May/June 2019Welcoming the WormBy Chanda Cooper
Ongoing research and innovative practices are restoring life to agricultural soils.
One Saturday morning last October, I saw a land planarian oozing its way alongside a corn field on my family’s farm near Bishopville. It was the first time I’d spotted such a creature on our land, and its appearance was equal parts fascinating and horrifying. Its body was long - maybe seven inches - and light brown. Its skin was nearly translucent, stretched thin like a strand of linguini with two black racing stripes along its back. Its shovel-shaped head nosed along the ground, leading the rest of its stringlike body in a fluid forward motion. In its wake, a slime-trail gleamed in the sunlight.
The land planarian is a flatworm, in the same phylum (Platyhelminthes) as parasitic tapeworms and liver flukes. But the land planarian is no parasite; it is a voracious predator, and the soft bodies of earthworms are its chief prey. Native to Indo-China from Vietnam to Kampuchea, land planarians were documented in American greenhouses in 1901, a mere twenty-three years after they were first discovered in a greenhouse at Kew Botanical Gardens and given a Latin name (Bipalium kewense). Dispersed in the soil of potted plants through the horticultural trade, they are considered a common greenhouse resident throughout the southeastern U.S., along the Atlantic Coast and in California. Of course, once here, the flatworms didn’t restrict themselves to the greenhouse environment. In temperate and subtropical areas where they can survive the winter temperatures, they have moved out into the natural environment and begun feeding on native earthworms.
Until recently, I imagine our farm fields offered little succor for such a creature. The sandy agricultural soils of eastern Kershaw County were low in organic matter - the decomposed remains of plants, animals and other organisms that contribute to soil health - and our fields were subjected to a variety of agricultural disturbances. As a result, earthworms were absent, and an earthworm-eater like the land planarian would have been hard-pressed to eke out a living. This is, I presume, why I had never seen one here before. I interpret its new presence on our farm as confirmation that things are changing: our soils are being restored, and the earthworms are returning!
We planted our first cover crop on this farm in the fall of 2014, after I’d been following the research of University of South Carolina Associate Professor Dr. Buz Kloot and his team of farmer-scientists for twelve months. As a research volunteer representing the Richland Soil and Water Conservation District (SWCD), I had helped them pull seasonal soil samples from fifty-nine acres of cropland spread across one hundred miles of sandy South Carolina coastal plain as a part of a USDA-NRCS-funded research project, and I was convinced by their results. I had seen earthworms shoveled up in a conventional soybean field; soil pH values holding steady in cover-cropped fields without the addition of lime; concentrations of soil nutrients like phosphorous and potassium holding steady, and sometimes even increasing, without the addition of fertilizers. Farmers were saving money as their soils regained health and organic matter, as soil ecosystems were rebuilt and soil biology was restored. The following spring, the soil organic matter on my family’s farm was 1.5 percent in the cover-cropped field - twice as much as the 0.7 percent in an adjacent field that had been left fallow. One year after that, we saw mushrooms growing between soybean rows for the first time, ever.
When I first met Buz Kloot, he was working on another USDA-NRCS grant to produce a video series called Under Cover Farmers. The videos highlighted farmers in North Carolina who began planting multispecies cover crops and documented the benefits those cover crops conferred, from increased water infiltration and moisture holding capacity in their fields to reduced erosion, better weed control, increased fertility, and more resilient cash crops. Kloot and I sat opposite each other at a conference table and worked our way through a grant proposal to bring the work into South Carolina, first by partnering with pioneering farmers to introduce multispecies cover crops to the state, then by sharing those farmers’ stories. The grant was funded, and we have been fast friends and inter-agency collaborators ever since.
“There was a lot of skepticism and even cynicism” about soil health in the beginning, Kloot says. But things changed. Five farmers and three SWCDs joined his research, and at the end of that first collaboration, the South Carolina Soil Health Movement was officially underway.
There's a photo on Kloot’s professional Facebook profile of Dillon County farmer Doug Newton peering into a microscope. Newton recently became interested in emerging techniques to rebuild soil microbiomes, including via the Johnson-Su composting process. This technique, developed by Dr. David Johnson and his wife and collaborator Hui-Chun Su, creates an incredibly rich, microbially-active compost which can be used to inoculate agricultural fields with life. Best of all, the Johnson-Su method is practically free, and it encourages the growth of native, locally-adapted soil microbes rather than relying on imported or commercial strains of organisms.
Last year, Newton established a Johnson-Su compost bioreactor on his farm, and he and Kloot recently put the composted product under a microscope to see what life it harbors. Their first find was a bacterial-feeding nematode - one of the “good guys” in a healthy soil community.
