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THE MOST COMMONLY ASKED QUESTIONS ABOUT CROSS SLOT™ NO-TILLAGE
SLOT SHAPE
1. What is different about Cross Slot™ openers?
Cross Slot openers create horizontal soil slots (for seed and
fertilizer) whereas most other openers create either vertical or
slanted slots and most are for seed only.
2. What is the significance of Cross Slot creating horizontal slots?
Vertical, and even slanted slots are very difficult to close,
especially in damp soils. With horizontal slots the seed is tucked
under a horizontal flap of soil at the time that the slot is
created, ensuring the seed is always covered.
SLOT MICRO-ENVIRONMENT IN DRY SOILS
3. Do horizontal slots have any other advantages?
Yes, several. They ensure that the seed micro-environment can be
controlled almost regardless of soil conditions, and they permit
fertilizer to be placed in bands that are separated horizontally
from the seed.
4. What is so special about controlling the seed micro-environment.
Isn't getting good seed-soil contact enough?
In short, no! Seed-soil contact is often not enough under no-tillage
and is why no-tillage often fails compared with tillage. On the
other hand it is also why no-tillage, undertaken with Cross Slot
openers can be more successful than tillage.
5. Please explain.
Soil that is not tilled has an atmosphere within its pore spaces of
100% relative humidity. Germination of seeds is greatly assisted by
this humid soil atmosphere. In some cases the humidity alone is
capable of germinating seeds by itself without any soil-seed contact
at all. But the relative humidity level needs to be at least 90% to
do this.
6. Does this mean soil-seed contact plays no part at all with
no-tillage?
No! Seeds will take up water in both liquid and vapour (humidity)
forms. Seed-soil contact is still important to maximize the liquid
uptake, but the availability of vapour moisture in Cross Slot slots
gives no-tilled soils an added resource to germinate seeds.
7. Does this mean that seeds sown with Cross Slot openers do not
actually have to be in contact with wet soil?
Yes! It means exactly that. Provided there is a good mulch cover of
surface residues it is not necessary to actually place the seed in
damp soil. Close to it will be sufficient for the humidity to do the
rest.
8. In such circumstances will germination be as fast as if the seed
had been in damp soil?
No! Relying on humidity alone (or even as the predominant mechanism)
for germination will certainly delay germination since uptake of
vapour water by seeds is slower than uptake of liquid water. But it
will occur nonetheless.
9. Don't tilled soils also have such soil humidity?
No! The tillage process aerates the soil so much that soil humidity
escapes to the atmosphere and finds a new lower level that seldom
approaches even 90% (let alone 100%) except when it rains. Seeds
sown into tilled soils therefore mostly rely on absorbing liquid
water from the soil and this is influenced greatly by soil-seed
contact.
10. If that is the case why is no-tillage not always better than
tillage?
Because not all no-tillage openers (and the soil slots they create)
are capable of harnessing the soil's humidity. Nor are many of them
capable of even creating good soil-seed contact.
11. Please explain the role of openers in relation to retaining soil
humidity.
Although undisturbed soil, especially if it is covered with crop
residue (which is the cornerstone of no-tillage) is always at 100%
relative humidity, there is one disturbed zone in each otherwise
undisturbed soil that is capable of loosing humidity. This is the
slot zone created by the openers as they pass through the ground
sowing seed and perhaps fertilizer. Therefore it is important that
no-tillage openers create their slots in a manner that minimizes
loss of humidity from the slot zone itself while at the same time
ensuring the seed gets good contact with the soil.
12. In what ways do different no-tillage openers vary in their
abilities to retain soil humidity?
The biggest issue is how the slot is closed. With horizontal slots
(Cross Slot) two flaps of soil are raised by the wings of the opener
as it travels along, creating two horizontal shelves, one each side
of a central disc. Seed and fertilizer are placed separately on each
of these shelves and the flaps of soil are then folded back over the
seed and fertilizer. If the flaps of soil are also covered with crop
residue this traps the humidity under the flaps.
With vertical slots there are no horizontal soil flaps to be folded
back over the seed. The best that can be done is to try to squeeze
the sidewalls back together so as to wedge the seed between these
walls. But even then the best that will happen is that this will
assist soil-seed contact and ensure water is taken up in its liquid
form. Vapour water plays no part in germination in vertical
no-tillage slots.
With slanted slots there may be a partial slanted soil flap created.
If so this will trap some vapour water but it is not nearly as
effective as horizontal slots in this respect.
13. How do we know this is not just all sales talk?
Because it is has been the subject of numerous scientific studies
that are reported in the international scientific literature and
were subjected to peer review by other international scientists over
a period of 30 years. No-one has ever challenged these findings,
which are also the subject of an international textbook on the
interactions between soils, seeds and no-tillage openers.
14. Even although it would seem to be impractical, could you get the
same effect from vertical slots by placing strips of say plastic
over them?
Scientists tried this. Even although they found that the slot
atmosphere did indeed remain at around 100% relative humidity, they
also found fungal growth in the anaerobic atmosphere of the
plastic-covered slots. From this they concluded that by ensuring
soil gets covered with dead plant residues, nature has always
provided a medium that retains moisture vapour but also lets the
soil breath. Plastic cannot duplicate both functions. Cross Slot
slots simply duplicate what nature has always done, so it is no
surprise that seeds and plants respond favourably.
It is not an accident that most trees flower and then drop their
seeds on the ground before they shed their leaves. The leaves then
land on top of the seeds and create conditions similar to that
created by Cross Slot no-tillage openers. All we are doing is
duplicating nature except that we are choosing the seed type we want
and putting it in rows.
15. What happens to the slot microenvironment if dry soil gets in
contact with the seed?
