getting a little bit of soil carbon sequestration, which is a surprise, for other reasons. But we have no inputs from fertilizer or lime. 

But interestingly, the same burden of nitrous oxide as I showed in the earlier bar graph. Now the perennial biomass crops change this to a more favorable mitigation scenario, where we're actually getting mitigation in this case, as a net effect. So the alfalfa is sequestering a lot of soil carbon, no doubt because it's perennial and the roots are in the system and decomposing in place. They're not replanted each year. No nitrogen fertilizer. We are adding a fair amount of lime to counteract acidity. Only a little bit of fuel compared to the annual crop existence, but again the same amount of N2O leading to some mitigation. The poplar trees bring this to a very substantial net mitigation potential in these systems. Minus 105, so we've got almost a 200 gram CO2 per meter squared difference between the poplars and the conventional tillage system. So that tells us that we're on the right track here with providing some mitigation services that are not available in the annual grain systems. 

And again, it's partly because of the no-till or restoring in carbon. But also notice in here, we've cut down the N2O burden by almost a factor of six. The successional communities are the ones that really provide the most power for net mitigation here, with almost a minus 200 twice out of the poplar. So this is effectively a native prairie. You could also think of this as a perennial grass. That is, there's no reason to think functionally that this shouldn't be any different from a C3, C4 grass mixture, or even a complete single species mixture. That's one of the questions we're investigating in the center is, does it matter that this is a mixed species community versus a monoculture switch grass community. Switch grass is a native prairie grass, but just planting a single species, may have some effects, as well as some risks, that we wouldn't see in a mixed system. But importantly here, the net effect drops off, as you might predict, because of the soil carbon sequestration to some midpoint here. And it disappears entirely by the time you redevelop the late successional forest. 

Okay, so it's possible to reconstruct a graph that looks something like this for a total. These are effectively the cellulosic biomass crops. These three systems here in the middle. The alfalfa, the poplar and the early successional systems. So quite apart from any benefit that is obtained from substituting the carbon from these systems for fossil fuel in the fuel mix, there's this other aspect to their carbon economy that needs to be kept in mind as we think about what's the best design for these cropping systems in the future. There is also a co-benefit. And this is one of the interesting, and I think very potentially valuable aspects to these cellulosic systems, as well, and that is because these systems are perennial, they have roots in the ground the whole year. They're growing the whole year, in effect, whenever the temperatures are above a certain point, there's still photosynthesis going on, which means that there's still the potential for nitrogen uptake, which means that any nitrate that might be in the soil, that might otherwise wash through the system, would be available for plant uptake. And in fact, we see that. This is nitrate leaching over an 11-year period, where we've had monitors in the ground beneath these crops, pulling nitrate out and measuring the water flux by modeling, and showing that conventional systems are leaching somewhere on the order of 500 kilograms of nitrate over this period per hector. 

But the cellulosic systems are very low. In the case of the poplars, we can't detect any leaching under the poplars. We don't have the data yet for the native systems. This is a paper that's just now being assembled. So there's this other benefit that might also accrue from building a landscape that includes not just annual crops, but also some mixture of perennial crops that will provide services that we're not getting now with these almost monoculture and biculture landscapes. And that's what we're aiming for. We're aiming to design these systems. So I want to take five or six minutes to just to review what we're doing in the GLBRC with respect to sustainability. And some of this ties into what I've been talking about, but others of it is quite different. So our overall objective is to support the biomass and bioenergy pipeline by developing practices that are economically viable and environmentally responsible. 

And we're particularly interested in carbon neutrality and greenhouse gas mitigation, and also in quantifying the ecosystem services that could be provided by biofuel landscapes. Now the way we're approaching this is from a hierarchy of levels. At the first level, we're looking at the development of novel production systems. That is production systems based on crops that now exist, or that will be developed as part of the GLBRC activities in other research areas. So eventually, we'll be having additional crops to think about then, this wheat that we have now or improved varieties of this wheat that we have now, that we'll be able to enter it into the system. But we have two aspects to production goals. One of them is defining what are the novel production systems that will be the most productive, that will provide the suite of services that we want to encourage from these systems. We can also think about what are the improved microplant interactions that might lead to the improved performance of these novel systems. All of these systems have environmental responses and economic responses. The environmental responses are the biogeochemical responses that I've already described through the statisticians at KBS, nitrogen and carbon cycling in particular. 

