By Lara Bryant & Daniel Rath
One often-repeated criticism of cover crops is that they don’t work in certain regions because it’s too cold or too dry to grow them. While it is true that different climates and geographies can present unique challenges to farming, cover crops are adaptable, valuable and effective enough that farmers can benefit from them in every region of the United States. We have spoken to farmers who grow cover crops successfully in every climate from Canada to Texas to California to Maine and want to share their secrets for success.
The potential benefits that cover crops provide are well-known. They can help suppress weed growth, add nitrogen, improve soil structure and water infiltration, control erosion, and improve soil biodiversity. While there are multiple other agricultural practices that can also deliver these benefits, such as compost addition, the wide variety of cover crop choices and associated practices makes them one of the more versatile tools in a farmer’s toolbox. Being clear about the goals that a farmer wants cover crops to help them achieve is the first step in determining whether cover crops are the right choice for a particular field.
Growing Cover Crops in Cold Climates (Up North)
Even in states where the growing season is a mere four-and-a-half months long, cover crops can help farmers meet specific on-farm goals that they cannot achieve just by having cash crops in their rotation. Thanks to farmer innovation and extension services producing state and region-specific guidelines, cover crops have been successfully integrated into farming systems in all the northernmost US states, from Maine to Montana and everywhere in between. According to the 2017 Census of Agriculture, the number of acres of cover crops planted in North Dakota doubled from over 200,000 to over 400,000 acres. Practices like overwintering a cereal rye cover crop can help control early season weed emergence in the spring, control excess moisture during the spring thaw, and reduce wind erosion during the winter.
We spoke with farmers in Minnesota, North Dakota, and South Dakota who have been growing cover crops for as long as 15 years. They saw tremendous benefits of cover crops, like reduced erosion, weed suppression, and cattle enjoying the forage. They emphasized that growing cover crops reduced risk by creating more stable conditions for planting and harvesting, improved yields, and reduced losses in a bad drought year. They said that sometimes planting cover crops is tricky, and even they sometimes had to back off from planting seeds in a very dry year. When asked about tips for growing up North, they said that getting in early behind harvest to plant cover crops is key. Craig Rau, who farms in north central South Dakota, says that “I try to get out early with the no-till drill to plant cover crop seeds, and get them in as soon as I harvest.”
Knowing the goal that we want cover crops to achieve will make difficult questions such as timing, cover crop choice, crop rotation, and termination style a lot easier to answer. Do you want to reduce erosion during the winter by ensuring the presence of living roots? Planting winter rye immediately after a fall harvest, then terminating early in the spring may be the best option. Do you want to plant some late-season grasses for grazing? Oat and barley are cool weather grasses and can last longer into the winter. Thanks to the hard work of farmers, researchers and extension agents, cover crops can be a viable choice for farmers in cooler climates no matter the length of the growing season.
Growing Cover Crops in Dry Climates (Out West)
Cover crops can also be a viable option in water-limited regions such as New Mexico, California, and Montana. In Texas, farmers planted over 1 million acres of cover crops in 2017, an increase of 11% from 2012. Some cover crops use only slightly more water than would be lost from a fallow field - the difference can be less than a single day’s worth of irrigation! The water those cover crops use is then put to good use. Even in arid regions where every drop of water is precious, cover crops can increase soil organic matter, reduce erosion and improve soil structure without negative effects on yields. Cover crops can also help increase water infiltration and storage during extreme weather events, to ensure that less water is lost to runoff.
North Valley Organics in New Mexico is a great example of how cover crops can be incorporated in the Southwest. The farm practices cover cropping by planting rows of perennial cover crops, like clover and native grasses, next to their vegetable crop beds, and then rotating the rows every few years. They maintain the perennial cover crop strips with mowing. The benefits to their farm show in their high organic matter (6%) and high-yielding vegetable crops. Farmers Minor Morgan and Matthew Draper don’t rely on cover crops alone; other practices, like drip irrigation and laser leveling, improve water use efficiency on their land. Morgan says that a paradigm shift needs to happen in how people look at farming; instead of focusing on yield, you need to give back to the soil. He sees that as an investment that has paid off on his farm.
There are numerous resources dedicated to helping farmers in arid regions (such as the American Southwest) find the strategies that work best for them. Farmers in water-limited areas often need to be much more proactive about cover crop termination to reduce water usage and prevent seeding. Farmers with saline soils may rely on more salt-tolerant cover crops such as barley that have a better chance of survival. Combining cover crops with other practices such as mulching and reduced tillage can help reduce water loss while increasing organic matter content and reducing weed pressure.
Cover crops are not a silver bullet for the issues that farmers face, but they are a valuable and versatile practice that can be adapted to fit almost any farm system and climate. Cover crops also work well with other regenerative practices, like adding compost, reducing tillage, and agroforestry that have huge benefits for producers. Innovative producers and agronomists in all 50 states are learning more every day about how to optimize cover crops to fit farmer’s needs. The NRDC supports policies that help farmers grow cover crops, like the COVER Act sponsored by Representative Casten (IL), because we know that farmers in almost every climate in the US can benefit from cover crops. While it’s true that there are challenges associated with cover crops, especially in dry or cold climates, these challenges are being overcome every day by farmers who see cover crops as a valuable tool in their toolbox.