With some angled disc openers dry soil can fall into the slot before
the seed, which effectively embeds the seed in dry soil. This cannot
happen with Cross Slot openers since the seed travels down the
inside of the blades, which prevent other soil from falling into the
slot until after the seed has been placed. Even if some dry soil did
eventually fall into Cross Slot slots the high humidity still
ensures that germination will take place.
With other openers the dry soil cushion prevents the seed from
getting access to liquid-phase water.
SLOT SHRINKAGE
16. What happens if the soil shrinks after seeding and the slot
opens up as a result?
Shrinkage of this nature is unavoidable on occasions with all
no-tillage openers. But even although the vertical portion of a
Cross Slot slot may open just as all other slots do, if you place a
small humidity probe down the vertical part of the slot and then
into the horizontal part (as scientists have done) you might find a
low humidity zone in the vertical part but there will be a high
humidity zone under the soil/residue flaps in the horizontal
shelves. Because the seeds are located in this horizontal zone they
remain in a high humidity zone whereas with all other openers it is
difficult to avoid seeds being placed in the low-humidity vertical
zone.
Of course if the soil has adequate liquid moisture anyway, placing
seeds in a low humidity zone may not affect germination because the
seeds may then get their water from contact with the sidewalls of
the slot, regardless of whether these are vertical or horizontal.
The main differences show up as soil conditions move from being damp
(optimum) to dry (sub-optimum). They do not need to move far from
optimum to show differences.
17. But if the seeds are tucked off to one side under a flap of
soil, how do they
emerge?
In circumstances where the central slit of a Cross Slot slot shrinks
open and the seeds are under a flap to one side, the seedlings will
initially grow sideways until they are in the open slit, and then
they will grow vertically. There are many examples and photographs
showing that this is what happens. The end result is a perfectly
healthy plant that would otherwise have died in other no-tilled
slots.
18. But what happens if the soil is loose and friable over the seed?
Firstly if the soil is like this it will probably not shrink much
anyway, so the central slit will not open up. But in these
circumstances most seeds will simply travel up through the overlying
soil and emerge directly above where they were sown rather than take
a pathway up through the central slit.
19. How much difference in seedling emergence rates are we talking
about?
The differences in seedling emergence counts between openers get
bigger as the soil conditions get worse. For example differences of
1,000 to 1,400% between Cross Slot openers and double disc openers
have been reported in the scientific literature with dry soils.
Differences of 20-50% are very common, even when soil conditions are
only slightly sub-optimal. In wet soils differences up to 400% in
favour of Cross Slot openers have been reported for different
reasons.
GERMINATION AND EMERGENCE
20. Does it follow then, that so long as seeds can get an adequate
supply of liquid water there will be no differences between the
various no-tillage slots?
Unfortunately no! There is more to it than that. Experiments have
shown that even if a seed germinates in a vertical slot made in a
dry soil (because it has good contact with the sidewalls of the slot
and is therefore able to take up liquid water) the ability of that
seedling to survive until it emerges from the soil is an even
greater problem in getting a reliable stand under no-tillage.
21. If seeds can germinate in a no-tillage slot, why would they not
also be able to emerge?
Because there is a critical period between germination and emergence
(which lasts several days) during which seedlings must start
collecting water from the soil with their new root systems in order
to (1) remain alive, and (2) give them the resources to push through
the soil and finally emerge. Sub-surface survival (or mortality) of
seedlings is a major determinant of the success or failure of
no-tillage crops.
22. Why do some sub-surface seedlings live while others die in
no-tillage?
Seedlings die when their roots cannot get through the walls of the
slot to collect water from the surrounding undisturbed soil. Unlike
tilled soils, in no-tillage slots there is a disturbed slot zone and
an undisturbed soil zone alongside. The interface between the two
zones in a no-tillage slot is usually the slot wall and is very
distinct. In tilled soils there is no such interface because all of
the soil has been disturbed beforehand and the openers do not create
any major differences between the two areas.
The problem in no-tillage is worst when the slot wall is nearly
vertical, and worse still when it is compacted such as when it is
created by wedging a neat "V" with a double (or triple) disc opener.
It is still a problem with "U" shaped slots created by hoe-type
openers and slanted slots, but is no problem at all with inverted
"T" shaped slots created by Cross Slot openers. In the latter case,
because the sub-surface seedlings are held in an atmosphere of near
100% relative humidity, they do not become stressed while the roots
negotiate the interface between the slot zone and the undisturbed
soil alongside, which is non-compacted and mainly horizontal anyway
and therefore more in line with where the roots want to go (ie
downwards).
23. How long can sub-surface seedlings survive in an inverted "T"
shaped slot before emerging?
Scientists had measured survival times of up to three weeks in very
dry laboratory conditions. But field experience has recorded
survival times up to eight weeks in a dry soil before rain
eventually fell and provided an abundance of water.
24. Is there a limit to the dryness of the soil from which seeds
sown by Cross Slot no-tillage will fail to emerge?
Yes! But it is remarkable just how dry a soil they will tolerate.
Scientists have recorded 50% emergence of wheat seedlings from a
no-tillage soil sown by Cross Slot openers at -12 bar moisture
tension. The moisture tension is a measure of how tightly moisture
is held by the soil particles. A high negative pressure denotes soil
that is drier than a low negative pressure. Minus 15 bar moisture
tension usually defines "permanent wilting point", which is where a
soil is so dry that growing plants will wilt and not recover even if
water is re-applied.
25. Does that mean then that untilled soils have more potential to
stimulate germination and seedling emergence than they have to
sustain plant growth?