There are also biodiversity responses. That is what is the response of an insect community, or a microbial community to 20 years of switch grass or 20 years of poplar, versus 20 years of corn soybean rotation. So there's going to be some responses there that will be important to quantify. Then, of course, there are economic responses also, as the economy of these systems will be very different depending upon a whole host of attributes. So we'll take these responses and use them to inform models at different geographic scales to eventually provide us with information on what are the potential farm and landscape designs that we could put out into these future agricultural landscapes, and think about what are the regional and national impacts of these designs. And that will help to inform us as to what sort of additional changes we need to make to the production systems in order to tweak the outcomes. And eventually, it should provide us the information needed to design the optimal configuration of landscapes, who, as Pete Nowak was speaking to me this morning about, how do we paint these landscapes in a way that optimizes the ecosystem services that can be provided by these systems. So a quick word about the approach we're taking to examine all of these processes. As we've arranged a series of ecosystems and series of cropping systems along a gradient of high input low diversity, to low input high diversity. With one end of the spectrum being continuous corn, mainly for grain, but also for the total biomass of the crop to a restored prairie, at the other end of the spectrum. 

But also a number of other systems, including poplars, early successional switch grass systems, as well as a more environmentally benign-- It's not benign, but a more environmentally responsible system than continuous corn. And then within each of these different portions of the project, each of those different circles that I had up on the previous slide were examining specific hypotheses. And I'm not going to read through all of these, but rather just quickly summarize that. With any improved microbial plant interactions program, we're looking at both organismic level, as well as genomic level responses to improving the plant, improving the ability of plants to take up nitrogen, to be more nitrogen efficient, for example, or perhaps even more carbon sequestering by manipulating the microbial community in that system. Biogeochemical responses are not just looking at the carbon cycle, but also water use and nutrient loss, as I've already eluded to. Biodiversity responses are looking at several targets, including microbial biodiversity, but from the standpoint of what we see, thinking also about predatory and parasitic insects and their control in landscapes. Bees, which provide pollination services, of course. Game and song birds, as well as the microbes. And all of these provide very quantifiable, and in some respects, ecosystem services. And part of our challenge in the economic portion of this is to quantify those ecosystem services in ways that can inform policy a bit better than they're currently being informed. 

And so in the economic arena, we're interested in thinking about crop area change forecast and the implications of that for the landscapes that we're going to be seeing, so that if we build scenarios in which we favor grain based alcohol, for example, that's going to have a very different effect on land change, than one in which we build policies that incentivize cellulosic landscapes. We'll be able to look at that in terms of ecosystem service valuation, in particular. And then, the modeling component is at several different scales. The objective is to build a framework that allows us to run scenarios to forecast, what are the outcomes of these different policy decisions, these different behavioral decisions that we're making as a society, and how that will effect, eventually, the CO2 concentration in the atmosphere. That runs from the modeling. This is my last slide. The modeling runs from the site level, where we're using biophysical models to predict carbon and nitrogen and plant growth. All the way through landscape, regional, national and global levels, where we're using integrated assessment models to ask what does putting this much cellulosic biofuel into the landscape, what effect does that have on climate stabilization on CO2 stabilization, knowing what we know about land use change, about population growth, about technology innovation and about climate change during that period, and so on. So the integrated assessment models are those models that are used to build the IPCC scenarios that predict CO2 concentrations over the next century. And we have a group involved in the center, who has built these IPCC models, and will be using those models to predict the eventual outcome. 

So I'm going to stop there and would be happy to take questions in whatever time is available. I just want to summarize very briefly by the comment that what we're talking about with cellulosic systems is very different from what we have now with our current generation of ethanol plants. In that, we're not talking about continuing the business as usual grain ethanol production, but we're trying to shift the discussion and shift the potential scientific understanding of the outcomes to the cellulosic arena, because they're vastly different. The environmental impact of cellulosic systems in the future are just orders of magnitude different than they are for grain-based alcohol production systems, which, to a very large extent, are business as usual. Yes, we can make improvements to those systems. You saw that in the conventional systems that I had up there, in fact, the no-till system was better, the organic system had specific attributes that were good. So the low input could improve those. But none of them send those systems to net mitigation. The only systems that send them to net mitigation are mainly the systems that are perennial and produce above-ground biomass, as opposed to seeds. So I'll stop there. 

Thank you very much. 
(applause)
 
- Thank you, Phil. We do have time for questions. But the other thing I'll say before I forget to say it later, is we have some treats and goodies outside afterwards to give people some more time to meet each other and to talk to Phil or anyone else who's here. So questions for Phil. And I need to run around. 
- Thanks for the very interesting talk. You've got a slide in there that showed that emissions from deforestation are actually declining and, of course, we've been reading Science Magazine about concerns about that with biofuel. 

And then, some of your other charts with your early successional forests, I mean, it seems like we might want to minimize carbon, actually manage some of our forests for early succession. And what you hear from a lot of folks is we need old growth. What are some of your thoughts on that? And what are the next steps to getting from the corn economy to the biomass economy, in your eyes? 
- Your last question is the hardest, of course, and I don't know if I'll be able to address that effectively. But it's one that we need to think about addressing effectively. Your first question about the deforestation adding less CO2 to the atmosphere now than it did in the 1990s. I was also surprised by that. It doesn't take into account the additional deforestation that's currently happening because of higher food prices. This is a 2000-2006 period of analysis. 

