The greening of November

By TRACY FRISCH
Contributing writer

LIVINGSTON, N.Y.

 

David Goldstein, coordinator of the new research project Hudson Carbon, walks through a field with a blend of at least nine different cover crops at Stone House Farm in Livingston, N.Y. The research effort will track the farm’s carbon cycle -- and the role cover crops play in mitigating climate change. Scott Langley photo

In the dairy country of eastern New York, fall is traditionally the time when cornfields are shaved down to stubble – to remain brown and lifeless until next year’s planting.

But on a growing number of fields around the region, farmers are choosing instead to keep their soil clothed in plants throughout the winter, rather than leaving it exposed to the destructive forces of harsh weather. From small-scale organic growers to large-scale dairy operators, farmers are discovering and spreading the word about the benefits of cover crops, which include winter rye, hairy vetch, oats, field peas and a range of other plants.

Cover crops, also known as “green manures,” are grown to improve the health of the soil, rather than as crops to sell or use for animal feed. Instead, these plants are turned back into the soil or cut and used as mulch. Planting cover crops takes time and money, but supporters say the investment is more than recouped in benefits to the soil’s productive capacity, which in turn reduces the need for synthetic fertilizers.

The practice is hardly new. Keeping the soil covered with green plants year-round is one of the hallmarks of sound land stewardship, a habit agricultural and conservation agencies have been preaching since the Dust Bowl of the 1930s.

Healthy, productive soil is still the main goal for most area farmers growing cover crops. But lately some see another important benefit to the wider world: Cover crops soak up carbon from the air and integrate it into the soil, thereby curbing the effects of climate change.

At Stone House Farm in Livingston, Ben Banks Dobson has become one of the most avid and large-scale cover croppers in the Hudson Valley since he took over as the farm’s manager more than four years ago. Now Stone House has launched a new research project aimed at demonstrating how farmers can use cover crops to sequester atmospheric carbon while increasing the carbon (and therefore, the organic matter) in the soil.

Elsewhere around the region, farmers report that, in addition to the main goal of improving soil health, cover crops help to mitigate the effects of extreme weather events – from heavy rains to drought – that have been attributed to climate change in recent years.

 

Key to going organic
At Stone House Farm, Dobson says the mission is to “bring regenerative agriculture back to our landscape.”

The farm, on 2,000 acres in Livingston, a rural town in southern Columbia County, has been converting to organic production over the past three years and will qualify for organic certification this month. Some 1,200 acres are planted in crops like corn, soybeans, wheat, field peas, oats, barley, buckwheat, rye, vetch and spelt. There are also hayfields and pasture that’s rotationally grazed by beef cattle, and the farm operates its own feed mill.

Cover crops have been central to Dobson’s vision for the farm.
“I grow cover crops to give back to the soil,” Dobson said. “We’ve really started seeing benefits.”
Dobson has accelerated the timeline for boosting soil health and organic matter by using complex cover crop mixtures of many different species. These mixtures contain various grains and legumes along with things like buckwheat and tillage radish to produce large amount of biomass. Everything except the rye and vetch is killed by winter’s hard freeze, making the cover crop easier to manage come spring.

On lighter soils, Dobson said Stone House Farm no longer need to plow in its cover crops before planting corn and soybeans in the spring. Instead, the farm uses a 31-foot-wide device known as a roller crimper to knock down the cover crop and crush its stems, leaving a mat that acts as a barrier to weeds and also protects the soil.

In the first two years of the farm’s transition to organic, yields of soybeans, corn and wheat were down relative to those from conventional, agrochemical-dependent agriculture. But now, in the third year, soybean yields are up to 48 bushels an acre, wheat has almost doubled to 65 bushels, all of it food grade, and the farm is expecting a very good corn crop, comparable to what would be achieved through conventional farming, Dobson said.

Meanwhile, input and seed costs are a little lower than they were when the farm used chemical inputs. Before Dobson took over, the farm was spending $80,000 a year for herbicides, other pesticides and chemical fertilizers. Under organic management, he said, the farm spends $25,000 more on labor and diesel fuel. But the market value of certified organic crops such as corn, soy and wheat is two to three times the value of their chemically grown counterparts.
During the transition to organic, Dobson said the farm developed a considerable market for feed crops that aren’t genetically modified. Besides producing pre-mixed rations for various types of livestock, Stone House Farm also sells wheat for milling and barley for distilling. Its cover-crop seed supplies Roxbury Farm, a large community-supported organic farm in Kinderhook, among many others.