Yes! It means exactly that. Even at "permanent wilting point" an
untilled soil will provide an equilibrium relative humidity of 99.8%
in its pore space and this is the key to seed germination and
seedling survival in such soils provided the no-tillage openers are
designed to harness that potential. But a growing plant cannot
harvest water at such a tension. Experiments have shown that while
you can get wheat seedlings to emerge from a soil at -12 bar the
plants died soon after emerging.
Because tilled soils almost never have an equilibrium relative
humidity approaching 100% (except when it is actually raining),
germination must wait until there is sufficient liquid water for the
seeds to absorb and this also ensures there is sufficient water for
the seedling roots to sustain the plant both before and after
emergence.
26. Is there therefore a danger that Cross Slot openers will force
germination from soils that are too dry for the plants to grow in?
That could be argued. But the solution (to redesign Cross Slot
openers so they are less capable of germinating seeds) seems
illogical. In reality it is very seldom that crops fail when sown
with Cross Slot openers into untilled, residue-covered soils. In
fact their ability to tolerate a much wider range of conditions than
other openers is one of the main things that make them superior to
all other no-tillage openers and gives them such a high failsafeness
rating (99%).
SLOT MICROENVIRONMENT IN WET SOILS
27. Are there advantages of Cross Slot openers in wet soils?
Yes! They are equally tolerant of wet soils for entirely different
reasons. And there are further advantages too (see below).
28. In what way are Cross Slot openers superior to other openers in
wet soils?
Scientists have shown that when an inverted "T" (or horizontal)
shaped slot is created in a wet soil, the placement of crop residue
over the slot provides a ready source of food for earthworms, which
actively colonise the slot zone. This in turn leads to an increased
oxygen supply to the seeds because of their tunnelling. Further the
tunnelling also increases the rate of infiltration of rain (or
irrigation) water into deeper layers of the soil.
29. What opener types are worst in wet soils?
Double (or triple) disc type openers, because of their wedging
action, produce sidewall compaction, which discourages earthworm
from colonizing the slot zone. Further, by compacting the soil they
exclude oxygen and push residue down into the slot allowing seed to
become lodged in this residue.
The latter problem is known as hairpinning (because the straw gets
bent over like a hairpin) and is explained elsewhere.
SLOT MICROENVIRONMENT IN RELATION TO SURFACE RESIDUES
30. What is the disadvantage of seed becoming lodged in residue (a
hairpin) pushed down into a no-tilled slot in a wet soil?
The residue decomposes and in so doing creates acetic acid, which
burns the seeds or seedlings, thus reducing emergence counts.
31. Does this not happen with Cross Slot openers too?
The central disc of Cross Slot openers will push residue down into
the vertical slit under certain circumstance. There is no known disc
opener that does not do this. The difference though, is that with
Cross Slot openers the seed is placed off to one side of the
vertical slit on a horizontal shelf. Seeds are never in contact with
the residue. The acetic acid that is produced by decomposition of
the residue is very rapidly broken down by soil microbes. Even a
small amount of physical separation (as little as 10 mm) between the
residue and the seed is effective in preventing seed burn. Only
Cross Slot openers achieve this.
With all other openers (including slanted discs that produce angled
slots) the seed is deposited right into the residue that is tucked
into the slot. So seed burn is inevitable in those circumstance when
and if acetic acid is produced as a result of decomposition.
32. Are there any circumstances in which seed burn will not occur
when residue is pushed into the slot of other openers?
Yes! When the soil is dry and the residue therefore does not readily
decompose. But then the seed may be prevented from having good
seed-soil contact because the residue insulates it from contact with
the slot walls.
So one way or another, unless the seed can be tucked off to one side
of a slot created through heavy residue levels in no-tillage, it
could be at risk in both dry and wet soils. The only time the risk
does not exist with other openers is when soil moisture conditions
are optimal and there is plenty of in-slot oxygen available, but
no-one can guarantee that happening at any time, let alone all of
the time.
33. Does that mean that in optimal soil conditions one would not
expect to see major differences between Cross Slot and other
no-tillage openers?
Sometimes, yes. But seedlings that emerge from Cross Slot slots,
even in optimum conditions, are thought by seed physiologists to be
advantaged because of the relatively small amount of energy they
expend and the lack of stress they encounter in getting to the soil
surface. The high-humidity of Cross Slot slot is thought to have an
important effect in cocooning the seed in a favourable atmosphere
prior to emergence, and thereby influencing crop yield potential
even before the seedlings have emerged from the soil, and even when
plant counts between Cross Slot and other openers are the same due
to favourable conditions. But then seedling emergence is only one
part of the equation anyway.
FERTILIZER PLACEMENT
34. What other things influence crop yield potential?
Another major determinant of crop yield is how well the plants are
fed and this is influenced by fertilizer placement at the time of
sowing.
In a survey of no-tillage experts in the USA in the early 1990's,
all agreed that the single most important feature they would like to
see on no-tillage openers, was the ability to place (band)
fertilizer separately at the time of seeding. Cross Slot openers
provide a facility in this respect that no other design has yet
emulated, let alone surpassed.
35. Don't other no-tillage openers also provide the capability of
separately banding fertilizer at the same time as seed?
Very few. With some designs two openers are married together so one
places seed and the other bands fertilizer, but the combined opener
occupies so much space that this seriously limits how close the sown
rows can be to one another on a drill. In other cases manufacturers
provide two rows of seed and every third row is for fertilizer alone
(known as "skip row"). This has a negative effect on crop yield
because of the disruption to even populations of plants.
In still other designs separate fertilizer banding is achieved by
creating a very large disturbed zone with a tine and splitting the
flow of seed and fertilizer before they reach the ground. But the
amount of soil disturbance such openers create largely negates their
claim to being no-tillage openers. They also have only a limited
ability to avoid blockage with surface residues, which further
prevents them from being used repeatedly in a true no-tillage
environment.
