Thank you for taking the time to knock down the claims of the grazing crowd. It is about time that TED Talk pulls that infamous video with a public apology, or submit to a rigorous, side-by-side evaluation of the claims in comparison with a no-grazing and reverting to grassland / forest option.
Fantastic analysis and video! There is another set of claims concerning regenerative animal-based agriculture that is also questionable. These claims concern composted cattle manure and soil carbon sequestration, in relation to a set of studies conducted by Silver, Ryals, and De Longe . These studies presented data indicating that applications of compost to ag land could generate net soil carbon sequestration in the range of 150-990 lbs/yr/acre. These studies used plant-based compost to generate such results. Can cattle-based composted manure simply be substituted to generate the same results? I am going to post below my analysis of this question from a few years ago so that it can accompany Mike's brilliant analysis and video. Anyone who is willing to seriously engage with regenerative animal-based ag advocates needs to be prepared to handle both aspects of the regenerative animal-based ag ideology. It takes a lot of cow manure (78,000 lbs) to produce a lot of composted manure (62,400 lbs) to apply to an acre of land to get a net soil sequestration of atmospheric carbon (mostly via sequestration of atmospheric CO2 ) in the range of 150-990 lbs/yr/acre (converting from the original 51-333g/m2/acre of C figure presented in the studies). I am assuming that since carbon is 27.291 percent of CO2 by mass, the amount of net atmospheric CO2 that is sequestered on this acre of land is likely in the range of 553-3627 lbs/year. It takes 3.616 years for a beef cow to produce that 78,000 lbs of manure. Over that time, the beef cow will emit 477.3 pounds of methane (at 60 KG/yr). At GWP 34 (100 year interval), that is 16,228 CO2 equivalents, at GWP 86 (20 year interval), that is 41,047 equivalents. It takes a lactating dairy cow 2.6712 years to produce that much manure. Over that time, a lactating dairy cow will emit 641.1 pounds of methane (at 109 KG/yr). At GWP 34, that is 21,796 CO2 equivalents, at GWP 86, that is 55,133 CO2 equivalents. It is going to take a number of years before the soil organic carbon sequestration levels created by the compost treatment exceed/counterbalance the CO2 equivalency emissions associated with the enteric fermentation methane emissions coming from the cows, depending on the GWP used. We also really do not know what the soil carbon sequestration levels will be over time, though DeLonge argues elsewhere that it might continue for 20 years. If one uses the GWP of 34 and the maximum number in the soil sequestration range, the equalization/counterbalanced point occurs in 4.47-6.00 years (beef cow-lactating cow). If one uses the maximum range number and the GWP of 86, the equalization point occurs in 11.32-15.20 years (beef cow-lactating cow). If one uses a mean or median number relative to the overall range presented by Silver, Ryals, and De Longe, the counterbalancing time will substantially increase, regardless of whatever methane GWP is used. (I personally think that using a mean or median value is much more reasonable than using the high -end-of-the-range value.) As one can see, whether this approach works with regard to composted cattle-based manure depends on the assumptions and numbers that are used. If the compost is plant-based, then there are no problems. With regard to soil carbon sequestration, I conclude that plant-based compost is good! As for cow-based compost -- maybe (if one uses soil carbon sequestration values at the high end of the Silver/Ryals/De Longe study range spectrum and methane GWPs associated with long-time intervals), or maybe not (if one uses mean/median soil carbon sequestration values and methane GWPs associated with short-time intervals) This animal-based manure composting approach would work best for chicken, turkey, and pig-based manure (as there are no or insignificant methane emissions due to enteric fermentation). I do believe that wherever there are large concentrations of manure, the manure should be composted and applied to the land. Now whether we want to encourage the creation of such large concentrations of manure, well . . . that is another question altogether. I do not believe we should encourage this. Ranchers receiving carbon credit-related payments for creating such concentrations of manure would encourage this. Ranchers should also have to pay a carbon tax concerning the net atmospheric methane emissions their cows produce. The CO2 equivalents of those methane emissions should be calculated using the most recent IPCC methane GWP associated with the 20 year interval. Sincerely, Todd Shuman at tshublu@yahoo.com (email me should you want more info concerning this analysis)
For a potent critique of the related and broadly-distributed Alan Savory claims concerning rotational livestock grazing and soil carbon sequestration, see journals.uair.arizona.edu/index.php/rangelands/article/view/19616/19249 Another good more general critique of Savory-style livestock grazing can be viewed here ... www.hindawi.com/journals/ijbd/2014/163431/abs/
Very deep analysis debunking grazing as a better alternative to non grazing. And of course as expected forests are the best!
