In-row cultivation is the last piece in effective
non-chemical weed control on an organic farm. In many ways, cultivation
is the ‘crown jewel’; it is here where the skill, ability,
observation and timing of a good operator makes or breaks the effort
(much more so than the choice of any particular piece of equipment).
Successful organic weed control is the sum of all operations and
cultural management. The purpose of the cultural methods (crop rotation,
soil fertility management, sanitation, good seed, cover crops, etc.)
and early season weed control (blind cultivation) is to achieve
the greatest possible crop-weed size differential, especially when
there are many acres to be cultivated. The last stage, in-row cultivation,
is the final performance in the whole package of organic weed control
From the very start, it is important to consider in-row cultivation
as a ‘cleanup’ procedure, not as the primary weed control.
Well-timed early weed control is absolutely essential to reduce
the size of the weed population before it becomes a threat to the
crop. Even with a good job of blind cultivation, there are usually
some escapes (weed seeds that get away and resprout), and, especially
when wet weather prevents proper timing, there may be lots of escapes.
Subsequent in-row cultivation is then necessary to provide clean,
When it is necessary to in-row cultivate crops that are very small,
it is impossible to do a good job on more than a few acres per day.
Weeders allow delaying the first cultivation until the crop is large
enough to cultivate deeply and rapidly. Many organic farmers don’t
have weeders, don’t have the right weeders, or don’t
know how to operate them to get optimum weed control. The first
two articles in this series describe basic weed control principles
and blind cultivation techniques and equipment.
Cultivation also provides many other beneficial effects far beyond
the weeds. Indeed, cultivation is very important for aerating the
soil, stimulating crop root growth, conserving soil moisture, and
providing insulation from the hot sun with a loose, dry soil mulch.
Few conventional farmers who cultivate their crops spend much time
adjusting their cultivators. Herbicides take care of most of the
weeds, and skilled cultivator operators are hard to find. Many conventional
farmers feel that if they can keep the machine between the rows
and avoid taking out too much crop, then they can ‘cultivate’.
This careless approach will not work on organic farms. Indeed, we
prefer not even to consider that type of field operation ‘cultivation’
at all. Getting the weeds between the rows is the easy part! The
real art and skill of cultivating is whether you can also get the
weeds within the row without excessively damaging the crop plants.
Timing is everything
When the crop rows are clearly visible and the corn plants are
8 to 10 inches tall, or soybeans are in the third trifoliate stage,
it is time to begin in-row cultivation. On most New York organic
grain farms, usually two cultivation passes are required. The first
pass is the most critical to determine the season’s weed control,
but the second pass is often necessary to eliminate the weeds that
were stimulated to grow by the first cultivation, to ‘hill
up’ the crop, and to further aerate the soil.
The stage of the weeds and the weather usually dictate how we time
our cultivations. The period of greatest vulnerability for most
weeds comes at a different time after planting than that of the
crop plants. Because crop seeds are generally large and are planted
deeper than most weed seeds, their window of maximum vulnerability
mismatches that of the weeds. We have to take this difference into
account when developing our weed control strategy.
The vulnerability of plants to mechanical disturbance goes through
a predictable cycle, starting with a seed that has not yet started
to germinate. At that stage, seeds are virtually indestructible
by anything other than biological activity. Until a seed imbibes
water and begins to grow, weeders and cultivators have little effect.
A seedling is most vulnerable from the time it germinates until
after the plant has fully emerged from the soil. Once the cotyledons
are fully extended and true leaves begin to develop, the seedling
again becomes harder to injure. The exact timing of these stages
varies between species; generally, once plants are past the unifoliate
stage, most seedlings are much more difficult to damage.