36. Is there anything else special about how Cross Slot openers band
fertilizer?
Yes! Scientists in USA have shown that horizontal banding of seed
and fertilizer under no-tillage produces superior crop yields to
vertical banding. Cross Slot openers specialize in horizontal
banding. In addition, by using optional short and long side blades
on either side of the disc Cross Slot openers can also be made to
produce vertical banding for those who have come to believe that
"deep banding" is the only way.
37. What is wrong with "deep banding" anyway?
One of the biggest mistakes no-tillage growers and machinery
designers can make is to assume that what works in tillage will also
work in no-tillage. Just because "deep banding" (placing fertilizer
up to 75 mm or 3 inches below the seed) seemed to work in tillage
does not mean it works in an untilled soil. In fact there is strong
evidence that such is not the case.
38. How do we know that "deep banding" is not appropriate in
no-tillage?
Because the US Department of Agriculture conducted extensive
independent trials over a three year period comparing Cross Slot
openers (horizontal banding of seed and fertilizer) with Yielder
double disc openers ("deep banding" with vertical separation of seed
and fertilizer in a skip-row configuration). In none of the seven
separate experiments was the crop yield from the Yielder openers
equal to (let alone better than) that from Cross Slot openers. The
average wheat yield advantage over 3 years in favour of Cross Slot
openers was 13%.
Up until that time Yielder openers had shown the best crop yields of
any no-tillage openers then available in the USA.
39. Why can't farmers simply broadcast the fertilizer under
no-tillage in the same way that they often do with tillage?
Because no-tilled soils behave differently than tilled soils when
fertilizer is applied. Untilled soils contain earthworm and old root
channels that the soluble nutrients run preferentially into, which
means that much of the nutrients get diverted away from the small
root zones of new plants sown in rows. In a tilled soil these
channels are broken up by the tillage process and replaced by an
evenly-dispersed artificial pore systems. So fertilizer filters down
more or less evenly in a tilled soil.
Thus it is more important to band fertilizer in no-tillage than in
tillage. Very poor crop responses have been recorded from
broadcasting fertilizer on the surface under no-tillage whereas good
responses are commonly obtained doing the same thing on tilled
soils. The differences have been greater in spring than autumn.
40. If this is so then how is it that pastures, for example, respond
to broadcast fertilizer?
Because pastures contain a labyrinth of mature roots that intercept
all fertilizer that is placed on the ground surface and washed into
the soil by rain, regardless of the presence or absence of earthworm
and old root channels.
41. Given that you can place fertilizer in separate bands with Cross
Slot openers, should growers be using more or less fertilizer when
they no-till with these openers?
With phosphate, potassium, sulphur and micronutrients, use the same
amounts that would be used in tillage. Feel confident about using
micronutrients such as boron that can burn the seed if mixed with
it. It will be separated from (and not burn) the seed with Cross
Slot openers.
With nitrogen it is usual to increase the amount applied at sowing
under no-tillage anyway, compared with tillage. This has nothing to
do with opener design (except that it is not possible to apply any
nitrogen at all with most other no-tillage openers). It is because
under no-tillage generally, the soil microbes use a lot of nitrogen
in decomposing the sprayed weeds and surface residues prior to
seeding. This can result in the young crop becoming nitrogen
deficient for a period. Adding nitrogen fertilizer at seeding
overcomes the short-term deficiency, which ironically corrects
itself later in the growth cycle anyway when the microbes themselves
die and release the nitrogen again.
With tillage, nitrogen is mineralized by the tillage process, which
(1) creates a convenient source of nitrogen for the young plants,
but (2) is achieved by oxidizing some of the organic matter in the
soil and eventually leads to reduced organic matter levels, which in
turn leads to erosion and lower crop yields.
42. Other manufacturers claim to be able to band fertilizer with
their openers. Is this just sales talk?
In the main yes! Other machines may be able to dispense fertilizer
at the same time as seed but it is what happens to it in the soil
that matters. Unless the openers are doubled up (as described above)
it is likely that the seed and fertilizer will become mixed as they
enter the soil. A small amount of mixing is acceptable if the
fertilizer rates are low and special slow-release forms are used
(such as low rates of DAP), but normal fertilizer rates cannot be
safely applied. The problem is further exacerbated by the absence of
loose soil in many no-tillage slots, compared with tillage. Loose
soil otherwise dilutes the fertilizer somewhat.
43. Does the fertilizer banding function of Cross Slot openers
operate in all conditions?
Yes! One of the main features of the horizontal separation action is
that it is equally effective in wet, dry and optimum soils and is
unaffected by the presence or absence of surface residues or stones,
and at forward speeds up to 10 miles/hour (16 kph).
44. Is the fertilizer banding function of Cross Slot openers limited
to dry fertilizer?
No! Both ammonia as a gas and liquid fertilizers can be sown with
Cross Slot openers at the same time as the seed with no detriment.
In fact liquid or gaseous fertilizers can even be sown at the same
time as dry fertilizers using Cross Slot openers.
To keep the wet or gaseous fertilizer from contacting the central
disc (a wet disc is undesirable) the delivery tubes are angled away
from the disc under the soil while dry fertilizer slides down beside
the disc.
SLOT CLOSURE
45. What other functions are unique to Cross Slot openers?
Several. Another important function is controlling closure of the
slot and also seeding depth. With Cross Slot openers both of these
functions are undertaken simultaneously by the press wheels. They
are located close to the seeding zone so they ensure the openers
rise and fall (up to 45 cm or 18 inches if necessary) in harmony
with changes in the soil surface.