Dobson, 32, grew up on his parents’ vegetable farm in the Berkshires and has run or worked on a series of farms since dropping out of high school at 16. For a couple of seasons he managed his father’s farm, which specializes in salad greens. He also worked at farms in the Dominican Republic, Hawaii and Haiti. In coastal Maine, he started and eventually sold a 200-acre farm that produced organic salad greens.

“I spent years taking jobs and figuring out how to do them,” Dobson said, adding that he learned through “trial and error and a lot of reading.”

At Stone House Farm, he reports to an oversight committee. The Rockefeller family owns the farm. (Abby Rockefeller and two of her siblings recently took over from their father, David.) Despite the wealth of its owners, Dobson said financial viability is a key consideration in all of the farm’s activities.

“Although we have more resources than most farms, we operate under a tight budget,” he said.

 

Tracking the path of carbon
When Dobson realized what was happening in the soil as Stone House Farm transitioned to organic production, he started hatching the plan for what would become a decade-long research project called Hudson Carbon.

The project, a partnership with Rodale Institute, has the objective of “mapping the carbon cycle on our farm,” Dobson explained. Stone House Farm was able to launch the project with in-house funding but will be starting soon to raise donations to sustain it, he said.

The Hudson Carbon project, which began last year, involves conducting a wide variety of tests, five times a year, at a dozen test sites on pasture and croplands across the farm. Among the tests are measurements of soil carbon at several different depths in the 3-foot-deep cores at each site.

The farm is working with Woods End Lab in Maine on soil health testing, and Woods Hole Marine Biology Lab in Massachusetts is helping to monitor the farm’s soil for carbon dioxide emissions. An isotope test allows the researchers to determine whether nitrogen and carbon in the soil are coming from cover crops, inputs like compost or other sources.

In the spring, the farm will produce its first report with data from the test sites. The report also will document the farm’s agricultural practices and all of its inputs, outputs, and expenses and income.

“Ultimately we intend to start a voluntary regional carbon market,” Dobson said. “We want to come up with a mechanism where farmers farming this way could sell carbon credits.”

 

From the air to the soil
David Wolfe, a Cornell University horticulture professor whose research into the impacts of climate change on agriculture dates back to the early 1990s, said cover crops can make an important contribution to reducing carbon dioxide emissions.

Much of the public-policy discussion on how to limit the effects of climate change has been focused on figuring out “how we can scrub the air of carbon dioxide,” Wolfe noted.
“Plants have been doing that for a long time,” he said. “They are zero-risk geo-engineering.”
Through photosynthesis, plants take up carbon dioxide and convert the carbon in that greenhouse gas into sugar, which serves as a building block for other compounds they produce.
So by keeping vegetation in the ground throughout the year, farmers who grow cover crops boost the amount of carbon dioxide captured by living plants on their farms. When cover crops die and decompose, some of the carbon stays in the soil, rather than dissipating into the atmosphere.
Although researchers observed several decades ago that plants have so-called “leaky roots,” it took more sophisticated instrumentation to discover that bacteria and other microbes are taking up the sugars and other compounds exuded by plant roots. This exchange occurs as part of a symbiotic relationship in which microbes in the soil deliver nutrients to plants in exchange for energy-providing sugar from the plants. Sometimes plants excrete as much as one-third of the sugars that they make through photosynthesis into the soil.

“That’s something that I didn’t learn about in grad school,” Wolfe said.
Plants probably have evolved to do this to attract beneficial bacteria, he explained.
Symbiotic bacteria also team up with legumes to “fix” nitrogen. That means plants in the legume family – including such traditional cover crops as clovers, peas, beans and vetch -- leave behind carbon and also contribute nitrogen, which plants require, to the soil.

“It’s almost like free nitrogen,” Wolfe said.

Using legumes to enrich soil with nitrogen, he explained, allows farmers to reduce or eliminate their need for synthetic nitrogen fertilizers – bypassing an industry that has a large carbon footprint.

