ROCK HILL, S.C. --Your crop rotation and cover
crops can do a lot for you -- and you had better be sure they do
That was the messageto organic farmers who traveled to Rock Hill
SC in early November to attend the annual Sustainable Agriculture
Conference sponsored by the Carolina Farm Stewardship Association
The group’s 18th annual conference had a cluster of workshops
on aspects of managing selected crops to improve soil fertility,
increase water retention, enhance soil organic matter, manage disease
and insects and keep down weeds for no-till transplanting.
Farm Stewardship Association (CFSA)
CFSA is a membership organization of more than 800 farmers,
processors, gardeners, businesses and individuals in
North and South Carolina who are committed to sustainable
agriculture and the development of locally-based, organic
Founded: In 1979 by a group of farmers,
gardeners and consumers to support each other in their
efforts to foster the growth and distribution of organic
food in the Carolinas.
Mail: PO Box 448, Pittsboro, NC 27312
13 Hillsborough Street Suites 3 & 8, Pittsboro,
Contact info: Tony Kleese
(site under re-construction, click “Farmer Resources”)
What is crop rotation? Jim Riddle, an organic certification expert
from Minnesota, defined it for a workshop at the conference as the
practice of alternating the crops grown on a specific field in a
planned pattern or sequence in successive crop years so that crops
of the same species, or family, are separated year-by-year by other
crops in a beneficial way.
One basic rotation might be to plant a rye cover crop right after
corn in a corn/soybean rotation. The rye will scavenge residual
nitrogen and provide ground cover in the fall and over winter. When
it is killed in early spring, the rye provides a water-conserving
mulch and suppresses early-season weeds for the following soybean
A subsequent cover-cropping step could be planting hairy vetch
(a winter annual legume) behind the soybeans to provide nitrogen
for corn the following spring. (For more on the basics of rotation,
see “Overview of cover crops and green manures” in the
“Fundamentals of Sustainable Agriculture” series at
An optimal crop rotation for organic grain production, said Riddle,
–Maintain or improve the organic matter level of the soil.
–Provide for pest management.
–Make it possible to manage deficient or excess plant nutrients.
–Improve erosion control.
To make a crop rotation work, find the highest return for each
cash crop included. Determine if a cover crop can be grown on contract
or can be fed to your livestock. Find out if seed is available when
you need it, and if can you meet any of the market’s quality
You also want to look for special agronomic characteristics in
rotation crops that are serving essentially as cover crops, i.e.
have their primary value in benefiting the soil or the next crop,
rather than to be harvested and sold. The ideal cover crop would
germinate and emerge fast, compete effectively in the field with
other plants and weeds, tolerate adverse climatic and soil conditions,
suppress easily and be inexpensive to establish.
You are not likely to find a cover crop with all these characteristics,
Riddle explained. You must set priorities, determine the top priorities
for your cover crop and then choose an appropriate species. Be sure
to find out which species do well in your region.
Selecting crops for insect control
Rotation and cover crops definitely have a role to play in insect
control, said Debbie Roos, an agricultural extension agent from
Chatham County NC who spoke on organic insect management.
As insects overwinter in soil and debris, they will re-infest the
new crop if it is susceptible. Pest populations can build up. The
solution is to rotate with non-susceptible crops so that pests have
no food or shelter. Leave as much time as possible between related
crops to make conditions difficult for the pests.
Crop rotation is not effective for controlling pests with a broad
host range. There are three questions to ask yourself, Roos said:
-- How long can the pest persist in the field without any host?
-- Can it invade from other areas?
--Does it survive well on other hosts when your crop is not present?
The more holistic but less precise approach is to use good bugs
to fight the pest varieties. Here, cover crops can provide a valuable
habitat and food source for beneficials, allowing their populations
to build up early in the season before the emergence of pests. Using
companion plants in a sustainable program has been suggested as
a pest control strategy. This approach could involve attractant
(trap) crops like caraway, fennel and hyssop. There are thought
to be some repellent crops: catnip and tansy are said by some to
repel aphids, while artemisia is said to repel flea beetles. For
Roos, the value of all this remains rather vague. In some situations,
alleged companion plants have been shown to actually increase pest
"There are lots of recommendations about companion crops out
there with little scientific evidence on a field scale," said
Roos. "We need more study before recommending." Growing
a diverse mixture of crops, in alternate rows across a field, helps
attract beneficials and impede pests. Roos is conducting on-farm
research to learn more about how farmers may benefit from beneficial
When your cover crop becomes a weed
Any cover crop species will work better with some crops than with
others. Kenny Haines of Looking Back Farms in Tyner NC had good
success with a rye/hairy vetch cover crop back when he was growing
mainly fruits and vegetables. But then he started planting grains,
and the hardseeded vetch presented a problem.