But they also fold the soil flaps back over the seed so as to retain
the integrity of a truly horizontal (inverted "T" shaped) slot with
all of its advantages discussed above.
SEEDING DEPTH CONTROL
46. Do Cross Slot openers do anything special as far as depth of
seeding is concerned?
Yes! A further unique function of Cross Slot openers is that the
downforce is controlled very carefully. In this regard the designers
of Cross Slot openers realised at an early stage that when springs
are used to push openers into the ground the downforces alter as the
springs lengthen and shorten. There is no way of completely
overcoming this mechanical shortcoming. The problem is exacerbated
because no-tillage openers are required to travel up and down much
more than openers used in tilled soils because tillage smooths the
soil prior to drilling.
Cross Slot openers are therefore pushed into the ground with
individual hydraulic cylinders that act against one another and are
cushioned by a common source of compressed nitrogen. The main
advantage is that the downforces remain the same regardless of the
position of the opener. So engineers were able to design in an
extraordinary amount of vertical travel (45 cm or 18 inches) for
each opener, which no other known no-tillage opener achieves.
47. Hydraulic rams on each opener sound very complicated and
expensive.
They are neither. The hydraulic rams are also used to lift the
openers off the ground for transportation, which eliminates the
complication and expense of designing lifting mechanisms into drills
and creates more space flexibility within a drill and facilitates
close row spacing. Each Cross Slot opener is, in fact a
self-contained modular unit requiring only to be connected to
hydraulic, seed and fertilizer supply hoses.
48. Are there any other features of hydraulic downforce rams that
are an advantage?
Yes! Because they are all connected to the same source of oil
supply, when one opener rises almost inevitably another opener will
be going down. Thus openers exchange oil between themselves most of
the time, which means that the overall oil pressure does not change
much as the machine proceeds. In any case the overall oil pressure
can be changed by the operator on-the-move, which gives the operator
continuous control over downforces in response to changes in soil
hardness across a field.
Mechanical springs simply cannot do any of these things.
49. Does the system go further than that?
Yes! Individual hydraulic cylinders on each opener also allow the
oil pressure (and thus the downforce) to be constantly monitored and
altered. Cross Slot machines have an electronic monitoring system
(called Auto-Downforce or ADF) that measures the force required to
push the openers into the soil to a given depth and gives the
operator a continuous read-out of this force in the tractor cab.
If the force required for correct penetration increases for example
(because in that part of the field the soil is harder - as is common
with no-tillage since the soil will not have been evened up with
tillage) the operator knows that (1) seeds will be sown too shallow,
and (2) slot closure will be poor.
Conversely if the soil gets softer the openers may be pushed too far
into the ground causing ridging and burying the seed too deeply.
50. What happens then?
One of two things. There are two optional systems an operator can
choose from:
The manual monitoring system allows the operator to change the oil
pressure on-the-move using the tractor's spool valves in the cab
until the reading returns to the pre-set level, thus ensuring that
the pre-set seeding depth remains constant.
Or the automatic monitoring and control system signals the tractor
hydraulic system to automatically make the necessary alterations to
the downforce pressure with no interference from the operator other
than to have set the operating parameters in the first place. This
removes yet another opportunity for operator error and is a major
aid to helping maintain consistent seeding depth under no-tillage.
No other system achieves this degree of accuracy and automation.
51. The system sounds like it is electronically controlled. Is there
a fail-safe back-up in case of failure of the electronics?
Yes! The operator can over-ride the automatic system at any time to
change it either to a manual-monitored system or a fully manual
system in which no monitoring takes place at all.
RESIDUE HANDLING
52. We are told that surface residues are an integral part of how a
Cross Slot opener operates. Will it function in the absence of
residues?
Yes! Without residues the function of retaining soil humidity
suffers somewhat because it is the residues covering the soil flap
that are responsible for retaining much of the soil humidity. But
the sophisticated control of seeding depth, enhanced soil-seed
contact, and fertilizer banding functions still give the opener a
distinct advantage over other no-tillage openers.
53. Are Cross Slot openers of any advantage in tilled soils?
Yes! Their superior seed placement and closing functions together
with fertilizer banding ensure they function very well in tilled
seedbeds. It is not suggested that operators who drill only tilled
soils should equip themselves with Cross Slot openers. They are
probably an "over-kill" for tilled soils. On the other hand they
have no disadvantages in tilled soils either, so they certainly suit
operators who work in both tilled and untilled seedbeds with the
same drill.
54. How well do Cross Slot openers handle heavy residues?
So long as the openers are functioning correctly it is virtually
impossible to block them in heavy residues. They have a unique
method of clearing residues while still retaining the ability to
micro-manage the residues so they finish up back over the slot zone.
They have no problem handling 10 tonne/hectare (140 bushel/acre)
cereal crops for example. They have even been known to pass
unblocked along the bunched (un-spread) windrow left by a combine
when harvesting such a crop.
55. What is meant by micro-management of residues?
Most people know that residues spread over a field are one of the
main attributes of no-tillage in general. This is macro-management
of the residues. But most competing openers either push the residue
aside at the slot zone or push a portion of it down into the slot
where it contacts the seed, simply as a by-product of trying to
handle it without blocking.
Cross Slot openers do neither. They raise it up with the soil flap
and then replace it back where it came from after the seed is
deposited, as a means of trapping soil humidity. Cross Slot openers
use residues as an important tool in their superior biological
functioning. This is micro-management of the residues. Other openers
treat residues as an impediment to their functions. That is a key
difference between Cross Slot openers and competing designs.
Operators must choose how much value they place on residues when
choosing a no-tillage opener.
