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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
strategies.
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, productive fields.
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 teeth.
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 soil.
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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.
Cultivating technique
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 rain.
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.
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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 for it.
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.  |
