April/May 1997
Anticipating the Effects of Late Planting
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Prairie Grains is the
official publication of
the Minnesota
Association of
Wheat Growers,
North Dakota Grain
Growers Association,
South Dakota Wheat,
Inc., and the
Minnesota Barley
Growers Association.
By Michael D. Peel
NDSU small grains extension specialist
I can think of but one silver lining to the unusually heavy snowfall in the Northern Plains this past winter - adequate soil moisture early on shouldn't be a problem. The bigger picture points to a delay in spring planting for many. Late planting because you missed the opportunity is one thing, and you can expect a yield loss. However, late planting due to a delayed spring is something entirely different.
Timely planting is one of the most critical management practices any grower can do to ensure optimum yield. There is typically about a week to ten-day window of opportunity for maximum yields when planting spring wheat or barley. This window of opportunity starts when the soil temperature reaches 40° F and has dried enough to allow equipment on without causing undue compaction.
In North Dakota, this is generally the last half of April or first half of May, depending on the year and location. Delayed planting past May 15 typically results in a 0.5% per day reduction in yield. The main factor contributing to yield reduction is the increased probability for higher, potentially detrimental temperatures during the 4.0 to 5.5 leaf stage, when the number of spikelets on the head is determined.
However, if the whole season including favorable temperatures and rainfall is delayed, then yields may still be quite good. This was certainly observed by individual growers in 1996 who planted late and still had a fairly good yielding crop. This is not surprising, since daytime temperatures were largely in the range for optimum growth of small grains. The late-planted crop in 1996 may have avoided scab infections that hit earlier-planted wheat and barley, but don't use this as an excuse to delay planting; scab infections may just as well be late in 1997, depending on the weather conditions.
In reviewing old experiment station reports, I found examples of late planting due to a late spring, such as 1965 where yields were 2.4 bu/A above the ten-year average. On the other hand, years with a late spring such as 1974 have occurred where planting was delayed and yields were low.
Tips to insure the best yields
There are several things that can be done to insure the best yields if late planting does become a reality, and it is most likely. Late planting generally results in higher grain protein. While high protein is a plus in wheat, high protein barley may not make malt quality. If barley is in your crop plan, plant it first and make sure total nitrogen does not exceed your yield goal. Nitrogen recommendations for malting barley are 1.5 lbs/acre for every bushel expected yield, and 2.5 lbs/acre for every bushel of wheat.
As I already mentioned, high temperatures during early plant development, which tends to occur with late planting, will reduce tillering and kernel number and consequently yield potential. This can be offset in part by increasing seeding rates. A five to ten percent increase above typical seeding rates for every ten days planting is delayed beyond May 15 should be sufficient. And a prayer certainly won't hurt.