ENGINEERING DESIGN
56. It is one thing to have good biological design but what about
engineering design?
Cross Slot openers and machines have a 10,000-hour design life,
which is similar to tractors? The designers of Cross Slot figured
that if a farmer ends up owning only a tractor, sprayer and Cross
Slot drill (as many already do) it makes sense for the drill to last
as long as the tractor and the sprayer, both of which are likely to
be designed with a 10,000-hour life.
57. But doesn't every manufacturer claim their machines are "robust
and long-lasting"?
Unfortunately yes! But at the 1998 US National No-Tillage Conference
it became clear that this was simply not the case in practice with
most no-tillage drills and planters. No-tillage machines have much
larger stresses applied to them than conventional drills and
planters because the soil has not been pre-loosened. Even machines
from reputable manufacturers are lasting less than three years (and
some less than that) because they have been designed more as
enlarged versions of conventional machines than as specialist
no-tillage machines. The shortest time we have known a rival
no-tillage drill to wear out in was three months.
58. What wears out on no-tillage machines?
Just about everything, but especially pivoting joints. Of course the
soil-engaging components (discs, blades and scrapers) are expected
to wear out anyway, but when the above-ground components become
loose, openers become misaligned, row spacing suffers, residue
handling suffers, seed placement suffers, different openers on the
same machine behave differently, and downforce application becomes
inconsistent.
59. How are Cross Slot machines different in relation to wear?
All major pivoting joints use pre-packed ball or roller bearings
similar to how tractors (and cars) are constructed. Special
triple-lipped seals are employed that ensure bearings continue to
stay clean even in the dustiest conditions. There are only three
grease points per opener that require regular attention. All other
pivots (including disc and press wheel axles) only require checking
once per season.
60. But the work done in one season for one operator might be very
different from the work done by another operator?
True. Operators in New Zealand probably demand more from their
equipment than operators in most other countries. Because much of
the drilling (and some of the planting) in New Zealand is done on
hillsides and there are fences surrounding all fields with
relatively narrow (11-14 foot wide) gateways. Most New Zealand
no-tillage drills and planters are therefore relatively narrow. Such
narrow machines have to go around any given field more times than a
wider machine to cover the same area.
On average, each Cross Slot drill in New Zealand covers about 1,000
hectares (2,400 acres) per year. This is equivalent to covering up
to four times that area in more expansive agricultural systems and
fields. A small drill in New Zealand covering 1,000 hectares/year
will travel about 3,000 kilometres in drilling mode and some have
been known to travel up to 8,000 kilometres in a year. Several Cross
Slot drills are known to have covered up to 20,000 hectares (50,000
acres) in 10 years in New Zealand in soils ranging from abrasive
volcanic soils through silts, clays, sands and rocks. And all of
them are still going strongly.
We think that New Zealand is a fair test for any machine.
61. What about wear on the soil-engaging components of Cross Slot
openers?
Currently Cross Slot openers use a nickel-chromium alloy that is
used by many manufacturers to cast the non-rotating soil engaging
components. But we are also working with a government-research group
to develop new ceramic materials that promise to extend the useful
life of blades still further.
Surveys conducted on the New Zealand machines over 5 years show that
the average cost for soil-engaging component wear is about NZ$7-10
per hectare (equivalent to US$2 - 3 per acre). In high clay content
soils this cost may be halved and in abrasive soils it may be
doubled.
62. What is the minimum row spacing of Cross Slot openers?
We know of one machine operating at 140 mm (5.5 inch) row spacing,
but 150 mm (6 inches) is more common. Of course there is no upper
limit to row spacing.
63. How does this compare with other machines?
There are several other no-tillage openers capable of operating at
150 mm spacing but none that apply fertilizer simultaneously with
the seed. Most others that apply fertilizer have minimum row spacing
of 180 mm (7 inches) or wider because of the complexity of their
designs, which consist mainly of two openers, joined together.
POWER REQUIREMENT
64. What tractor power is required to operate Cross Slot machines?
This is a commonly asked question. On flat-to gently rolling ground
Cross Slot openers require about 8 -10 engine horsepower per opener.
On softer soils, 7 - 8 hp per opener is sufficient and on steep
hillsides 12 - 15 hp per opener may be needed.
65. This seems a lot compared with the 5 hp per opener often quoted
by other manufacturers.
It is certainly more than for most other openers. It is the price
operators pay to get superior biological results, especially the
certainty of reliable crop stands and likelihood of superior crop
yields. If an operator sees no-tillage only as a cheap option, then
that operator will never achieve crop yields approaching what is
possible with tillage or Cross Slot no-tillage.
The fact is that the process of tillage makes drilling the seed a
relatively easy and cheap procedure. When tillage is eliminated, no
tillage then becomes a very demanding operation. Nonetheless the
total energy you put into sowing each hectare is much less under
no-tillage (by about 75%) than under tillage. The problem is that it
is all applied in one pass, compared with several passes with
tillage. This means one large tractor has to be used with
no-tillage. And no-one has yet found a way of achieving consistent
success with no-tillage without using a sophisticated drill.
Some would say that no-tillage is a short cut. When operators
attempt to shortcut the short cut, biological performance will
almost certainly be the victim.
66. But isn't this just sales talk?
The only way to see the value of Cross Slot machines in their true
perspective is to talk with current owners. A survey of New Zealand
owners was carried out in 2001. It covered some 40,000 hectares
(100,000 acres) drilled with Cross Slot machines over a period of 4
years (8 seasons) in some 6,000 separate fields, sowing a very wide
range of crop and pasture species into an equally wide range of soil
and residue conditions. Operators were asked to rank the percentage
of their crops that turned out equal to or above the district
average yields, and those that were below district average yields.
