Cover crops show power of diversity

In the five years brothers Keith and Brian Berns have been growing cover crops and selling cover crop seed for their business, Green Cover Seed, they’ve become one of the most widely known names in this latest trend in no-till.

Cover crops show power of diversity

In the five years brothers Keith and Brian Berns have been growing cover crops and selling cover crop seed for their business, Green Cover Seed, they’ve become one of the most widely known names in this latest trend in no-till.

Although his family has been no-tilling on their farm near Bladen in south-central Nebraska for 25 years, Keith says taking the step into cover cropping has been a learning experience.

“The first thing I’ve learned is I’m not smarter than God,” he says. “What we try to do with cover crops is look at how God created plant communities and ecosystems and try to learn from and mimic that in what we do in our farming operation.”

In nature, something is always growing above and below ground, and cover crops are considered one of the keys to mimicking this. However, nature is also diverse. Research at Brown University has shown different species cooperate in times of stress rather than competing.

Key Points

Diverse plant species cooperate in times of stress, rather than competing.

Best way to add diversity is to expand the crop rotation by double cropping.

Companion cropping allows a cash crop without it being a monoculture.

Power in diversity

Berns says it’s the same with cover crops — something he noticed while first growing cover crops through USDA’s Sustainable Agriculture Research and Education program in 2008. “It became obvious as we watched different species grow that they were doing better in diverse mixes compared to monoculture,” he says.

Species diversity means more living roots to host a healthy population of mycorrhizal fungi. So, fewer inputs are required as more species share nutrients and moisture across the mycorrhizal bridge when cash crops aren’t growing, and there’s less insect and weed pressure as different species break up the pest cycle.

“If you think about it, the most competitive plant any other plant can have is one of the same type. Your roots are going to be at the same depth, the canopy is at the same height, you want everything at the same time,” Berns says. “If your neighbor is a different type of plant, simply the fact you’ve got different root structures, different nutrient needs at different times means it’s a different environment than a monoculture.”

The best way to add diversity is to expand the crop rotation by double-cropping and harvesting a cereal crop in summer, which opens up the planting window and the amount of time cover crops can grow. “I’ve not only got a really long growing period where I can grow biomass and carbon, but all those roots are going to release all the different exudates into the soil,” Berns says. “I’m feeding my soil biology for an extended period.”

This year, Berns took it a step further, double-cropping 300 acres of sunflowers after triticale — along with eight companion crops growing beneath the canopy, including chickling vetch, lentils, crimson clover, mung beans, buckwheat, flax, Florida broadleaf mustard and yellow mustard. After experimenting with companion cropping corn on a small scale, Berns says sunflowers have been more conducive to companion cropping.

Double cropping usually means growers can’t qualify for crop insurance for the second crop, making it an ideal time to plant companion crops. Because companion cropping prevents growers from collecting crop insurance, it doesn’t always work for everyone, but it does diversify a crop rotation while harvesting a cash crop. “You can grow a cash crop without it being a monoculture,” Berns says. “And you’ve got all this diversity growing down below.”

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COVER CROPS COOPERATE: Brown University research shows diverse plant species cooperate rather than compete under stress, and Keith Berns says cover crops behave the same way, sharing nutrients and moisture across the mycorrhizal bridge.

This article published in the October, 2014 edition of KANSAS FARMER.

All rights reserved. Copyright Farm Progress Cos. 2014.

Cover Crops

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