Page 11 - Ebook_CoverCrops2022_Final

When .you .start .thinking .about .your .farm .as .an .ecosystem, .instead .
of .a .chemistry .set, .then .that’s .when .we .can .really .start .doing .
ecological .benefits .for .the .environment .

—MacCauley Kincaid .
Missouri .producer

reduce greenhouse gas emissions. That’s why them to conclude in the paper that “inclusion of
cover crops are a key part of the Biden admin- CCs (cover crops) into agricultural rotations can
istration’s strategy to use agriculture to help cut potentially increase soil carbon sequestration.”
U.S. emissions in half by 2030.
“The results clearly show that if we manage our
To keep the carbon from returning to the air, croplands properly, then we can increase the
the biomass has to stay in the ground, which is carbon stock,” Jian said.
why effective carbon sequestration also requires
management practices that don’t break up the Additionally, the study found that soils planted
soil, said Rattan Lal, a renowned soil scientist with cover crop mixes had larger soil organic
at The Ohio State University who was awarded matter increases than mono-species cover crops.
the World Food Prize for his research around Legumes and legume mixtures also saw signif-
restoring soil fertility and carbon sequestration. icant soil organic carbon increases, while grass
and grass-legume mixtures did not change soil
When plants photosynthesize and take in carbon organic matter significantly.
dioxide, they create biomass, one of the most
common forms of soil organic carbon below Jian said legumes tend to do better than grasses
and above the ground. That biomass returns to with storing soil organic carbon because they
the same land where the plants are growing and, tend to have more biomass and a low car-
over time, gets broken down by soil microbes bon-to-nitrogen ratio.
into humus — a substance similar to compost,
but made without oxygen. “Combined, these two tend to have a good feed-
back to the soil organic carbon,” Jian said.
“Grow a cover crop,” Lal said. “Suppress it,
mow it, but don’t plow it. Then, carbon will stay Soil types also play a role. Fine-textured soils
in the soil.” saw a 39.5% mean change in soil organic car-
bon after cover crops, while coarse-textured and
Jinshi Jian, a former research associate at the medium-textured soils saw mean changes of
Pacific Northwest National Laboratory-Univer- 11.4% and 10.3%, respectively.
sity of Maryland Joint Global Change Research
Institute, was part of a group of scientists that
collected 1,195 soil organic carbon compari- Too .dry? .Too .cold? .Cover .crops .won’t .
sons from 131 different studies and conducted a work .for .me, .some .farmers .say
meta-analysis that looked at soil organic carbon
changes after the use of cover crops. Farmers cite several challenges with cover
crops. One is the additional time and labor they
The researchers found that cover cropping require; some 38 of 66 cover crop non-users
caused a 15.5% increase in soil organic carbon surveyed by SARE and the Soil Health Institute
in soils at or above 30 centimeters deep, leading raised that concern.

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