In the latter case they were also asked to identify the causes of
impaired crops. There was no gain for operators answering in any way
but honestly.
90% of crops had been at or above district average yields.
Some crops topped national yields and many topped district yields.
9% of crops had been below district average yields due to poor
management (inadequate weed or pest control, too early planting,
driver error etc - i.e. non-drill problems).
1% of impaired crops were identified as machine problems, and one of
those problems (tire tracks of drills causing seedling emergence
problems) has already been eliminated.
In other words the Cross Slot machines proved to be 99% failsafe!
We are not aware of any comparable surveys of other no-tillage
machines anywhere in the world, nor of the failsafeness of tillage
itself, but we doubt if any would come up to this standard. Who, for
example would claim that tillage has ever been 99% failsafe over the
years?
67. Are you saying that in no-tillage big and expensive is always
better than small and cheaper?
No! There are examples of big and expensive no-tillage machines that
turned out to have added very little to the failsafeness of
no-tillage. And some smaller cheaper machines that achieved success
in specific conditions. But it is hard to find operators of small
cheap machines who are confident of achieving success all of the
time with no-tillage machines.
We are saying that sophistication (not to be confused with size or
complication) is always cost-effective.
68. Please explain the difference between sophistication and
complication.
There are well-known no-tillage openers that require up to 14
adjustments per opener to cope with different soil and residue
conditions. Such openers require a high level of operator skill to
be successful. There are also well-known no-tillage openers for
which operators can buy some 13 different after-market attachments
designed to improve their performance. These are examples of
complication. Just read some of the questions on the Internet chat
session sponsored by No-Tillage Farmer magazine (USA) for evidence
of the knowledge and skills being exchanged between operators in
this regard as they constantly seek to improve the performance of
their machines.
Cross Slot no-tillage openers have only three adjustments, and one
of these is made from the tractor cab and is automated anyway. The
only adjustment usually needed when going from one soil condition to
another is the downforce applied to the openers. No opener
modifications are ever necessary to cope with different types or
levels of surface residue, wet or dry. Seeding depth may have to be
adjusted when going from one crop to another, but fertilizer and
seed separation occurs regardless of soil or surface conditions or
forward speed.
This is sophistication.
69. Is there an argument regarding no-tillage machines for adopting
the "horses for courses" approach?
Some people have argued that way. But most farms contain several
different soil types, especially with the trend towards amalgamation
of farms these days. And in some cases these soil types may change
their characteristics with moisture content. Some may even change
with overnight rain. It is non-sensical therefore to expect a farmer
to have several different no-tillage drills on hand to cope with the
different conditions as they occur. In any case this would increase
the capital expenditure and negate the purpose of buying a cheap
drill in the first place.
It is better to invest in a single sophisticated machine that will
handle all conditions, such as Cross Slot.
70. Can an operator really rely on a Cross Slot machine to be truly
universal?
There are very few (if any) conditions that Cross Slot machines
cannot cope with. That is partly why it has taken so long to
develop. The designers and scientists needed to know that a farmer
could truly rely on no-tillage full time with such a machine, which
would ultimately give that operator the confidence to literally sell
the plough and rely 100% on no-tillage.
Several operators in New Zealand and the USA have done exactly that
and never looked back.
71. Why are Cross Slot openers harder to pull than other openers?
For two reasons:
Firstly, they do a lot more work on loosening the soil in the root
zone than other openers. Most other openers, at best loosen the soil
at the surface where it is not required or simply do not loosen the
soil at all. Some in fact compact the soil rather than loosen it.
Secondly, the way in which Cross Slot openers are designed to handle
surface residues (by rubbing two blades on the side of the central
disc) produces a disc-braking effect that creates drag. But since
this function is fundamental to the superior operation of these
openers it is simply one of the costs that must be paid to get
superior crops.
72. Are Cross Slot openers any harder to push into the soil than
other openers?
It is easy to get that impression because Cross Slot openers are
capable of applying downforces up to twice those of their
competitors. But measurements have shown that a single Cross Slot
opener requires about the same downforce to attain a given seeding
depth as an equivalent diameter double disc opener. The difference
is that Cross Slot openers will promote seedling emergence from
soils that are far too dry to even contemplate sowing into with
double disc and most other openers. Therefore Cross Slot openers get
used in drier ground than other openers and thus require higher
downforces to cope with this.
73. What is the range of downforces that Cross Slot openers can
achieve?
0 to 500 kg (1,000 lbs) per opener.
74. Doesn't it require a very heavy drill to achieve 500kg downforce?
Yes but that amount of downforce is only required when the soil is
very dry and hard. So Cross Slot drills are designed so that weight
can be easily added and removed. They have a basic weight of 300 kg
per opener and this can be increased to 500 kg per opener when
needed by adding ballast weights in 0.5 tonne increments with a
front end loader or even the drill's own optional on-board crane .
The ballast weights are in the form of suitcase weights that are
hung on (or removed from) the side of the drill when required.
75. Can Cross Slot openers be attached to other no-tillage machines?
We do not know of any current drill frames (anywhere in the world)
that are capable of having Cross Slot openers fitted to them. With
planters nearly all brands are capable of receiving Cross Slot
openers, albeit that a special bracket is supplied to place the
openers directly under the seed dispensing mechanisms of each make
and model of planter.
Most wide toolbars are capable of receiving Cross Slot openers,
albeit that some strengthening may be necessary for the forces
involved and to carry the ballast required. The air seeder units
used with tool bars must be capable of delivering seed and
fertilizer to the openers in separate tubes or some of the important
benefits of Cross Slot openers will be lost. Otherwise Cross Slot
openers are compatible with all known air seeders.