Timing is indeed everything. Unfortunately, knowing the correct
timing and being able move forward are not always the same thing
because of challenging weather conditions. Often, we have to do
the best we can; by combining the effects of two blind cultivation
passes with one to two in-row cultivation passes, we have much more
flexibility with sub-optimal conditions (and usually this results
in good weed control). This is an important point to make, since
there is an oft-repeated fallacy out there that organic farmers
have to cultivate many, many times during a season for adequate
weed control. This is not true! It is the timing and skill with
which the operations are performed that is most critical, not the
number of passes made. If everything else is done right, and if
blind cultivation is timed correctly with the right equipment, one
to two passes with a row cultivator should be sufficient for good
weed control in organic row crops.
Badly timed weedings can actually make the weeds worse. Making
a large number of poorly timed or poorly executed passes will result
in failure, no matter how many trips are made over the field.
When the first blind cultivation is timed just right, the weeders
can be run very aggressively and will achieve almost complete control
over the first flush of weeds. When this happens, the second blind
cultivation can wait until the crop is large enough to allow another
aggressive weeding. However, if our first blind cultivation leaves
too many escapes or if the first weeding fails to sufficiently decrease
the second flush of weeds, we may have to do our second weeding
before we really want to and then may have to come in with the cultivator
before the crop plants are really big enough. Cultivating crops
that are too small is slow, difficult and requires much fatiguing
concentration to avoid injuring the crop plants.
It is important to remember that whenever soil is disturbed, a
new flush of weeds will be stimulated to germinate. Fortunately,
these later weeds are much easier to control, but they still must
be considered in the timing of cultivations and weeding operations.
Tines have changed
Most cultivators built in recent years were not well-designed
to control weeds in the row. While it is sometimes possible to do
a reasonably good job with a modern rear-mounted cultivator, when
the conditions are difficult or weeds are heavy, the shovels next
to the row can’t be adjusted with enough precision nor can
it be operated close enough to the row to take out the in-row weeds.
Front-mounted or belly-mounted cultivators, or pusher cultivators
on bi-directional tractors, are far easier to keep on the row and
work close enough to the crop plants. The operator needs to be able
to easily see all of the cultivator shovels. Carefully watching
the soil flowing around the front cultivator shovels and crop plants
helps the operator to keep the shovels adjusted precisely where
they need to be. It is important to continually adjust speed and
down-pressure on the go to respond to variations in soil conditions
across the field and to always keep the action of the cultivator
as aggressive as possible without excessive crop damage. This is
not possible when the operator can’t look at the cultivator
while steering the tractor.
Danish or S-tine teeth will allow the greatest operating speed,
they are not easily damaged by rocks, they will handle the most
crop residue without plugging and they are relatively inexpensive,
but they do not penetrate as well in hard soil and large-rooted
weeds may slip around the flexible teeth, thereby avoiding damage.
When this happens, putting on narrower shovels will make them penetrate
deeper and give better control. Of different types of cultivator
teeth, the operator has the least control over the action of the
flexible Danish tine teeth.
C-shank cultivator teeth are more rigid and give the operator better
control over the action of the shovels. These may be the best teeth
for hard or rocky soil and for heavy infestations of quackgrass
and other weeds with underground rhizomes. They are less likely
to plug in grassy conditions than trip shanks but much better able
to take out large weeds than Danish tines.
Trip-shank teeth are the most rigid and allow for the slowest progress,
but they give the operator superior weed control and adjustment
ability. These are also the most expensive, large rocks can break
the trip-shanks, and it takes a more experienced operator to make
the necessary adjustments to get the full benefit of trip-shank
There are many different types and widths of points that can be
put on the different cultivator teeth. Danish tine cultivator teeth
offer the least opportunities to vary point type, while trip-shank
teeth offer the greatest choice. The most versatile type of points
are probably half sweeps next to the row and full sweeps between
the row. Each type of point works best under specific conditions
and on certain weed species. For example, a type of point called
a ‘beet knife’ is particularly effective on nutsedge.