This study enables the results to speak for themselves. Thank you Mike.
Thank you for taking the time to knock down the claims of the grazing crowd. It is about time that TED Talk pulls that infamous video with a public apology, or submit to a rigorous, side-by-side evaluation of the claims in comparison with a no-grazing and reverting to grassland / forest option.
Fantastic analysis and video! There is another set of claims concerning regenerative animal-based agriculture that is also questionable. These claims concern composted cattle manure and soil carbon sequestration, in relation to a set of studies conducted by Silver, Ryals, and De Longe . These studies presented data indicating that applications of compost to ag land could generate net soil carbon sequestration in the range of 150-990 lbs/yr/acre. These studies used plant-based compost to generate such results. Can cattle-based composted manure simply be substituted to generate the same results? I am going to post below my analysis of this question from a few years ago so that it can accompany Mike's brilliant analysis and video. Anyone who is willing to seriously engage with regenerative animal-based ag advocates needs to be prepared to handle both aspects of the regenerative animal-based ag ideology.
It takes a lot of cow manure (78,000 lbs) to produce a lot of composted manure (62,400 lbs) to apply to an acre of land to get a net soil sequestration of atmospheric carbon (mostly via sequestration of atmospheric CO2 ) in the range of 150-990 lbs/yr/acre (converting from the original 51-333g/m2/acre of C figure presented in the studies). I am assuming that since carbon is 27.291 percent of CO2 by mass, the amount of net atmospheric CO2 that is sequestered on this acre of land is likely in the range of 553-3627 lbs/year.
It takes 3.616 years for a beef cow to produce that 78,000 lbs of manure. Over that time, the beef cow will emit 477.3 pounds of methane (at 60 KG/yr). At GWP 34 (100 year interval), that is 16,228 CO2 equivalents, at GWP 86 (20 year interval), that is 41,047 equivalents. It takes a lactating dairy cow 2.6712 years to produce that much manure. Over that time, a lactating dairy cow will emit 641.1 pounds of methane (at 109 KG/yr). At GWP 34, that is 21,796 CO2 equivalents, at GWP 86, that is 55,133 CO2 equivalents.
It is going to take a number of years before the soil organic carbon sequestration levels created by the compost treatment exceed/counterbalance the CO2 equivalency emissions associated with the enteric fermentation methane emissions coming from the cows, depending on the GWP used. We also really do not know what the soil carbon sequestration levels will be over time, though DeLonge argues elsewhere that it might continue for 20 years. If one uses the GWP of 34 and the maximum number in the soil sequestration range, the equalization/counterbalanced point occurs in 4.47-6.00 years (beef cow-lactating cow). If one uses the maximum range number and the GWP of 86, the equalization point occurs in 11.32-15.20 years (beef cow-lactating cow). If one uses a mean or median number relative to the overall range presented by Silver, Ryals, and De Longe, the counterbalancing time will substantially increase, regardless of whatever methane GWP is used. (I personally think that using a mean or median value is much more reasonable than using the high -end-of-the-range value.)
As one can see, whether this approach works with regard to composted cattle-based manure depends on the assumptions and numbers that are used. If the compost is plant-based, then there are no problems. With regard to soil carbon sequestration, I conclude that plant-based compost is good! As for cow-based compost -- maybe (if one uses soil carbon sequestration values at the high end of the Silver/Ryals/De Longe study range spectrum and methane GWPs associated with long-time intervals), or maybe not (if one uses mean/median soil carbon sequestration values and methane GWPs associated with short-time intervals) This animal-based manure composting approach would work best for chicken, turkey, and pig-based manure (as there are no or insignificant methane emissions due to enteric fermentation).
I do believe that wherever there are large concentrations of manure, the manure should be composted and applied to the land. Now whether we want to encourage the creation of such large concentrations of manure, well . . . that is another question altogether. I do not believe we should encourage this. Ranchers receiving carbon credit-related payments for creating such concentrations of manure would encourage this. Ranchers should also have to pay a carbon tax concerning the net atmospheric methane emissions their cows produce. The CO2 equivalents of those methane emissions should be calculated using the most recent IPCC methane GWP associated with the 20 year interval.
Sincerely, Todd Shuman at tshublu@yahoo.com (email me should you want more info concerning this analysis)
For a potent critique of the related and broadly-distributed Alan Savory claims concerning rotational livestock grazing and soil carbon sequestration, see journals.uair.arizona.edu/index.php/rangelands/article/view/19616/19249
Another good more general critique of Savory-style livestock grazing can be viewed here ... www.hindawi.com/journals/ijbd/2014/163431/abs/