ECONOMICS
76. Is it really economic to invest in a sophisticated (and no-doubt
more expensive) no-tillage machine compared with cheaper
alternatives?
Only if the more sophisticated machine gives you a better crop.
Operators must put a value on two things:
1. The cost of crop failure, or alternatively the cost of having to
re-drill or re-plant a crop.
2. The returns from say a 1%, 5%, 10%, 15% and 20% gain in crop
yield.
77. Can you give examples?
Take, for example a spring milling wheat crop in New Zealand sown by
two no-tillage contractors (custom drillers) with two different
machines. One contractor (with a cheaper machine) charges US$60 per
hectare (US$20/ac) for drilling. The other contractor with a Cross
Slot machine charges US$105 per hectare (US$47/ac).
Typically, the cheaper no-tillage machine will produce a crop yield
that is somewhat below average, say 5.5 tonne per hectare at
US$130/tonne. Gross returns from the cheaper machine will therefore
be US$715 per hectare. "Net" returns (with drilling costs only
deducted), will be US$655 per hectare.
The additional cost of drilling with the more sophisticated machine
is US$45 per hectare or US$27/ac (US$105/ha vs US$60/ha). In order
to recover the additional drilling cost, the more sophisticated
machine would need to increase the gross returns by at least US$45
per hectare, which is equivalent to increasing the crop yield by
0.35 tonne per hectare or 6%.
Trials by the US Department of Agriculture indicated that a 13%
increase in the yield of spring wheat was achievable using a Cross
Slot drill in Washington State. Applying those data to New Zealand,
such an increase would result in a "net" return (drilling costs only
deducted from the gross crop returns) of US$703, which is US$48 per
hectare higher than the "net" return of US$655 obtained with the
cheaper machine. A farmer growing 100 hectares of spring wheat would
therefore be US$4,800 better off.
It is therefore difficult to make a credible argument in favour of
cheap no-tillage machines that fail to achieve the full yield
potential of crops sown by no-tillage.
OPERATION
78. What is the maximum speed that Cross Slot machines can drill at?
Cross Slot openers will operate quite satisfactorily at up to 16
km/hr (10 mph). Such a speed is usually not comfortable for the
operator so a lot of drilling is done at 12-14 km/hr. With planters,
speed is usually limited by the maximum allowable speed of the
seeders, which is usually in the 8-10 km/hr range.
79. What are the advantages of going fast anyway?
A wide machine going slowly might drill or plant at the same rate as
a smaller machine going fast. But the smaller machine will cost less
even although both might use the same sized tractor.
On the other hand some no-tillage openers use angled discs that
displace soil to one side. Speed has a profound effect on how they
operate because the sideways-displacement action is very
speed-dependent and generally limits how fast they can be driven.
80. Can Cross Slot machines be used on steep hillsides?
The only limit to how steep a hill a Cross Slot drill can be
operated on is the stability of the tractor and ability of the
tractor to pull the heavy machine up and down hills. Generally it is
better to pull Cross Slot drills across hillsides because they are
heavy and require a lot of traction to pull them straight up a hill,
for example.
We have met operators who use their Cross Slot drills on 52% (47
degree) slopes in the USA.
81. Is there any difference between how well Cross Slot openers work
on gravity or air drills?
No! Cross Slot openers work just as well with both methods of seed
dispensing.
82. Is there a preferred method of seed dispensing?
In New Zealand, most Cross Slot drills operate with air seeders
mounted on the drill frame (air drills). This design allows an
operator to expand the size of the drill at a later date by fitting
additional openers without having to change the entire drill. Air
drills deliver the seed in an air-flow down flexible plastic tubes
that do not need to be directly under each seeder in the same way
that gravity seeders need to be. Therefore adding extra openers can
be accommodated easily by directing extra seed tubes to wherever
they are required.
83. What machines are Cross Slot openers available on?
Currently the following machines are available:
" Rigid-frame end-wheel air drills from 1.8 m (6') to 3.5 m (11' 6")
sowing width.
" Folding end-wheel air drills from 4 m (13') to 6 m (20') sowing
width and 3 m (10') transport width.
" Wide line folding toolbar air seeders (using trail-behind air
carts) from 9 m (30') to 18 m (60') sowing width and fore and aft
wheels.
" Retrofit kits for attaching Cross Slot openers to existing
toolbars.
" Precision planters for wide row crops.
" Single-row drills for animal power or small tractors.
84. Where can I get further information about Cross Slot openers and
machines?
The web site is www.cross-slot.com
FAO (of The United Nations) has commissioned the inventors of Cross
Slot no-tillage systems and machines to write a book explaining the
science behind the answers given above in layperson's terms. The
book, entitled No-Tillage Seeding in Conservation Agriculture
(Baker, Saxton, Ritchie, Chamen, Reicosky, Ribeiro, Justice and
Hobbs) is due for release early in 2006 (CABI, Oxford, UK) and is a
sequel to No-Tillage Seeding: Science and Practice (Baker, Saxton
and Ritchie).
It will be available from FAO, Rome, Italy and Baker No-Tillage Ltd,
P.O. Box 181, Feilding 5600, New Zealand.
The management steps needed to undertake successful no-tillage as a
practice, are described in the book Successful No-tillage in Crop
and Pasture Establishment (Ritchie, Baker and Hamilton-Manns) which
is available from Baker No-Tillage Ltd, P.O. Box 181, Feilding 5600,
New Zealand).
The inventors and controllers of Cross Slot technologies can be
contacted at (baker.bnt@inspire.net.nz) or (ritchie.bnt@inspire.net.nz)
or (bnt@inspire.net.nz). |
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