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Ron (left) and David Rosmann
use long rotations and minimum tillage to grow healthy crops,
resulting in minimal pest problems. Photo courtesy of The Rodale
Institute 2005 from www.
newfarm.org |
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Farm Feature: Diversity In Every Field
And Pen
 Diversifies
crops within space and time
Plants
windbreaks and grassy field borders
Integrates
crop and livestock operations
Builds
soils with diverse organic mattern uses resistant crops
It's been two decades since Ron and Maria Rosmann began transitioning
their west central Iowa farm to organic. Their crops — soybeans,
corn, alfalfa, turnips, grasses, oats, rye and other small grains
— were certified organic in 1994. Their 90 stock cows and
650 broiler chickens followed in 1997, while their 20 antibiotic-free
Berkshire sows are “natural pork.”
Except for seed staining in their soybeans — transmitted
by bean leaf beetles — and aphids and leafhoppers in their
alfalfa, Rosmann Family Farms are bothered by few pests. While most
of their neighbors have readily switched to “biotech”
varieties, the Rosmanns’ corn and soybean yields, over a 20-year
average, are at least as high as the county’s.
“Things are working well here and there’s got to be
a reason — and it’s not just one,” says Rosmann.
“We look at it as a whole system.”
Biodiversity is hard at work above and below ground
On their fourth-generation farm near Harlan, the Rosmanns plant
windbreaks, grassy field borders and — for pheasants and quail
— native prairie species. Generous populations of lacewings
and ladybugs indicate that the Rosmanns’ commitment to biodiversity
is keeping predators in balance with prey. Nesting boxes support
three pairs of American kestrels, which return the favor by snatching
up small rodents.
Rather than alternating corn and soybeans every other year, the
Rosmanns’ primary rotation spans six years: corn, soybeans,
corn, small grains and two years of alfalfa. Instead of expansive
monocultures, they break up their 620 acres into about 45 fields,
letting topography decide how each field is divided. If their light
infestations of corn borers drop a few ears of corn onto the ground,
their cattle glean them after harvest. “Most conventional
farmers continue to tear out their fences,” says Rosmann.
“They don’t have anything running on their fields to
pick up the fallen grain. It’s wasted on most farms. That’s
ridiculous.”
Livestock enrich soils
If he had to offer just one reason why his farming system is so
resilient, Rosmann would say it’s his healthy soils. He beds
his livestock in oat, rye and barley straw — his hogs are
treated to the Swedish deep-bedding system of 2-foot-thick straw
— then composts the straw with their manure. He feeds his
soils every cubic inch of that compost and tills his fields very
minimally. For example, he plants his corn and soybeans into ridges
and turns those fields under only after the rotation’s third
year.
“I think our soil biology is balanced and that the bacteria,
fungi and other microorganisms really help us out,” he says.
“They must be helping our productivity and breaking our disease
and insect cycles.”
Indeed, the Rosmanns have only used one insecticide in their corn
and soybeans in the past 20 years — Bacillus thuringiensis
(Bt) against corn borers — but the insects didn’t affect
yields that year anyway and the Rosmanns haven’t used the
product since. “We try to keep our input costs down. As long
as our yields are not being compromised, why purchase inputs?”
he asks.
Rosmann controls the aphids and leafhoppers in his alfalfa by harvesting
earlier when possible. That decreases production, but he can “put
up with it.” He also plants orchard grass with alfalfa, which
discourages some pests.
Besides soil health, the Rosmanns control crop diseases with resistant
varieties. They shop aggressively for disease resistance, but they’re
becoming discouraged. No resistance is currently available to prevent
the beetle-transmitted seed staining that sometimes sends their
soybeans to feed markets rather than to Japanese tofu buyers. “There’s
very little public plant breeding going on right now,” says
Rosmann. “The interest is in biotechnology and that’s
where the dollars are going, sad to say.”
His ridge-tilled fields are much cleaner than conventionally tilled
fields, with only one-seventh to one-tenth as many weeds. Early
tillage, rotary hoeing after planting and cultivation destroy most
of the weeds in Rosmann’s other fields. The rest of his weeds
he simply lives with, peaceably and profitably.
Abundant small fields foster diverse practices
Rosmann Family Farms has several advantages many other farms don’t:
although they used pesticides for about 10 years during the 1960s
and 1970s, the family never abandoned its mixed crop-livestock approach
nor its generous crop rotations. In addition, the Rosmanns’
600-plus acres give them exceptional flexibility — and protection.
“We have such a diversity of fields in different locations
that we generally don’t have problems in all of our fields
at once — just a portion of a field.”
The Rosmanns’ practices are as diverse as their crops. They
rotate some of their crop fields into grass-legume pastures, especially
if those fields are building up unacceptable levels of weeds. They
use cover crops in the corn they plant for silage but not in other
corn fields. They rotate their grazing as well as their crops, thereby
improving their pasture productivity and pest control. To provide
feed for their cattle from mid-September until late fall, when corn
stalks become available, they also follow barley and oats with turnips,
rye and hairy vetch in mid-July.
The Rosmanns have been evaluating their individual practices with
on-farm research trials for 15 years. They know what contributes
to yield improvements and what doesn’t but they haven’t
precisely pinpointed cause and effect — or whether interactions,
rather than discrete practices, produce crop and soil benefits.
“There’s no doubt, absolutely no doubt, that our approach
is better for the environment and for us,” Rosmann says. “But
we just plain need research — on-farm systems research —
to answer questions on farms like ours.”
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