By Amy Mayer
Jordan Clasen of Grade A Gardens in central Iowa didn't set out to be a chicken farmer. But his egg-laying hens save him about $2,000 a year on organic fertilizer.
Organic farmers can’t use chemical fertilizers, leaving them limited options for adding nutrients to their soil. One way is by using animal waste but researchers are still trying to pin down the science of grazing livestock on organic fields.
Consumers are buying more certified organic fruits and vegetables every year, and in the Midwest and Plains states, much of it is grown on small farms.
To comply with organic rules, some use livestock to provide natural fertilizer. Two separate studies in Iowa are trying to quantify the soil health, yield and, eventually, economic impact of grazing animals on the fields after vegetables are harvested.
In eastern Iowa, Mark Quee manages the farm at the Scattergood Friends School and Farm, growing fruits and vegetables for the boarding-school students and staff. He also has a handful of cows and calves, some turkeys, pigs and a few sheep.
Portable electric fencing lets Mark Quee control which vegetable plots he allows sheep to graze on at the Scattergood Friends School and Farm in West Branch, Iowa.
Portable electric fencing lets Mark Quee control which vegetable plots he allows sheep to graze on at the Scattergood Friends School and Farm in West Branch, Iowa.
“We’re strongly committed to having livestock on our gardens as much as possible,” Quee said.
That’s because they nurture the soil with their rooting, pecking, stomping and, yes, pooping. Quee’s seen firsthand how turkey manure increases soil nitrogen — a fact supported by commercial sales of composted turkey manure as an organic-approved fertilizer.
But he’s been curious to know whether letting the sheep graze after he harvests a cash crop such as broccoli will improve next year’s crop. So with another farmer, and help from agricultural nonprofit Practical Farmers of Iowa, he set up a formal trial.
The plots are quite small, and he sets up portable electric fencing to control where the sheep are allowed to graze.
“It’s kind of a pain to plant,” he said, “but if it gives us good data it will be worth it.”
Last year, the trial only looked at broccoli, with the farmers measuring size and weight at harvest. The results, Quee said, were inconclusive.
“It’s hard a lot of times in these smaller trials to get meaningful results,” he said. “So this year, we added a lot of soil testing.”
Ajay Nair has the same questions about the tangible benefits of grazing.
The Iowa State University horticulture professor and extension fruit and vegetable specialist hears from many organic farmers who want to try grazing because they think it will be beneficial but also want details on what to expect — both on the field and in their ledgers.
“Nobody could quantify, OK, if I have chickens what value does it bring in terms of adding organic matter to the soil? How does the nitrate content change?” Nair said.
Using a small federal grant, Nair and a graduate student designed a study to see how a flock of broiler chickens would impact the soil. Last year, the chickens pecked and nibbled on a field that had grown broccoli from inside lightweight, portable coops that were moved around the test plot on a daily basis.
This year, the researchers planted lettuce in areas that never had chickens and the ones that did.
The demand for organic food has increased every year. In the Midwest and Plains states, organic produce is often grown on smaller farms.
“We do see benefit in terms of having the same quality of lettuce but with reduced input,” Nair said of the plots that had chickens. “We did not apply any nitrogen. It was already there.”
That’s good for several reasons: The soil is healthier, there’s less added nitrogen that could be lost to waterways and farmers could potentially save money on fertilizer.
Nair cautioned his study is limited and he doesn’t have concrete numbers that could influence the cost-effectiveness of adding chickens to a farm. But he said he’s encouraged by the soil quality results, and hopes to address additional questions in a larger, longer project.
At Grade A Gardens in the Des Moines suburb of Johnston, Jordan Clasen has all the evidence he needs. He has 300 egg-laying hens that he rotates through his fields, and their manure has drastically reduced his fertilizer budget.
“I was spending about two grand ($2,000) in fertilizer every season,” he said, “and now I’m letting the chickens kinda do that.”
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