Protection against floods, drought
As one of Columbia County’s leading organic growers, Chris Cashen considers cover crops to be an essential strategy for good farming. At The Farm at Miller’s Crossing in Claverack, he and his crew grow about 75 acres of vegetables, selling mainly to wholesale customers including the supermarket-size Honest Weight Food Co-op in Albany. The farm also rotationally grazes a herd of beef cattle.

“I use cover crops to provide as much organic matter as I can,” Cashen said. “Organic matter is the key to aerating the soil. It also allows water to penetrate, rather than run off, when it rains hard. Without organic matter, soils can become like clay. It’s all about soil structure.”

Besides using cover crops to create healthier soil, Cashen relies on them to help keep weeds at bay. And cover crops serve as a tool for transitioning rented land to organic production. (The Farm at Miller’s Crossing is certified organic by Stellar, a biodynamic label.)

With a $500 combine from the 1940s, Cashen harvests cover-crop seed. He uses much of it on the farm and also sells surplus seed in 1-ton totes to other organic farmers from as far away as Washington County, 80 miles to the north.

One reason Cashen said he feels so strongly about using cover crops is the disruptive impacts of climate change. His commitment has grown stronger “after living through Irene, Sandy, Bertha and all the other bad storms that came through,” he said.

The Farm at Miller’s Crossing consists of bottomlands that flood and dry uplands, now served by extensive irrigation infrastructure. In the old days when the farm was a dairy, the lowlands were the corn ground, and the higher ground was in orchard. The farm now grows vegetables on both types of ground, ever vigilant to the potential for weather-related damage.

“I try to plan for worst-case scenarios of flood and drought,” Cashen said. “We’re not the first generation to experience floods and drought, but maybe this will be our reality.”

Echoing Cashen’s concern about extreme weather fueled by climate change, Wolfe, the Cornell professor, said another benefit of cover crops – helping to hold the soil in place – is particularly relevant.

In the Northeast, one of the most significant effects of climate change has been the increased frequency of heavy rainfall. In this region, a heavy-rainfall event is defined as at least 2 inches of rain within a 48-hour period. These storms can result in increased soil erosion.

Since the 1950s and ‘60s, the Northeast has experienced a 70 percent increase in the number of days with heavy rainfall compared with historical averages, Wolfe noted. That’s a greater increase than anywhere else in the nation.

 

Complex planning required
Cashen strives not to grow vegetables on any given field for more than two years in a row. After that, he’ll rotate that field out of vegetables into cover crops for at least 6 months and ideally for a full year.

“You have to be disciplined to parcel out some good ground for cover crops,” he said. “With organic, there’s no shortcut. You have to set yourself up for success.”

Besides growing cover crops for their many soil-related benefits, Cashen said he takes advantage of their bonuses, which for his farm are “straw, seed and feed.”

In the spring, Cashen said he mows some of the winter rye for straw to use as mulch on the farm. But converting too much of the yield from cover crops to other uses risks undermining the purpose of growing them, he warned.

“If you forget you’re growing winter rye for its organic matter, it becomes tempting to start selling straw,” Cashen said. “Sometimes economics can get in the way of good husbandry. I don’t think anyone ever sets out to be a poor farmer, but when you’re trying to maximize all your investments, ... it happens.”

Cashen, one of nine children, is the first in his family to make his livelihood through farming since his grandparents bought the Claverack property in the 1950s. Before they moved back to the Cashen farm, his wife, Katie Smith, farmed at Klinekill Organic Gardens on rented land in Chatham. The couple has four children.

For Cashen, as a vegetable grower juggling 30 different crops, some that require successive plantings throughout the season, cover cropping requires good planning. In deciding which cover crops to plant where, he selects from a panoply of choices.

“It’s like a spreadsheet,” he said.
Each crop comes with its own preferred conditions and particular benefits. It’s up to the farmer to weigh them all and decide which to grow where and when.

 

Alternative to manure
Roxbury Farm, which celebrated its 25th year this summer, also is devoted to growing cover crops in the context of its mission of producing organic vegetables. The operation is one of the largest community-supported farms in the region, with nearly 1,100 shareholders. Jody Bolluyt manages the farm with her sister Carrie.

In 2000, Roxbury relocated to a former potato farm in Kinderhook. Its soil had a very low organic matter content and a huge accumulation of weed seed, Bolluyt said.

