Top Crop Manager

Features Agronomy Harvesting
It’s never too early to think about harvest

Weather conditions made harvest difficult for many growers in 2006


November 13, 2007
By Top Crop Manager

Topics

48aWeather conditions made harvest difficult for many growers in 2006. Even though
weather is unpredictable, there are season-long management considerations, starting
with seed selection, which can help keep harvest from turning sour.

Hybrid selection is a major consideration that can impact harvest, but that
is just the first on a list of influencing factors that also includes soil type,
disease or insect prevalence, farm type and livestock needs. When considering
harvesting ease, hybrid selection for maturity, drydown and standability are
key. Dave Townsend, CCA, technical services manager, NK Brand, Syngenta Seeds,
and Greg Stewart, corn specialist, Ontario Ministry of Agriculture, Food and
Rural Affairs, offer growers three different philosophies, with various levels
of risk, for selecting hybrids.

Hybrid selection guidelines can help spread risk and
maximize yield

Townsend recommends spreading risk by using the traditional 20:60:20 maturity
rule. Planting 20 percent long-season hybrids as soon as possible in the spring,
followed by 60 percent full-season hybrids and finally 20 percent short-season
hybrids. This rule can stand alone or can incorporate a second philosophy.

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"Within the 20:60:20 approach, growers may also consider selecting 60
percent elite hybrids and 40 percent defensive hybrids," explains Townsend.
"Elite hybrids typically offer less disease tolerance and may sacrifice
the stalks to maximize yield. Defensive hybrids, on the other hand, offer a
stronger agronomic and disease package, which can improve harvesting ease in
years like 2006, but may result in lower yields."

Application of these rules depends on how risk-averse growers are and also
on their farm needs. Livestock producers growing silage corn, for example, may
want to consider selecting hybrids on an 80:20 basis for maturity. "Because
livestock producers require consistent high quality for silage, an 80:20 split
would allow for selection of hybrids that enable producers to fill the silo
or bunk over a quick harvest window, with some flexibility to top up at the
end of harvest," says Townsend.

Stewart approaches hybrid selection from a different angle. "Compared
to the 20:60:20 rule for maturity, I suggest considering a 50:50:0 split, as
long as you can plant on time," says Stewart. This rule aims to maximize
yield potential by planting 50 percent long-season hybrids and 50 percent full-season
hybrids.

"Generally, yield will be there to compensate for higher moisture,"
adds Stewart. "But success using this method depends on early planting.
If you can't plant early or on time, consider switching to soybeans before selecting
a shorter season corn hybrid that won't maximize the region's yield potential."
When making hybrid choices, Stewart also reminds growers to maintain perspective
regarding 2005 and 2006 record yields, which were the product of above average
heat unit accumulation.

Stewart notes that his 50:50:0 rule originated during the winter of 2006 when
growers faced record low corn prices. But with stronger corn prices going into
the 2007 season, he says there should be some opportunities to make a profit
on corn planted beyond the optimal seeding date.

Early scouting helps avoid harvest challenges
To help ensure a successful harvest, Townsend recommends growers plan ahead,
starting with late summer and early fall scouting for stalk strength, standability,
corn borer damage and disease. "The sooner growers can harvest poor fields,
the higher the yield and quality," says Townsend.

Silage corn growers should begin scouting in late August, while grain growers
need to be walking fields after Labour Day. Growers should check for corn borer
damage on the cob and stalk as well as the shank: between the cob and stalk.
A simple pinch test (pinching the stalk two nodes from the ground) is an effective
method to determine stalk strength and help gauge how long the corn will stand
or can be left before harvesting.

It is also important to assess root strength as wet soil from excessive rain
can increase risk of late-season root lodging. Townsend also reminds silageproducers
to check their moisture using a microwave, rather than relying only on milk
layer progression. "New leafy silage hybrids tend to hang onto moisture
longer in the stalk and leaves, and have too much moisture even when milk line
indicates it's ready for harvest," says Townsend.

Data suggest economic gain from maximum yield trumps
drying cost

When it comes time to harvest, growers often face tough decisions. Do they harvest
to reduce risk of lodging, yield and quality loss, but incur higher drying costs,
or leave the crop standing to avoid drying cost and risk sacrificing yield and
quality? Ultimately, considerations impacting this decision are different for
each grower, says Townsend, but yield and quality should not be sacrificed to
cut drying costs. "Once stalks lodge and ears are on the ground, harvest
loss increases substantially. It doesn't take many ears on the ground to pay
a little extra for drying," adds Townsend.

This is where Stewart's 50:50:0 rule falls back into place. "If growers
can plant early and maximize yield, yield will trump drying costs," says
Stewart, who has tested this approach by analyzing data from the Ontario Corn
Committee (OCC) hybrid performance trials. He first assessed the yield gain
growers could expect if they moved to a longer season hybrid with higher harvest
moisture. He then considered whether this potential yield gain was enough to
compensate for additional drying costs. "After analyzing 2004 trial data,
I found on average four bushels per acre yield is gained for every point that
harvest moisture increases," explains Stewart. "And given corn prices
and commercial drying costs at that time, the yield gain did outweigh drying
cost."

Stewart is seeing the same trend emerging in 2006 OCC trials, especially in
the 2850CHU to 3000CHU maturity (see chart), which includes Exeter, Woodstock,
Ilderton and Thorndale. Here the data indicate a nine bushel per acre yield
gain for every point that harvest moisture increases.

Stewart reminds growers, however, that this is not always the case. Be careful
with hybrid selection as some hybrids may provide little extra yield for higher
moisture, meaning yield would not trump drying costs. It is also dependent on
being able to plant early to maximize yield potential.

Step-by-step microwave testing
Follow these tips on how to use a microwave to accurately test plant moisture.

  • Begin with a field-chopped sample of the crop.
  • Weigh and record weight of empty paper plate or bag (A).
  • Spread out 80 to 125 gram sample evenly on plate or in bag (B).
  • Weigh and record weight of B. Don't forget to put a glass of water
    in the microwave…
  • Dry sample on 'high' for two minutes.
  • Remove, record weight and gently stir sample.
  • Continue for intervals of 30 seconds to one minute on medium to low
    setting until sample weight stabilizes – remains the same for three
    drying intervals – (C).

If sample becomes charred start over again.

To calculate moisture, follow this formula:

[(B-A) – (C-A)] divided by (B-A) x 100 = percent
moisture.
Source: OMAFRA.

 

 


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