It was published in PNAS last year. My expectation is that when we do the total 2000-2010 budget, that it will probably show the same or an increase, because of the clearing that's now happening, because, in particular, because of the oil palm clearing that's going on in Indonesia. We have peat soils being exposed to oxidation with their very large carbon contents, because they're being cleared for the oil palm production. So I wouldn't put a lot of stock in that small decrease in deforestation at this point. The issue with respect to the successional vegetation. You know, we have a lot of successional vegetation in the Great Lakes region largely because of marginal lands that are no longer, at least under 2005 grain prices, were not considered profitable enough to clear and plant. Now that may well change. And we're seeing more marginal land coming under production this year I understand, just because of the double grain prices. And you might predict that. But there should be, and one of my hopes, is that we can inform policy to the point that eventually those systems that while they may be possible with higher grain prices, still be profitable for the standpoint of producing grain, they could be equally profitable from the standpoint of providing above-ground cellulosic material as feed stock. 

And it might be even more desirable and profitable if we figure out a way to provide incentives to farmers to pay for those services that those systems now not crediting for those services, the pollination services, the clean water services, the carbon sequestration services, and so on. A lot of those services will stay, regardless of whether those systems are cropped annually, that is, harvested annually, if they're done right. That means you've got to harvest them probably in the fall, and you've got to harvest them with enough cover left over for the wildlife, the birds in particular, over winter. But there are ways to do that in a sustainable way, I'm convinced. Now, I'm not sure that gets at your question with respect to that. 
- Do turning the poplars over time with harvesting and replanting, do the emission and sequestration approach those of a mature forest, or do they stay higher as the initial planting? 
- Yeah, that's a great question. Did everybody hear that? With respect to the poplars, do you expect a decline in their mitigation potential over time in the same way that you lose that mitigation potential with a natural forest, with an old growth forest. And the quick answer is, we don't know. 

I would expect the N20 levels to stay just as low as they are now. Simply because they're also low in the old growth forest. Whether we can build methane oxidation capacity in those systems is yet to be determined. That is, those systems have only been in place for 20 years. We haven't seen that capacity yet, but we know that a 50-year-old field has half of the capacity of an old growth forest. So maybe in another 30 years, that poplar stand will provide the additional oxidation, methane oxidation capacity that is not now showing. With respect to carbon sequestration in soil, we would expect it to plateau at some point. It's certainly not going to build up higher than the old growth forest, which in our case around 3% carbon. We've got around 1.4% carbon in the poplars now. Probably it will max out at 2.0% is my guess. 

Again, there are no ecosystem studies of biomass poplars that are longer than the ones that we've got here. So we're really at the edge of learning what those saturation periods are. 
(inaudible)
 
-...is not including, especially an old forest, the both above ground and below ground carbon pools. It seems like the most you talked about the grades, but the very large carbon pools, 
(inaudible)
 
- So the question was, why aren't we including the pools of carbon in the forest that are now in place as part of the accounting. 

And the answer is that we're interested in changes in pools to calculate the impact on CO2 emissions or CO2 sequestration. Now, it's not to diminish the value of those old forests for storing the carbon that they have. And this is the whole basis for deforestation being a flux. Were we to cut those forests, then they would turn into a flux and they would increase the atmospheric burden of CO2. But as they are, at equilibrium, there is no net change on a year-to-year basis in carbon storage. That's the definition of old growth. And so, there is no net, either positive or negative impact on mitigation or on the CO2 burden in the atmosphere. So we don't count it for that reason. 
- Would you speculate what you think the possible feedback from climate change might be on those balances across systems? Is it likely that it will just move things up and down or that they'll be differentially affected? 

- Yeah, that's another tough question. And that's what we're hoping the modeling will help inform. Climate change in the Great Lakes region is happening. We're seeing an increase frequency in droughts on the east side of the lake. We're also seeing changes in snowfall duration or snowpack duration. Of course, we're seeing the early onset of spring relative to recent history. And understanding the impacts of those changes on the future capacity of these biofuel landscapes to produce as much as they could produce in today's climate, it's an open question. And the different models are showing, as I'm sure you're aware, the different GCM models are showing different precipitation changes, depending on which model you're using. It's very difficult to predict the regional climate changes. We see warming, for sure, and that's going to have a big impact on lake level and groundwater flows, simply because there will be a lot more transpiration happening, so a lot more water vapor that would otherwise have ended up in the groundwater and in the lakes will actually end up back in the atmosphere. 