Because turning around poor soil conditions is a long-term project, Roxbury Farm dedicates almost as much land to cover crops as to vegetables, which are now grown on 30 acres. The farm also raises sheep, cattle and pigs, and lesser-quality land, such as fields that flood seasonally or have wet spots, is set aside for pasture and hay.

Roxbury Farm also inherited other problems from the potato farm.
“Phosphorus levels are off the charts,” Bolluyt noted.

Phosphorus is an essential plant macronutrient, but when present in excess it tends to bind with other important elements like calcium, making them unavailable to crops.

Composted manure is high in phosphorus, so Roxbury Farm, to avoid exacerbating its existing mineral imbalance, doesn’t use compost as a soil amendment. Instead, the farm makes aggressive use of cover crops for building organic matter.

Other objectives reinforce the importance of cover crops.
“We don’t like to leave the soil bare,” Bolluyt said. “Erosion would occur, and also weeds would come in.”

On a quick tour of the vegetable land, Bolluyt listed the latest sequence of cover crops on each of the fields. The farm’s 13 vegetable fields all have names, rather than numbers, and the successive plantings of these crops are complex.

A field might be planted in winter rye in August, then sorghum the next June, followed by berseem clover and oats in late summer in preparation for tomatoes and squash the next year. Or Roxbury will put in oat and peas for the fall, buckwheat the next spring and then a vegetable crop for fall, leaving enough time to get in winter rye.

One cover-crop mix of crotalaria and sorghum grew 10 feet tall, Bolluyt said. Next they planted oats and peas. Finally, the next spring, the ground would be ready for two years of vegetables.
One neat trick the farm tried was sowing crimson clover under fall cabbage in July at the time of a final mechanical cultivation. In early October, after the cabbage had been harvested, a beautiful, deep mat of clover blanketed the ground.

 

Economic boost for a dairy farm
As a partner at Landview Farm, a 1,350-cow dairy farm in the Washington County town of White Creek, Mark Anderson grows cover crops within a set of constraints and according to a logic that are rather different than those of organic vegetable farms like Roxbury and The Farm at Miller’s Crossing.

For one, the economic realities imposed by commodity-scale agriculture are much harsher. And as Landview grows only two crops, feed corn and alfalfa (because they produce the most feed value) plus a fall cover crop, the farm has far fewer options for building biological complexity and the resilience it brings.

Anderson, 57, got his first farm job at age 11 and rented a farm and milked cows while attending SUNY Morrisville. He said today’s impossibly low milk prices and horrible margins leave him chasing anything that could improve his farm’s efficiencies. A new mower that covers a 30-foot-wide swath, for example, can do the work that four men used to do, and a new guidance system on the farm’s fertilizer spreader cut fertilizer costs by 15 percent. Landview even goes to the trouble of delivering its milk to a plant in Connecticut to get a better price.

But even as Anderson grapples with how to minimize costs and optimize outputs on all fronts, cover crops are one thing that he is unwilling to give up. That’s because he has experienced the healing effects that cover crops exert on the land.

Ironically, Landview made its first foray into cover cropping mainly to maximize its corn acreage. Anderson explained that he and his partners agreed to plant a fall cover crop in 2000 for the express purpose of gaining permission to grow three consecutive years of corn. Without a cover crop, the Farm Service Agency, an arm of the federal government that loans money to farmers, would not have allowed Landview to plant corn in the same field more than two years in a row. (Instead, they’d have had to seed the fields into a hay crop like alfalfa or grasses and clover.)
Today, Anderson considers himself a strong proponent of enhancing soil health. Along with growing cover crops, he cites eliminating tillage, using manure, and crop rotation as key practices.

“It’s like a big wheel, and each spoke supports the wheel,” Anderson said.
Planting a fall cover crop has become an integral part of Landview Farm’s operations. On a Friday in mid-October, the farm crew was completing the fall cover crop planting.
“This year, as we took off a field of corn, we had a no-till drill behind the harvester, so we’re caught up,” Anderson said.

That’s quite an accomplishment, as many of the 2,400 acres that Landview uses for crops were planted in corn.

In the spring, cover crops help to dry out the farm’s soil, which tends to be on the wet side. Cover crops also moderate soil temperatures and protect the soil surface from harsh sunlight.

