Getting to know your crop this summer
By Top Crop Manager
Scouting is an ideal way to assess sustainable crop production.
By Top Crop Manager
During the summer, crop scouting usually focusses on insects and diseases,
and while those are important pests to monitor, the summer crop scouting season
also offers the chance to assess crop health.
"Much can be learned, or at least problems can be confirmed, by observing
the growing crop in the summer," says Ron Heller, an agronomist with Alberta
Reduced Tillage Linkages (RTL) at Vermilion. "It's a chance to see if there
are areas in the system that can be improved upon. Often, those improvements
don't cost any money, but require just a change in practices."
|The most competitive variety with a higher seeding rate produced|
better crop health.
Heller cites the example of a farm call he recently made to troubleshoot a
seeder problem after a retrofit for direct seeding. The silage barley crop had
strips of green and mature plants running through the crop. The uneven maturity
was uniformly repeated across the field. Looking at the crop stand, missing
plants could be observed in some of the seedrows and digging in the furrows
revealed deeper seeding in some seedrows, which caused delayed and uneven emergence.
Counting the seedrows across the width of the machinery pass in the field and
comparing where the green rows were in relation to the air-seeder ranks indicated
the front shanks were seeding too deeply. That spring, the farmer had switched
from sweep openers/mounted harrows to narrow knife/gang-mounted packers, but
had seeded without on-going levelling in the field as conditions changed.
"My opinion was the change in draft and penetration between the wide shovel
to knock-on points combined with the running influence of the row packers was
different than the operator's previous experience," says Heller.
Heller explains that as the seedbed dried out in early June on this particular
field, the silage crop was seeded under more difficult conditions than his earlier
seeded fields, which had good seedbed moisture. As the grower seeded deeper
into moisture, the front of the machine likely sucked down under increased draft.
At the deeper depths, some soil may have also been thrown from adjacent rows
into the leading furrows, resulting in uneven packing of seed below different
depths of soil.
"It reminded me that a move from high disturbance seeding to low disturbance
is not just about changing openers, and that deep seeding is a very common error.
It takes practice and fine-tuning of things like speed and depth settings for
individual fields as the season progresses," explains Heller.
Assessing crop health
The stand establishment challenge that Heller described is an ideal example
of how farmers can use summer crop walks to assess crop health. Optimum crop
health is dependent on integrating all the possible economical and ecological
approaches available. Things like establishing a good plant stand with higher
seeding rates, optimum seeding depth and variety selection that promotes weed
competition. Higher seeding rates can produce plant populations that create
competitive crop stands, particularly if a poor competitive variety is grown.
Variety selection also becomes important as seeding date changes.
Optimum crop health, which can be assessed with spring and summer crop walks,
has been an on-going research topic at Agriculture and Agri-Food Canada's (AAFC)
Lacombe Research Station. Neil Harker, an AAFC research scientist, is working
on a long-term barley study (2001 to 2008) at Lacombe and Beaverlodge, Alberta,
as well as Brandon, Manitoba. The study shows the importance of crop health
in combating weed competition.
Harker's collaborators include George Clayton, Kelly Turkington, John O'Donovan,
Byron Irvine and Deb McLaren, all of whom contribute expertise from several
scientific disciplines. They have found that the best treatment for optimum
crop health includes a 'two time' barley seeding rate; a tall, competitive barley
variety and; rotational diversity whereas the poorest treatment includes a normal
barley seeding rate, less competitive varieties (short) and continuous barley.
After five years of study at Lacombe, the best practices led to excellent wild
oats management even when wild oats herbicides were applied at 25 percent of
label rate in all years. For example, doubling the seeding rate reduced wild
oats biomass by three times. Combining a tall competitive variety with the 'two
time' seeding rate reduced wild oats by eight times.
The poorest treatments had more wild oats even after wild oats herbicides were
applied at 100 percent rates in all years. Harker explains that crop canopy
and root health were more important for wild oats management than herbicide
rate. At the other locations, similar effects were noted in the best treatments
at 50 percent herbicide rates versus contrasting treatments at 100 percent herbicide
It should be noted that reduced herbicide rates were not incorporated into
the trials to see if farmers could cut rates. Rather, the reduced rates were
used as a mechanism to help illustrate crop competitiveness and crop health.
While crop health is an important component of weed control in any cropping
system, it is, perhaps, easier to obtain under reduced tillage systems. With
reduced tillage, weed seeds are left on the surface where they are subjected
to weathering, chemical degradation and desiccation, along with predation by
birds and insects. Microbial and fungal feeding also degrades weed seeds. In
drier areas, direct seeding also helps conserve seedbed moisture for better
germination and stand establishment.
Operational diversity can also increase crop health and reduce input costs.
For example, a normal date of silage harvest with low rates of herbicide can
enhance wild oats management, but early harvested silage is also a very effective
wild oats management tool in the absence of herbicides. Adding winter wheat
into a crop rotation can also improve diversity and crop health by moving seeding
and harvest dates around to keep weeds and insects off-balance. Direct seeding
has also improved winter wheat health by providing a better overwinter environment.
| Figure 1. Wild oats BM – maturity –|
1/4 x rate (2005).
Rick Taillieu, RTL agronomist at Camrose, Alberta, says that as August 1 approaches,
farmers should start to assess which fields could be harvested early enough
for winter wheat seeding. While some of that planning took place at seeding
with the planting of early maturing crops, Mother Nature can also change the
maturity dates, so planning for winter wheat becomes essential. Winter wheat
seed should be secured and the seeder tuned-up so that winter wheat can be sown
at the optimum date in late August/early September.
Harvest and fall considerations
During the summer, the success or failure of the last harvest's straw and chaff
spreading can also be evident. Uneven germination caused by poor seed-to-soil
contact due to mats of straw, or cold soils under heavy chaff, may show up as
uneven maturity as the crop nears harvest. If residue management has caused
problems in the past, consider fine-tuning the system. As every good direct
seeder says, 'residue management starts at the combine'.
The other side of the residue problem is too little. RTL agronomist, Don Wentz
at Lethbridge says that farmers who grow low residue crops like potatoes or
beans should start to plan the seeding of a fall cover crop. For late harvested,
low residue crop like sugar beets, which are harvested too late for a cover
crop, Wentz says erosion control practices like ridge tilling can help reduce
These are just some of the examples of how a summer crop walk can provide the
opportunity to assess crop health and provide insight into fine-tuning a direct
seeding system. And while you are at it, why not call a few neighbours and gain
the combined experience of some of the best experts in the field?