What does Soil Carbon Research Program (SCaRP) tell us?
This could be baffling. After 3 years and $25m the message coming out of the Soil CarbonResearch Program seems to be: land management decisions have little impact on the amount of carbon sequestered in the soil. Rainfall zone and soil type have a big impact on soil C levels, but not the farmer. I don't get it. We lost 50% of our soil carbon in the last 100 years. What caused that if it wasn’t the impact of soil
management practices?
After analyzing 20,500 samples from 4500 locations, the largest soil
sampling exercise in Australia’s history, the researchers concluded that no practice
was any better than any other at improving carbon levels in soil. No grazing method or tillage practice or any other management approach stood
out. (See Table 1.)
SCaRP vs Chan:
CSIRO’s
Dr Jeff Baldock, who managed SCaRP, says the soil sampling was not conducted
to quantify sequestration of carbon in soils. “The three year duration of the
study would not allow estimates of carbon sequestration to be derived with high
certainty. The samples therefore are a baseline measurement of the soil carbon
stocks within the various combinations of soil type by management regime within
each agricultural region,” he says.
While
the impact of climate, soil type and management regime was studied, there was
an ingredient missing: the farmer. The skill level of the farmer
in the agricultural practice that they nominate will affect the result. That
skill level could be directly related to the length of time the practitioner
has been practicing. Every successful practitioner will tell you that it can
take several years to get their system right. It is not a matter of simply
applying a ‘practice’ to an area of land to get a standard response.[1]
Overlooked in the first
analysis were a group of “high performance” soil carbon managers who have
demonstrated a potential well beyond the average. “These ‘outliers’ present a
challenge for the conventional estimation of the potential of Australian soils
to sequester carbon. If these outliers can do it, it can be done.
Dr Baldock acknowledged this in his report: “Differences in the way individual
landowners implement practices in response to personal preferences or business
requirements may also contribute significantly.” He points to a case study where
the water use efficiency of continuous cropping systems ranges from 60% to 90%
across a region due to landowner abilities and preferences. “Under these
conditions, differences in the input of carbon to a soil will result and soil
carbon values will vary even under similar soil, climate and topographic
conditions.”
In his
presentation of the results of the SCaRP, Jeff Baldock pre-empted the shift in
the paradigm: that it is not the management practice we must study to
understand the potential for soil carbon, but the particular farmers in whose
hands the practice can produce the results that led Professor Ross Garnaut to estimate that soil carbon could account
for 40% of Australia’s emissions. "We need to catch and analyse samples that do not fit current
calibrations," says Dr Baldock. The absence of a pattern is "at least
partially due to variability that existed within management classes." Here
he identifies the existence of high performance carbon farmers. Farmers don't
perform uniformly within a management class - many are
average, and some are very good. When you average them the results tell you
nothing about the potential of the class. There is no allowance for skills,
time spent learning the technique, incentive of carbon offsets, etc. As the old song goes...
"It ain't what you do, it's the way that you do it.
"It ain't what you do, it's the way that you do it.
"It ain't what you do, it's the way that you do it.
"That's what gets results."
[1] Another issue that could
influence the outcome would be the combination of practices, which is common.
Eg. grazing management and pasture cropping and/or compost tea inoculant
applied to the same paddock.
