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Last April I said: "I'd wager that we will see growers producing crops for cellulosic ethanol who use biochar amendments to reduce their costs and increase their profits." It looks like I'd have won that wager.
. . . they are looking at nutrient recycling in a holistic manner by replicating the nearly closed nutrient cycle of integrated crop and livestock systems. These integrated systems, once widespread, use manure as fertilizer and make use of legume plants such as alfalfa and clovers to replace nitrogen in the soil. To help close the nutrient cycle in the case of cellulosic biorefineries, the research team is experimenting with two types of alternative cropping systems, and examining how effectively switchgrass, used Nutrient Recovery from Integrated Cellulosic Biorefineries as a biofuel feedstock, utilizes nutrients recovered from biorefineries. In the process of converting switchgrass and other kinds of biomass into liquid fuels, the researchers hope that nitrogen (as gaseous ammonia) and other nutrients (as ash) can be recovered during the gasification process. The researchers will then assess the impact of applying the recovered materials back to the biomass production plots.I'd rather not see good forage used for biofuels. However, though they are doing the wrong thing they are doing it the right way. Now if we could get them to do the right thing the right way . . . Or, perhaps we should just count our blessings.In addition to protecting the quality of the soil, there are other benefits to nutrient recycling, according to Anex. Cycling captured ammonia back to production fields can reduce the need for synthetic nitrogen fertilizer inputs, which would bring down the amount of fossil fuel energy needed to grow biomass feedstocks. Also, when the nitrogen is combined with a substance called agri-char or bio-char that is produced by biorefineries, it creates an attractive soil additive that can significantly increase crop yields, while removing carbon from the atmosphere. Brown estimates that a 250-hectare farm on a char-and-ammonium-nitrate system could sequester 1,900 metric tons of carbon a year.
“We are trying an integrated approach to maximize the efficiency and, therefore, the viability of cellulosic biorefineries: we are trying to evaluate the agronomic value, the [carbon] sequestration value, the economic value, and the engineering,” said Brown.
"1,900 metric tons of carbon a year" X 3.7 = 7,030 tons CO2
Total CO2 Equivalence:
Even before the total CO2 equivalent credits are validated they should be on the product label. Once a commercial bagged biochar soil amendment product, every suburban household can do it,
The label can tell them of their contribution, a 40# bag = 150# CO2 = 160 bags / year to cover my personal CO2 emissions.( 20,000 #/yr , 1/2 average)
http://www.epa.gov/climatechange/emissions/ind_calculator.html
But that is just the Carbon!
I have yet to find a total CO2 equivalent number taking consideration against some average field N2O & CH4 emissions.
Soil structure seems the basis of N2O emissions;
http://a-c-s.confex.com/crops/2008am/webprogram/Paper41955.html
On nutrient leaching;
http://a-c-s.confex.com/crops/2008am/webprogram/Paper41910.html
Farmers can now get C credit for No-till at the CCX Carbon Exchange, Biochar puts No-till soil carbon gains to shame.
Erich
"Soil structure seems the basis of N2O emissions;
http://a-c-s.confex.com/crops/2008am/webprogram/Paper41955.html"
N2O is produced by denitrifying bacteria. They use nitrates and produce N2O. Actually, there are several bacterial strains that either consume or produce a number of nitrogen compounds until finally it is N2, which is the last step. I doubt that soil bulk density is the effect of biochar that reduces nitrogen loss, it is the ability of biochar to lock up nitrates so that bacteria can't eat it, and then release the nitrates when enzymes produced by plant roots free it. Or so I have read.
"On nutrient leaching;
http://a-c-s.confex.com/crops/2008am/webprogram/Paper41910.html"
This paper speculates that "the observed interaction between biochar treatments and manure additions is that readily mineralizable N-containing organic compounds from the manure were adsorbed and stabilized by the biochar". This is the sort of effect noted above that prevents bacteria from consuming nitrates and so producing N2O. I think that they may be mistaken that it is organic nitrogen that is adsorbed though. I think that it is nitrates - produced by bacteria that have mineralized the organic nitrogen compounds - that are adsorbed by biochar.
That first paper also notes that CO2 emissions increase. That may have something to do with soil bulk density since the CO2 is produced by aerobic bacteria - oxygen breathers - and improved soil aeration favors them over anaerobic bacteria which would otherwise do the decomposition of organics and produce CH4. Said another way, CO2 increased but CH4 decreased, and so would not, as they claim, "partially offset the C sequestered by addition of the biochar". And, since CH4 is a more potent GHG, they could do some equivalence calcs that would further enhance the net benefit of using biochar. But, the experimental design was flawed and they didn't measure CH4.
It is also worth noting that the aerobic bacteria that decompose cellulose, producing CO2 as waste, also consume nitrates. There is competition for nitrates between plants and bacteria. That's why the addition of manures can throw swards into nitrogen deficits, stunting plants at first. Once the organics are mineralized by bacteria then nitrate levels rise again over time. Adding biochar into the mix in effect adds a competitor since it adsorbs nitrates, but also favors plants which can cause biochar to release locked nitrates.
There's just a lot of stuff going on in the soil. I'd like to see more and better designed experiments before we start making personal offset arguments that turn out to be stuff and nonsense, or so contingent on particular applications that nothing can be truthfully said without full information. The reason to use biochar is that it improves soil and makes better use of nutrients. You can sell that without a bunch of emissions cruft.
Posted by: back40 at September 23, 2008 10:05 PM