But beyond that prediction, I don't know if we can go very far. Certainly, however climate change effects cropping systems in general, they're going to have a similar effect on these cellulosic systems, with one exception. And that is mid-growing season droughts, as we've had at KBS for two of the last five years, will have a much lesser impact on a perennial system than they will on our corn and soybean systems. And so in that sense, that's a good point. In that sense, the biofuel systems, the cellulosic systems should be buffered from at least that kind of variability, the intra-annual variability in climate. 
- So maybe we should take one more and go out and have some coffee. Two more. 
- Two more, go ahead. Sorry. 
- I have read Tillman's much publicized study about prairie biomass, and also have seen your results, and wondered, those systems seem to offer global impacts and net benefits in terms of global warming impact, but they just aren't very productive. 

And I wondered if at Kellogg or elsewhere, other work you're familiar with, if people have tried fertilizing either the poplars or say the early successional old fields to see if you can still get most of those benefits, but also greatly increase production? 
- Yeah, great question. So the question was with native prairie systems, the data that's been published thus far, and the advocates for those systems are advocating systems that aren't as productive as the monoculture, or even biculture grass systems. And, it's true. On one of those initial slides, I had productivity values for grasslands. And those are grasslands that one might find in central Kansas or in the Great Lakes region, which are on the order of three to four metric tons per hector per year, which is about half of what you could get, probably. We don't know this for a fact, because we're doing the experiment now. But probably, if we were to get the same switch grass productivity that others have found in a recent PNS paper in farms across South Dakota, and Nebraska and so on, we would get about half the productivity in an unfertilized grassland. Now we do have fertilized old fields at KBS, and we can show that we can boost the productivity of those to around seven metric tons per hector. So we can get equivalent yields from the old fields as we can from the monoculture switch grass, which is really interesting. 

Now the down side of that, is that interest have been a lot of experiments all over the U.S., all over Europe, as well, in the past 15 years looking at the impact of fertilization on biodiversity. And in general, fertilizing reduces plant biodiversity in native prairie. And so the trade off there would be greater productivity, but less plant biodiversity. And that's why those who are proponents of native grasslands haven't gone the next step, in saying, well what happens if we fertilize those grasslands. Yes, you can boost productivity. We know that. But at what cost. If the aim is to increase biodiversity at the same time, you're increasing cellulosic feed stocks, then you have to ask how do you balance the biodiversity against the increased productivity. That's one of these trade offs that are going to be true in any kind of analysis and important to understand. One final question, I hear? 

- Sort of two parts. One is just with your KBS research, I'm just curious, how generalizable that is? You showed at the beginning all these marginal lands that could be utilized with different soil types in the eastern U.S., for example. Also, I'm just kind of wondering if in your analysis, you're going to be looking at, and making comparisons to sort of second growth forests as long-term sinks, sort of these general land uses versus the biomass production, because I'm kind of imagining from that first map you showed, abandoned lands that could be reincorporated, you know, south eastern Ohio. I'm from Ohio, so I'm picturing kind of poplar plantations harvested every 20 years there, versus the second growth forest that's probably there now. That's a really different landscape, and if those are getting converted, you might be gaining, you know, you can store extra carbon in the soil, but the above ground processes and the ecosystem has really changed. 
- You might have equivalent productivity for either of those two systems, poplar or secondary forests, depending on how their managed. I should say unfertilized poplar. Right now, our unfertilized poplar, and our poplar is unfertilized, because we put it in as a biofuels crop back in 1988, when the thought what is that we would only be growing biofuel crops on marginal land, and farmers would only be interested in them because they didn't require any inputs. That is to say that they didn't really have much value, economic value. 

So we decided at the outset to manage these as effectively unmanaged, but initially planted poplars. And the productivity in those stands is quite high. It's about 10 metric tons per hector per year. But a successional forest, once it gets to a certain point, you might expect a similar sort of productivity, some fraction of that. There again, you have to ask, you know, what trade offs are you willing to make. Do you really want monoculture poplar stands across south eastern Ohio versus successional forests that might be a little less productive, but might provide all of those other biodiversity services that a monoculture poplar can't. So I think those are exactly the kind of questions we need to consider, as we think about what are the optimal landscapes for biofuels. I mean there's no question-- I shouldn't say there's no question. There's little question that we're going to be moving into this economy, we've already started. And we now need to make choices. 

Well, we really don't want the equivalent of Iowa corn fields covering all of what is now in successional forests across the U.S., planted to a similar woody monoculture. So we need to be having the discussions and be thinking about how to quantify the biodiversity benefits in addition to the strict biofuel benefits. As far as KBS being generalizable, we're looking at ecological processes in these systems. And these processes occur everywhere. Because we're comparing systems we would expect the same sort of comparisons to hold, the same sort of differences to hold, no matter whether you're on a KBS alpha soil with a rainfall of about a meter per year, or you're in south eastern Iowa on less soil with a little bit less precipitation. The relative differences should be the same. So not exact, of course. 
- I want to thank Phil again, and invite everyone to come on outside to have some coffee and talk for a while. 
(applause)