Is it time to consider applying ammonia at seeding?
By John Harapiak
If you failed to get your NH3 on last fall, consider this spring option.
The 2004 prairie crops were significantly delayed by cool weather. Unfortunately,
harvesting weather was equally as discouraging. Rain and snow created very poor
conditions for getting fall work completed. For many growers, one of the key
tasks that did not get done was the fall application of ammonia.
Many growers prefer NH3
There are many prairie growers who are dedicated users of anhydrous ammonia.
The high N concentration, the ease of handling, in-field dealer servicing and
a lower unit cost of N are some of the reasons for the continuing popularity
of this N fertilizer. In fact, anhydrous ammonia usually accounts for about
one-third of the market for nitrogen-based fertilizers. Normally, 30 to 40 percent
of the NH3 is applied in the fall. For some growers,
especially those farming heavy-textured soils, fall is the only time they will
consider applying NH3, although options for spring application
Fall often preferred time for NH3
For a significant percentage of the growers who apply ammonia, fall is the preferred
time for application. They find that getting this task completed in the fall
allows them to streamline and to significantly speed-up their seeding operations.
For these growers, applying NH3 in the spring could conceivably
double the amount of fieldwork and would result in delayed seeding. For growers
farming clay soils, application of NH3 in the spring
prior to seeding is not an option because of the adverse impact on seedbed quality
of putting a heavy NH3 application in the field prior
Applying NH3 at seeding
For about 10 years, an increasing number of growers have adopted the concept
of applying NH3 at the time of seeding. This approach
to ammonia application was first 'championed' by Westco research agronomists.
While the concept was initially treated with a great deal of skepticism, grower
experiences have shown that with proper care and caution, applying ammonia at
seeding can be a very effective practice.
Results from field trials
A significant amount of field research has been conducted within western Canada
comparing side-band applications of ammonia and urea at the time of seeding.
Some of this information is summarized in Table 1. The information suggests
there were no significant differences in the yields achieved with side-band
applications of either urea or ammonia at application rates ranging from 50
to 150 pounds per acre of actual nitrogen.
|Table 1. Summary of
trials comparing performance of urea and ammonia side-banded at the time
|Agencies involved||Study details||N rates used (lb/ac)||Crop||Average yield (bu/ac)|
|Agriculture and Agri-Food Canada, Westco, Conserva Pak||10 trials in Saskatchewan and Alberta||50, 75 and 100||Cereals||56.1||56.3|
Agriculture and Agri-Food Canada, Westco, Conserva Pak
||6 trials in Saskatchewan and Alberta||50, 75 and 100||Canol||20.5||20.5|
|Alberta Farm Machinery Research Centre||Evaluation of 14 openers||50, 75 and 100||Barley||91.6||92.1|
|Alberta Farm Machinery Research Centre||Evaluation of 14 openers||50, 75 and 100||Canol||25.3||25.1|
Achieving separation of NH3
and seed is critical
Unlike urea, ammonia can rapidly move away from the point of injection. That
means that greater care must be taken with NH3 in order
to ensure the expanded volume of soil containing the ammonia does not encroach
into the seedrow. If the ammonia contacts the seed, severe germination damage
is possible. For that reason, it is important the seedrow be separated from
the ammonia by an adequate barrier of soil.
Two distinct styles of openers have been successfully used for applying NH3
at seeding. The openers that use a cultivator shovel for placing the seed and
NH3 at the same level (eg. 'wing-tip' injectors), with
the injection point being at least one to two inches to the side of the seedrow.
The tumbling action of the soil as it flows over the shovel enables this approach
to be surprisingly effective in trapping NH3 in the soil.
Side-banding openers inject the NH3 one to two inches
to the side and one to 1.5in below the depth of seeding to achieve the required
Use NH3 detection kit to ensure
separation is adequate
Some of the suppliers of ammonia provide NH3 detection
kits that will enable you to measure the degree of separation achieved between
the ammonia zone and the seedrow. At least one inch of separation is required
to prevent germination damage. If the separation is less than one inch, adjustments
will be required. Worn openers and seeding at speeds exceeding 5mph increases
the risk of ammonia contacting the seedrow.
Do not attempt to place NH3
below the seedrow
Ammonia easily moves upward through a layer of fractured soil. For that reason,
attempting to place ammonia below the seedrow will result in the ammonia moving
upwards into the seedrow and destroying the seed. Also, attempting to side-band
ammonia too deep can also result in soil shattering that may allow ammonia to
move into the seed zone.
Beware of opener wear
There are many examples of new openers effectively maintaining a protective
barrier of soil between the seedrow and the ammoniated zone. However, after
they wear-out, those same openers will not adequately protect the seed from
ammonia damage. Therefore, when attempting to apply ammonia at the time of seeding,
ensure that the openers are performing as they should and replace any openers
that are worn.
Risk greater with NH3 than
The results included in Table 2 clearly illustrate the risk associated with
achieving inadequate separation between the seed and the N fertilizer is much
greater with ammonia than urea. In the case of urea, the loss in yield between
a new and a poorly performing, worn opener amounted to 1.9bu/ac of barley. However,
in the case of ammonia, the spread in yield between a new and a worn opener
was more than four times as great (i.e. 8.6bu/ac). As a rule of thumb, worn
openers used for seeding should always be replaced. In cases where ammonia is
being applied at seeding, replacement of worn openers is extremely critical.
Why growers like ammonia at seeding
Grower surveys indicate that finding ways of improving efficiency of field operations
is their number one priority. And, at no time of the year is this more important
than at the time of seeding. By placing a high-analysis source of N like ammonia
into a separate container, a great deal of additional space is made available
for seed and starter within the air-seeder tank. This results in significantly
fewer stops for refilling. Eliminating some of these stops can do a great deal
for improving efficiency of the seeding operation.
Is it time to reconsider your spring NH3
A significant number of growers are now dedicated to applying
their N requirements as ammonia at the time of seeding. This is no longer a
system under evaluation, but rather a proven and accepted practice. It is estimated
that 10 to 15 percent of the ammonia used in western Canada is now applied at
the time of seeding. Growers who use this single-pass seeding and fertilizing
system claim that their cost savings are substantial. If this is the year you
want try this approach, first take the time to learn about the associated risks
and benefits. Also be sure that you have a fertilizer retailer who will commit
to supporting you, so that your seeding operation is not shutdown waiting for
a needed delivery of ammonia. -30-
The Bottom Line
We have been applying ammonia at the time of seeding for four years now. The
development of openers that have a separation between fertilizer and seed have
made this possible. There has been a substantial saving by eliminating the separate
operation that was either done in the fall or spring time. Our air-cart and
ammonia tank are sized to do about the same number of acres, so when we are
filling with seed and dry fertilizer, the ammonia tank is being filled at the
same time, an efficient use of time. We are fortunate that with our Black loam
soils the one pass seeding system works well for us.
Jim and Peter Galloway, Fort Saskatchewan, Alberta.
Selecting level fields will be critical to the success of spring applied NH3.
The wet fall has left many fields badly rutted and uneven depth control could
be a big problem with NH3 applications next spring. If
depth varies a lot, N can be lost and seed safety compromised.
John Waterer, Winnipeg, Manitoba.
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