HOLISTIC COWBOYS AND CARBON FARMERS - MEAT: A Benign Extravagance - page 239

in 1977, which reported that 'when shoots are grazed, root mortality frequently increases
and root extension and branches decreases. This root mortality could result in significant
increases in Soil Organic Carbon (SOC) over a relatively short time.' 40 Here, at last, was
peer-reviewed scientific confirmation of the fact that grazing triggers root death. However,
later I came across a 2009 research paper by Klumpp et al , entitled 'Grazing Triggers
Soil Carbon Losses by Altering Plant Roots.' 41 Klumpp and her colleagues had conducted
laboratory tests on 'monoliths' or samples extracted from temperate permanent pastures,
which showed that when grazing was increased from a very low frequency to five times a
year, there was indeed increased root mortality, but that this led to decreased root biomass
and lower levels of soil carbon. This happens all the time in the murky world of soil carbon
science - no sooner do you read a paper claiming one thing, than you find another showing
that in slightly differing circumstances the very opposite occurs. However there is one mat-
ter on which almost everybody is in agreement - that roots are more important than shoots.
The above ground biomass (leaves, stalks and so on) even when ploughed into the ground
and decomposed by microbes, make considerably less contribution to the carbon content
of the soil than the roots. According to one study, this is because it is more stable and lasts
over twice as long in the soil. 42
The much bigger question mark raised by Priority One is the scale of the rise in organic
matter that Yeomans anticipates, which is of a level of magnitude higher than those repor-
ted by mainstream scientists. In 2000, the IPCC listed carbon sequestration figures from a
large number of studies covering a wide number of methods applied to grazing and cro-
plands. The majority of reports listed improvements in the range of 0.1 to 0.5 tonnes per
hectare per year, while the mean for minimum tillage systems was 0.3 tonnes. 43 At this rate
(and providing the carbon level doesn't reach saturation point) it would take between 65
and 328 years to reach Yeoman's target of 32.8 tonnes. The only improvements noted by
the IPCC which anywhere matched the rate anticipated by Yeomans were when legumes
or other new species were introduced into native grasslands - resulting in annual increases
of between 0.36 and 3.34 tonnes. One survey of the planting of deep rooting grasses and
legumes in Colombian savannah reported an increase of up to 14.4 tonnes, far higher than
anywhere else. 44 However, the report of this study in Nature prompted a response from sci-
entists from Woods Hole Research Centre, who voiced concerns about the length of time
that this sequestration could be maintained, and the decline in biodiversity that would res-
ult from improving pastures in this manner. 45
Admittedly none of these studies examine land managed under a combina-tion of two or
all of the three conditions that Yeomans stipulates. None of the IPCC studies were listed
as being organic (though perhaps some of them were). The highly productive Rodale ex-
periment (see Box ) over a period of 21 years raised the proportion of carbon in the soil by
about 0.6 per cent in the organic livestock system, and 0.5 per cent in the stockless organic