Nematodes are non-segmented roundworms, typically microscopic, and are one of the most abundant and widespread animals on Earth. They can be found in almost all habitats and occupy a variety of ecological niches. While a few nematode species are root feeders and are therefore considered agricultural pests, most soil nematodes feed on bacteria, fungi, protozoans or other nematodes and are therefore benign or beneficial. They can help make nutrients available to plants, stimulate plant growth through grazing, maintain microbial communities through predation, and even suppress plant diseases.
Kloot, Newton and other farmers pursuing soil health are keen to re-establish and maintain the populations of bacteria, fungi and micro-invertebrates - including protozoans and nematodes - in their fields. They are hopeful that the Johnson-Su composting process can produce a microbe-rich soil amendment that can be used to inoculate a field with a “starter community” of soil microbes. Once established, farmers can cultivate the microbial community by feeding it with cover crops and protecting it from tillage, fertilizer salts, pesticides and other disturbances.
With a microscope and a little training, a farmer can identify the protozoans, nematodes, fungi and other denizens of the soil community and thereby obtain a measure of the vitality of a fields’ soils. But one soil resident testifies to the healthiness of a soil community, even without a microscope: the earthworm.
Because of their large size, earthworms are a conspicuous indicator species for soil health. And until recently, most southeastern agricultural fields were earthworm deserts. With minimal organic matter in the winter-fallow sandy soils and frequent mechanical disturbance by plows, disks and subsoilers, earthworms had no food source and faced hostile conditions at best. But in recent years, farmers who have begun reducing or eliminating tillage and planting diverse cover crops have seen in-field earthworm populations explode.
Last spring, ten-year-old Addie Lewis, whose uncle was one of the five farmer-participants in Kloot’s initial South Carolina project team, completed a fourth-grade science fair project titled “Cover Crops and Soil Health.” In one of several investigations, Addie established three square-foot plots in a field with cover crops and three square-foot plots in a field without cover crops. “I used a tape measurer to measure out the plots,” she explains in her lab report. “I marked each corner with a flag. I used a spade to remove and inspect the soil in each marked area down to a depth of six inches and counted the number of earthworms in each sample.” Addie found no earthworms in the fallow field, but the plots in the cover-cropped field held four or five earthworms each.
Some thirty-four species of earthworms have been documented in South Carolina, and I’m not yet sure which species are living on my family’s farm east of Camden. I do know, though, that our fields are becoming more hospitable places for these earthworms and their associates to survive. My dad is in the field (it’s November as I write this) planting the cover crop blend we ordered a few weeks ago: twenty pounds of rye, six pounds of vetch, four pounds of crimson clover and two pounds of daikon radish. This cover crop will provide a food source and create a hospitable environment for the nematodes, bacteria, fungi and other beneficial microbes which will, in turn, nourish the earthworms and the crops themselves.
In the spring, Dad will terminate the cover crop and plant corn and soybeans using a no-till drill so as to disturb these soil communities as little as possible. Kloot and his team of farmer-scientists will continue experimenting with the Johnson-Su compost inoculant, determining the most effective and efficient ways to create and apply inoculant at the farm-scale. As for me - inhabiting the space between farming, research and outreach - I will continue to follow the work of scientists like Buz Kloot and agricultural pioneers like Doug Newton; to share their results with people like my dad who will, in turn, apply these discoveries to the land; and to celebrate the return of creatures like the earthworm, the nematode, the fungi and the bacteria. Strange and elusive as these creatures may be, they signify something powerful: change, restoration and hope.
Conservation Poster Contest
Each year, the National Association of Conservation Districts, the S.C. Association of Conservation Districts and local conservation districts partner to host a conservation poster contest for students in grades K-12. The 2019 Conservation Poster Contest topic is “Life in the Soil: Dig Deeper,” and it encourages students to learn more about the complex soil ecosystems that maintain the soil’s health and productivity.
Soil is the foundation for many of the items we use in our daily life, such as food, clothing, clean water, homes and more. One characteristic of healthy soil is the presence of a diverse community of living things, including earthworms, insects and other arthropods, protozoans, fungi and bacteria. How humans treat the soil affects how many and what types of organisms can live there. Students are invited to learn more about soil life and about the conservation practices that promote soil health. Then, they can create a poster to show others what they’ve learned about life in the soil!
Each S.C. Conservation District sets its own county deadline and sponsors awards at the local level. Posters must be submitted for judging at the local level before they can progress to the statewide competition. Contact your local conservation district office for more details! To find your local conservation district office, visit http://www.dnr.sc.gov/conservation/. Monetary prizes at the state level are sponsored by the S.C. Association of Conservation Districts; prizes at the national level are sponsored by the National Association of Conservation Districts Auxiliary and the Albert I. Pierce Foundation.