“Now we’re starting to see biological benefits,” Anderson said. “The part that we’re just learning about is how cover crops held build soil biology. We’re seeing more earthworms. They say the soil should look like black cottage cheese, and it’s looking more and more like that.”

In healthy soil, biological glues bind together the individual particles of soil into aggregates that harbor beneficial microorganisms and hold oxygen and moisture, which plants need. These soil aggregates are one of the things that make living soil so different from inert sand. Sand alone has no water-holding capacity, Anderson explained.

 

Experimenting and learning
Like most farms that haven’t embraced organic practices, Landview Farm relies on herbicides to kill or euphemistically “terminate” its cover crops.

When Anderson and his partners started growing winter rye as a cover crop, they were extremely cautious. In early spring, they would use herbicides to kill the winter rye when it was only 6 to 8 inches tall. At that size, the rye hadn’t produced much biomass, and this greatly limited its benefit to the soil.

But after gaining more confidence, the partners would let the rye grow to 18 to 20 inches in height before killing it. Anderson said it reaches that size sometime between early March and late April, depending upon the year.

This year, Anderson had to confront his worst fear when his cover crop got away from him. Faced with 6-foot-tall rye, he used a farm implement called a roller to knock it down and sprayed several herbicides in order to plant corn into it.

“It was scary, but it worked out well,” Anderson said. “In the future, we will either terminate the cover crop earlier or let it grow to 4 to 5 feet in height.”

For the past several years, Anderson said he has been looking to Lucas Criswell, a farmer active in the Pennsylvania No Till Alliance, for guidance as he deepens his commitment to cover cropping. Criswell, who is transitioning to crops that aren’t genetically modified, reports he is using fewer and fewer soil insecticides, Anderson said.

Anderson said Landview’s corn “doesn’t look as good as everyone else’s until later in the season,” potentially making it a poor advertisement for cover cropping. But while corn planted into winter rye may take a little longer to take off, Landview’s corn also tends to stay green longer than other farmers’ corn, he said. He wonders whether the soil’s increased moisture-holding capacity or the role of cover crops in recycling of nutrients could be responsible.

“For every percentage point of organic matter you add, an acre-inch of soil will hold 20,000 gallons more water,” Anderson said. “That means when the rain hits the fields, the soil will hold onto it instead of it running off.”

Anderson described how cover crops help to recycle nutrients through the soil.
“When we plant rye in the fall, there are nutrients in the soil left over from the corn crop,” he said. The winter rye grabs free nutrients left over from fertilizer and manure applications and ties them up in its plant tissue. When the rye plants die and decompose, soil bacteria release these nutrients, making them available to the next corn crop.

 

Curbing runoff and water pollution
In Vermont, cover crops have gained a much stronger hold overall. One-third of the state’s 90,000 acres of corn are cover cropped, primarily with rye, said Heather Darby, a University of Vermont agronomist.

“We doubled our cover-cropped acreage in a year,” Darby said. “You see everything’s green out there. I have not seen the same in New York,” which she characterized as “far behind.”
“It’s really exciting what’s happening out there,” she said. “While you’d like to think it was all driven by extension,” Darby, who’s been “preaching this for a long time,” recognizes that the trend is driven by something bigger.

“All these pieces are coming together,” Darby said. “You’re seeing it in the popular farm press, in magazines from ‘American Agriculturist’ to ‘The Furrow’ from John Deere. Farmers are talking about organic matter. It blows my mind.”

Of course, many farmers have not yet adopted the practice of cover cropping. Darby said many of them “believe it works and that there are benefits, but they’re still figuring out how to make it work on their farm.”

The momentum for cover cropping has been growing among Vermont farmers over the last five years, Darby said.

In Vermont, the connection between agricultural practices and water pollution has been clearly articulated, and farmers are being collectively held responsible for the damage caused.
“There’s been a lot of public pressure for farmers to use cover crops because of the high phosphorus levels in Lake Champlain,” she noted.

To encourage farmers to grow cover crops, the Natural Resource Conservation Service, a federal agency, provides good cost sharing, she said.

Another factor is the urgency of adapting to climate change. Farmers had “several years of poor crops due to heavy rains, and now some people have drought,” Darby said. With farmers already adopting cover crops to reduce runoff and water pollution, she believes they’re also realizing it makes sense to manage their soil for the erratic weather too.

“The writing is on the wall,” she said.