“It’s cheap and grows vigorously, but it can easily
go to seed and come up in your wheat,” said Haines. “For
that reason, we have had to get away from vetch.” Much of
his land is in a rotation of corn followed by wheat and soybeans,
though rye/vetch still has an occasional use if Haines can place
it well before wheat. He also grows watermelons occasionally in
Some of the participants in the discussion suggested crimson clover,
sweet clover or red clover as substitutes for the vetch.
Haines likes to till as little as he can, but because of a problem
with the cover crop, he is reluctant to go 100 percent no till.
“If you no-till soybeans into wheat straw, you have no defense
if weeds come up,” he said. “If I plow [on the other
hand], I have a range of cultivators to choose from to do the job.”
New varieties make small grains a better
If you need a small-grain crop in a rotation, either as a cover
crop or cash crop, the most important step is to choose the right
grain and the most suitable variety. There are varieties of all
the Southeast’s major feed grains -- wheat, oats, barley,
triticale and rye – that will all do well in sustainable agriculture,
said Paul Murphy, an NC State University plant breeder.
That is in part because breeding programs have followed priorities
that are as important to organic agriculture as they are to conventional
farming. “Traditionally in this area, all the grains have
been considered low-input crops,” said Murphy. “Farmers
anticipate resistance to all the important pests in the varieties
that are available, since they don’t want to have to treat
for them.” That means there are plenty of varieties for the
organic/sustainable farmer to choose from.
“Good yield and quality should be factors in a variety choice,”
said Murphy. “But also take into consideration resistance
to powdery mildew, Hessian fly and leaf rust. If you select carefully
among the numerous varieties available, you will be able to get
that resistance with the other characteristics that you need."
Wheat: Among wheat varieties, a new introduction
called “NC Neuse” (after the Neuse River) could prove
to be a good choice in organic programs, said Murphy. It is resistant
to powdery mildew and leaf rust and is also moderately resistant
to fusarium head blight and Hessian fly.
There may well be a benefit to choosing a hard red winter wheat
variety rather than a soft red winter wheat, the type traditionally
grown in the south, said Murphy. Research at NC State on identification
of suitable hard wheats is progressing rapidly, and recommendations
will be available for planting in fall 2004.
Barley: A trend in small-grain breeding that could
provide some tools for sustainable agriculture growers is the recently
developed breeding goal of “hull-less” seedheads. One
such variety, a barley called “Doyce,” should be available
in 2004 from Virginia Tech. It grows and looks like regular barley
until it is mature. During combining, the hulls separate from the
grain. It has attracted some interest as a high-energy animal feed
and also as feedstock for ethanol production.
Oats: Thishe new characteristic has not been confined
to barley. A new hull-less variety of oat called “NC Hulless”
is also available. Its hulls are threshed off the seed so you end
up with a higher energy, higher protein feed. “This oat has
a role to play in hog, poultry and perhaps even fish farming,”
said Murphy. It could find a place in horse-feeding programs, as
Triticale: This grain -- a cross between wheat
and rye -- has inherent insect and disease resistance that might
make it a good fit in sustainable agriculture. “We have observed
in our breeding nurseries that triticale has high levels of disease-
and insect resistance and drought tolerance,” said Murphy.
“Its grain has a high-quality protein that makes it suitable
for hog and poultry feed, and many cultivars produce abundant leafy
growth in late winter and early spring with potential for grazing
or silage production.
“It performs well in the southeast and is relatively easy
to produce. It has a niche, but as with hull-less barley and oats,
make sure you have a market for it before you grow it,” he
cautioned. N.C. State University released its first triticale cultivar,
“Arcia,” in 2001.
Rye: Rye is popular as a cover crop because it
has the highest level of allelopathy – weed suppression –
of any of the common small grains.
“There is a danger, however, if you are planting a small-seeded
crop like lettuce behind rye,” said Murphy. “Rye interferes
with weed-seed germination, and so it might interfere with a small-
seeded crop. Transplants would face less of a risk.”
Chris Bickers is a freelance writer-photographer in Raleigh,