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Concentration of CO2 in the Atmosphere

Got It Covered?

Cover crops are a popular option to protect the soil over the growing season. (www.mncorn.org)

Jessie Haas

What if you could protect your farm crops or vegetable garden from drought, flooding, weeds, and insect pests, all in one fell swoop? What if that method could also build soil, sequester carbon, and feed beneficial insects and pollinators?

No, it’s not fairy-dust. You don’t have to squeeze your eyes shut and believe. Instead open them, follow the research, and start planting cover crops.

This is more important than ever for large-scale farmers, as many weeds have developed resistance to herbicides. Crops are getting overrun with these unwanted plants, and the ever-increasing cycle of spraying is just not working anymore. Science predicted this, just as it predicted the wild weather we are getting with global warming, but ‘I told you so’ isn’t going to pay the mortgage or feed the world.

One solution is cover crops. These are plants like buckwheat, clover, rye, and many others, planted thickly to suppress weeds. Corn and soybean farmers who add cereal rye into their rotation have been able to eliminate the problem they were having with certain resistant weeds. Seems like a win, but farmers worry about finding a market for their rye. One solution is to graze it down, thus converting it to beef or lamb. But most corn and soybean farmers no longer raise livestock, and cover crops that “only” break the weed cycle seem wasteful, making it a hard sell.

But there are many other reasons to use cover crops. Keeping the soil continually covered with living plants is a key element to increasing soil carbon and fertility. It builds the spongy quality of soil that allows it to absorb excess water during heavy rains and to retain that moisture for crops during times of drought. Recent research at Cornell University has shown that a rolled cereal rye cover crop can increase water infiltration 63% over conventional tillage-based production. Farmers plant rye in the fall, then terminate it in late spring and plant soybeans, all in one pass, saving 34% on labor and 26% on fuel, a major win for the environment.

Other benefits: Soil containing a lense of water creates what’s called “sensible cooling.” That means, you can feel it. Cover cropping in the Midwest has been shown to decrease local summer temperature measurably; that’s good when the planet is heating up.

Some cover crops, like mustard and brassicas, produce chemicals that kill nematodes. Most, if allowed to flower, feed bees and butterflies; if planted early, buckwheat and cowpea cover crops also provide food for predator insects and cover for beetles that will later feed on destructive pests. Cover crops also feed the soil organisms that create healthy plants and sequester carbon.

Vineyards in California are experimenting with planting cover crops between the vines. Sheep are then grazed between the rows, eating the cover crop and weeds. They are trained to ignore grape leaves, but when grazing in hopyards, they are actually encouraged to eat the lower leaves of the hops, which creates better air flow and prevents diseases. Sheep are a better choice than cattle for this work, as they are smaller, easier to transport, and cause less soil compaction.

Cover crops in orchards can also reduce pest damage. A mix of rye and crimson clover grown between transplanted trees reduced flatheaded appletree borer damage by up to 95% in one recent study, as effective as using insecticides. The Rodale Institute has demonstrated that rolled cover crops are effective at weed suppression compared to black plastic, and greatly reduce plastic waste on the farm. Finally, legume cover crops provide soil nitrogen, and grass cover crops can take up excess nitrogen. This allows a farmer to grow healthy crops without paying for chemical fertilizer, which is a big greenhouse gas emitter and a big expense.

All this benefit just from growing more plants? If it seems improbable, remember that plants, over millions of years, created the atmosphere that makes our civilization possible. The more we find ways to partner with them, the more likely we are to keep it.

Jessie Haas has lived in an off-grid cabin in Westminster West, VT for 36 years. She is the author of 40 books for children and adults, most recently The Hungry Place.

Sources:

A_Whole-Farm_Approach_to_Managing_Pests (1).pdf

Cover Cropping for Pollinators and Beneficial Insects – SARE

Managing Cover Crops Profitably, 3rd Edition – SARE

Cover Crops for Sustainable Crop Rotations – SARE

New no-till guide for organic soybean production | CALS (cornell.edu)

 

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