Narrow spikes may sometimes be used to advantage to aerate waterlogged
We use a double cultivator arrangement, with trip-shanks on the
front cultivator and half sweeps next to the row to get good weed
control within and immediately next to the row. The rear-mounted
cultivator, which has C-shank teeth with full sweeps, covers the
between-row area. While this combination is slower than a single
Danish tine cultivator, it gives excellent control of most types
of weeds, even under an unfavorable crop/weed size differential.
Other New York organic farmers have had success with rear-mounted
Danish tine cultivators with 5 shanks and 2 1/2-inch duck feet points
between each row. If the ground is hard or there is a quackgrass
problem, 1-inch spikes angled forward to dig deeper can be used.
There are as many ‘right’ ways to set a cultivator
as there are farmers who can get their fields clean of weeds. Every
farmer who is good at cultivating develops their own unique combination
of equipment, settings and special ‘tricks’ that are
especially well-suited to the soils, crops, and conditions found
on that farm. No two farmers will do the job exactly alike, yet
each one can be a master in his own right. Until the late 1940s,
cultivating was a skill that every farmer had to possess. The skill
was passed down from one generation to the next. Every community
had ‘good’ farmers who could be called upon for advice
when you weren’t quite getting the weeds (or for any other
problem that you might encounter).
Our communities have lost countless farmers who held this important
knowledge with no one to pass it on to. Our mentor is an older farmer
named Clifford Petersen. He set a very high standard and has no
tolerance for weedy fields. He often told us that when his son complained
that it took him too long to get the cultivator adjusted right,
he would say “If you don’t think you’ve got time
to do the job right, think about this: Every weed you miss now is
one you will go back and pull!” It took Klaas three years
before he could cultivate a field well enough to win a compliment
from Cliff. Cliff often said that he couldn’t tell someone
how to cultivate right, he had to show it.
However, this attention to detail and perfection must be balanced
with a view of the whole farm and an honest assessment of how much
time it will take to cover all the acres adequately. Taking too
much time to get every last weed in one field may make it impossible
to cover all the rest of the acres on time. It’s important
to keep the whole crop in perspective and not spend too much time
making the first few fields immaculate. You also have to know when
to stop and say you have done your best. Tractor operations after
canopy closing will usually crush and tear crop plants excessively
and may be of no further benefit, as shade from crop leaves will
kill weeds trapped under the canopy.
If at all possible, it really helps to work with an experienced
farmer to learn to evaluate how the soil should flow past the cultivator
teeth, how much side pressure on the row is best, how much dirt
should be pushed into the row to bury the weeds, how to make the
proper adjustments, and how hard you can treat the crop without
hurting it. The real art of cultivating is learning how to make
the right observations and then figuring out how to match those
observations to making appropriate—and changing—adjustments.
There is a big advantage in being able to get on a perfectly adjusted
cultivator when you start out and to see how the soil flows when
a real master has set the shovels to match the crop and soil conditions.
As adjustments are needed, it is much easier make the right ones
when you have seen what ‘working right’ looks like.
Once we know exactly how we want the machine to achieve, it is much
easier to get and keep it there.
Our 16 year old son Peter has been cultivating on our farm for
the past four years. Last summer, he taught his friend Shawn to
cultivate. The two of them covered many acres together, the camaraderie,
cooperation and their iPods keeping boredom and monotony to a minimum.
Peter’s cultivation experience has been gained during the
past five excessively wet years; through these tough conditions,
he has learned to achieve acceptable weed control even when it is
very difficult to do anything ‘right’.
When soil is very dry, it is tempting to run the cultivator shallower
to ‘save’ moisture or to stop cultivating altogether,
because corn curls right after it is cultivated when in the air
is dry. Don’t give in to this temptation! Remember that weeds
can push back up out of dry soil unless they are buried fairly deep.
Escaped weeds are far more damaging to crop yield in dry weather
than when there’s sufficient rain. The soil that the cultivator
hills up around the row provides a dry mulch and stops water from
being brought to the surface and lost by capillary action. Soil
moisture in the hill is much higher than in uncultivated soil, and
the crop grows far more roots in the loose soil of the hill than
when the soil is left uncultivated.
