It’s harvest time across the Midwest, and for many farmers that means soon they’ll take one last pass with the tractor to till the soil before winter sets in. But several Midwest scientists arenow saying this practice of intensive tilling is ruining the soil andcontributing to greenhouse gas emissions. And they say it’s time for achange in how farms are run. Farmers, however, say changing the way they operate simply to reduce the production of greenhouse gases could be expensive. The Great Lakes Radio Consortium’s Tim Post reports:
Transcript
It’s harvest time across the Great Lakes region, and for
many farmers that means soon they’ll take one last pass with the tractor to till the soil
before winter sets in. But several Midwest scientists are now saying this practice of
intensive tilling is ruining the soil and contributing to greenhouse gas emissions.
And they say it’s time for a change in how farms are run. Farmers, however,
say changing the way they operate simply to reduce the production of greenhouse gases
could be expensive. The Great Lakes Radio Consortium’s Tim Post reports.
(sound of wind through the soybeans, crickets)
(sound of tractor comes
up toward the end of graph)
On a windswept prairie, just northeast of the small Western Minnesota town
of Morris, in a field of corn and soybeans, a small group of soil
scientists are doing what many farmers do, they’re tilling the soil.
(sound of blades turning over soil)
It’s a typical farm scene, until the scientists roll up with what looks like
a big inverted fish tank on a front end loader. They are using this device
to determine how much Carbon Dioxide, OR CO2, comes out of
the soil when its tilled. C02 is a greenhouse gas.
Research technician, Chris Wente sits in the cab of the front
end loader, which holds the tank over the soil being tilled. The
tank collects what’s released into the air after the blade has turned
the soil over, and Wente measures the result.
“Now you can see look at the water vapor going up cause we are
turning over a moist soil, see the CO2 is already off scale, for the user
interface, you can watch and see how its flying, its really increasing
dramatically fast. ”
What they’ve found in 5 years of research is that when soil is broken,
there is a big “burp” of carbon dioxide. It happens for a couple of
reasons. First, there is some CO2 trapped in the soil that escapes when
the ground is broken. But turning up the soil also mixes oxygen with carbon
contained in the soil, and microbes then turn that carbon and
oxygen into carbon dioxide.
The experiment is the work of Don Reicosky, a USDA soil
scientist in Morris. Reicosky says intensive tilling is like setting a
match to carbon in the soil.
“Well when the black smith wants a hotter fire, what does he
do? He pumps air through it, and you see the coals glow as he does that,
because he is putting in more oxygen, and that oxygen results in a very
rapid oxidation and a very rapid burning and that what happens when you
till the soil, that’s a pretty good analogy.”
Reicosky says this “burning” has, over the last 150 years or so, used up 30
to 50 percent of the carbon in the soil, sending IT into the atmosphere as
Carbon Dioxide.
So Reicosky is using his findings to try to convince farmers to switch to
less intensive types of tilling, like low till or no till, where little or
no soil is disturbed.
Agriculture officials in Washington DC are in favor of that
approach. Bill Hohenstein, the director of the USDA’s Global
Change program office, says conservation measures are beneficial to the
environment and to farmers, even if it is a big change for some in how they
operate.
“But in the long run by improving the health of the soil
and enhancing the organic content of the soil you can improve water
retention, you can improve overall productivity and actually reduce things
like soil erosion and nutrient run off into water ways.”
The USDA is watching how the agriculture industry affects the amount of
green house gasses in the atmosphere. The Global Change program monitors
not only CO2 from the soil but also fossil fuels burned on farms, methane
produced by farm animals and their waste, and nitrous oxide that comes from
the use of fertilizer. Figures are preliminary, but scientists say farms
contribute
7 to 20 percent of the gasses that contribute to global warming.
(Sound of farmer walking through corn comes up under last graph and goes
into next)
But on a farm east of Paynesville Minnesota, the concern right now isn’t
about green house gasses, it’s how the corn looks ahead of this fall’s
harvest.
“It has to be just as good as last year, which will give us
right around 140 bushels of corn, that’s in the bin, which is not bad”
Dave Brinkman manages this 1000-acre corn and soybean farm. Brinkman uses
conservation tilling measures, plus he’s put in place several measures to
manage animal waste, and reduce the impact of chemicals on his
land. Brinkman is a conservation farmer, the kind that people concerned
about the environment like to see. But he says it’s not an easy thing to
get into for a lot of farmers, in part because it’s expensive.
“It’s a cost of machinery, to do different practices, and you
aren’t gonna just go and trade your whole line of machinery off, it costs
money, and that’s the thing to look at.”
Brinkman says his yields are the same or better than farmers who use more
traditional farming methods. But it took a few years to get to that
point. And Brinkman says right now low farm prices make it difficult for
farmers to make a living. When helping the environment hits the bottom
line, the environment sometimes can’t compete. For the Great Lakes Radio Consortium, I’m Tim Post.