Vulnerability, exposure and sensitivity may not be terms you expected to use when you got into farming. Yet, according to author-scientist-farmer Laura Lengnick, these terms are key to the new language of growing produce in our changing climate. There are multiple options available to determine your land’s vulnerabilities, exposures and sensitivities. Perhaps the easiest place to start is with soil testing. The U.S. Department of Agriculture’s Natural Resources Conservation Service (USDA-NRCS) offers free soil testing and works with farmers to develop land management plans unique to their location and cropping system. Soil Solutions and Cover Crops
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Standard practices that benefit soil health in any location are cover cropping, encouraging friendly bacteria and fungi, eliminating nitrogen fertilizers and synthetic inputs, and direct seeding.
“A cover crop is your ‘aspirin a day,’” said Christine Clarke, Massachusetts state conservationist, USDA-NRCS. “Make sure your soil is covered, and you’re protecting it like your brand-new toy in your garage. It’s a precious resource, and a fundamental resource. If you protect your soil, you’re going to inherently protect your water. It’s the ultimate filter.”
At Many Hands Organic Farm in Barre, Massachusetts, Julie Rawson planted clover and daikon radish under and between each row of vegetable crop. “You have to get used to a mess,” Rawson said. Cover crops create soft edges where there used to be precise rows. Beneath the “mess,” a web of activity is happening that boosts soil health and mitigates climate change.
The daikon radishes’ deep root system encourages earthworm activity and more microbial activity than shallow root crops. It increases the amount of water infiltration in the soil profile. In general, deeper root crops create a better soil health profile than shallow root crops, like grasses and forbs. As water travels deeper into the soil, it reduces compaction issues. “If you have a clay pan a foot or so down because you’ve plowed the land for years and years, these roots are strong enough to penetrate the clay pan, break that up and provide a deeper soil profile,” said Curtis Elke, Idaho state conservationist, USDA-NRCS.
Cover crops with deep roots help mitigate climate change by pulling more carbon from the air and then releasing more liquid carbon into the soil than shallow roots. That liquid carbon feeds the microbes that create soil aggregates. Aggregates produce more porous soil, which holds water better in droughts and in floods. In some areas heavy rain can delay planting and create problems obtaining a good stand of plants, which can reduce crop productivity. As reported in the Third National Climate Assessment, in soils with even modest slopes, rainfall of more than 1.25 inches in a single day leads to runoff that causes soil erosion and loss of nutrients and can lead to flooding.
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“If we want to survive we really have no alternative but to restore carbon to the soil,” Jack Kittredge reported in “Soil Carbon Restoration: Can Biology Do The Job?” “That this can be done through biology, using a method that has worked for millions of years, is exciting… Farmers can follow these simple principles and not only restore carbon to the soil but help rebuild the marvelous system that nature has put in place to renew our atmosphere while providing food, beauty and health for all creation.”
Integrating cover crops into your system
According to Idaho’s state conservationist, there’s not one cover crop mixture that works for everybody or works throughout the year. Still, Elke encourages many farmers to rotate cash crops on a four-year cycle. Alternating potatoes with wheat, sugar beets and then another grain is a four-year rotation mixing high-residue with low-residue crops. Although wheat provides the soil significant straw residue, he said the common practice of rotating only potatoes and wheat is not enough. “That’s why we’re encouraging cover crops in low-residue crop years,” he said. “Right after the potato or beet harvest, you go in and plant that cover crop to add that extra residue and organic matter into that soil profile.”
Florida’s state conservationist Russell Morgan said traditional winter cover crops, such as cereal rye, crimson clover, vetch and brassicas, work well with northern Florida’s row crop production systems. For the southern Florida vegetable production areas, he suggested summer growing cover crops, including “exotic” legumes such as hairy indigo, sunn hemp, cowpeas or velvet beans, in combination with sorghum-sudangrass or pearl millet.
According to Morgan, Florida’s diverse agriculture presents many challenges to soil health. Crops include vegetables like potatoes; myriad specialty crops such as citrus, blueberries and sugar cane; and row crops such as corn, cotton, soybeans and peanuts. In addition, high year-round temperatures and rainfall make it harder to increase the organic matter content in Florida soils. “Luckily, Florida has more options for utilizing more and different cover crops than many areas of the country because we have both winter and summer production systems,” Morgan said.
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In Massachusetts, conservationists reported shifts in pest activity – including different timing and locations – resulting from climate change. The solution to such shifts is not newer, stronger pesticides, but rather soil health. “The soil biota is no different than the biota in your gut,” Clarke said. “Everything has to be balanced to work correctly.” Just as friendly bacteria in the human digestive tract encourages physical health in part by discouraging unfriendly bacteria, a healthy soil biota encourages plant health in part by discouraging pests and encouraging beneficial insects.
“Farmers cannot do much to change their exposures, but they can do a lot to change their sensitivity and their adaptive capacity,” said Lengnick, author of “Resilient Agriculture.” In conjunction with soil testing, the framework in Lengnick’s book, “Resilient Agriculture,” may be a useful tool to show you the areas of vulnerability in your growing operation over which you have control.
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