Conventional wisdom says that cultivating deep and disturbing roots
in dry soil hurts the crop. We have never seen any evidence to support
this assumption. We find that new roots grow quickly into the loose
soil left by cultivator shovels and the crop responds with a spurt
of growth. Many organic farmers say that a pass with the cultivator
has the same effect on the crop in dry weather as a half inch of
Adjusting to change
There are many adjustments that can be made while cultivating
to match the effect of the machine to the conditions and needs.
Choosing the appropriate adjustments is not easy to summarize because
conditions constantly change, across the field, in different crops,
in different soils, even over the course of a day as the weather
and moisture conditions change.
In general, there are five main cultivator adjustments possible:
- tractor speed
- angle of the shovels, laterally and horizontally to the row
- depth of the shovels
- down pressure on the gangs, on cultivators with springs
- distance of the shovels from the row
Relatively little adjustment is possible with Danish tines other
than varying speed and depth and by changing the type of the points.
With C-shanks, it is possible to change the angle to the soil and
to the row slightly, but because they are springs, this adjustment
changes in the soil as the cultivator moves. This is not a major
problem when the cultivator is set deep and working between the
rows, but it limits the success of controlling weeds within the
rows. Trip-shanks allow wide adjustment of the angle of the points,
both to the row and to the soil.
Depth of the point is also easily adjusted. Because trip-shanks
are rigid, the adjustments remain constant while cultivating. For
example, by twisting the shank toward the row, a much greater amount
of soil will be pushed into the row. Conversely, by twisting the
shank away from the row, the soil thrown into the row is reduced.
Changing the angle of the point to the soil can adjust for hard
or soft soil. Under the right soil conditions, setting the points
at an extreme angle to the soil can create a bulldozer effect, squeezing
the crop row tightly with soil and thereby killing many weeds growing
between the crop plants (and burying the rest).
Peter says that it is very important to have a well-equipped toolbox
on the tractor, complete with all the sizes of wrenches you might
need, along with Vise Grips, hammers and spare shovels. This permits
in-field adjustment and repair, saving considerable amounts of time
and aggravation. Usually, we try to avoid cultivating in overly
wet conditions. When weeks of nonstop rain come at critical times
of the year, we sometimes have to go into very wet fields to save
the crop. Having a log chain along can be a real convenience during
the wet, muddy summers we have known recently.
When cultivating, Peter tries to drive as fast as he can without
damaging the crop. This aggressive cultivating takes out the most
weeds and, when done well, does little damage to the crop. Higher
speed also throws up more of a hill in the row, which can stimulate
a greater amount of axillary rooting (especially in corn) and can
be more effective in conserving soil moisture. Peter feels that
one of the biggest challenges is to correctly identify the ‘guess
rows’, or the end rows of the planter where the spacing can
vary. Guess rows are called by different names in other parts of
the country. If these rows are not correctly accounted for, the
cultivator will take out crop.
Peter is also careful to do daily preventative maintenance before
starting each day, thoroughly servicing both the tractors and the
cultivators. He and Shawn make sure that all the grease fittings
are filled, all the joints are tightened, and all parts are in proper
alignment before they begin each morning. Peter also takes mental
notes on each field while cultivating, noticing where there are
special weed problems or conditions, and he regularly enters these
observations into the master field notebook.
Peter has noticed that soil conditions really affect the ease and
effectiveness of cultivation. When soil has had a chance to dry
out gradually after a rain, the soil is looser and there are substantially
fewer lumps, which allows for greater cultivator speed and a larger
hill. Conversely, if the soil is wet, slabby or when the surface
dries too fast after a rain, soil lumps or soil ribbons (‘turds’
in farmer slang) develop and roll onto the plants, doing more crop
damage and requiring the cultivator to go much more slowly. If you
have to cultivate in wet conditions, twisting a piece of wire around
the shovel can help break up the slabs of dirt.
Another logical but often-overlooked point in successful cultivation,
was suggested to us by Cliff Peterson. For the second cultivation
in a field, he recommends driving the opposite direction on each
row. It is important to remember the pattern of the first cultivation
and reverse the direction for the second cultivation. This can get
weeds that were not fully removed in the first cultivation and can
compensate for gaps in cultivator coverage.
Plan on spending a lot of time when you first get out in the field,
adjusting the cultivator to get it to work right for the particular
field conditions. As Cliff told Klaas when we were starting out,
“‘Almost’ isn’t good enough!” Don’t
be satisfied with ‘almost’! In most cases, the first
cultivation pass ‘makes or breaks it’; the results of
the first pass will usually determine whether you are going to have
a clean field or not. If you miss the weeds in the row the first
time, cultivating more often later in the season will not make up
Adjustments will need to be done continuously through the day as
soil moisture and field conditions change and as shovels wear or
go out of adjustment. All rows need to be watched for adjustment
needs. As you move along, watch all the rows, don’t just lock
in on only one row. If you don’t watch all the rows, you can
go along quite a ways—and can do lots of crop damage and miss
lots of weeds—before you realize something is wrong.
It is essential to really focus on the rows and the job while cultivating
because even a slight drifting in one row can rapidly result in
large sections of the corn or bean row being very effectively hoed
out. For this and numerous other reasons, we don’t like to
use cab tractors to cultivate, because we can better see the rows
and the cultivators—and respond must faster—if we are
not so isolated. However, we have installed canopies on all the
cultivating tractors for operator comfort and safety.
Cultivating can be a very hot, boring job, especially when the
crop plants are small. For the sake of the operator’s health
and attention span—and the health of the crop—it makes
good sense bring a water bottle, and to stop if you get sleepy.
Staying alert is important. This is both for the sake of safety
and for doing a decent job of cultivating. We’ll be the first
to admit that cultivating can be very monotonous. The ‘glamour’
of cultivating is much more in the theory and the results than in
the actual doing. Stopping for 10 or 20 minutes to nap in the shade
is time well-spent if you are having trouble staying alert. Having
a snack and some caffeinated beverage can help, as can listening
to music or a good ‘book on tape’ on a head-set cassette
player. Carry a cell phone if possible to call for repair parts,
a snack, or relief when needed.
Just a reminder—alcohol and gasoline don’t mix. Our
community has an oft-repeated story of a farmer who didn’t
believe this to be true and drove his cultivator over the edge of
a deep gully twice (with trees fortunately catching the very relaxed
farmer and his tractor). Another local farmer can gauge which of
his men stayed out too late the night before by the number of ‘lightning
strikes’ in the newly cultivated rows the next day.
Icing on the cake
Our friends Eric and Ann Nordell, who farm about 7 acres of market
vegetables with horses in northern Pennsylvania, have done such
a good job of cultural weed control that they don’t really
need to cultivate to get rid of weeds. Their soil is essentially
weed seed free, due to conscientious use of cover crops, mulches,
and rotation. Yet the Nordells still cultivate their crops to achieve
the other important benefits of cultivating. Eric says they cover
crop for weed control and cultivate to control moisture.
We agree and have noticed how crops will green up and ‘jump’,
growing noticeably taller soon after each cultivation. Loosening
and letting air into the soil keeps it aerobic and stimulates soil
organisms. It also stimulates nitrogen mineralization and nutrient
cycling in the soil, and the CO2 that escapes from loose, freshly
cultivated soil enhances crop growth.
In-row cultivation is in many ways the heart of what makes an organic
farm productive and successful, especially on grain farms where
weeds are the primary challenge. However, like the heart of an organism,
cultivation works best when it is part of a complex and well-coordinated
choreography of soil improvement, crop rotation, cultural methods,
and other mechanical weed control operations, along with cooperation
with the weather.
When all that happens, the healthy weed-free rows of organic crops
are indeed a beautiful sight.