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Maine Grain and Oilseed Newsletter - Vol. 1, No. 4 — August 2013

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field of ripe grain

Maine Grain and Oilseed Newsletter

Vol. 1, No. 4 — August 2013

57 Houlton Road, Presque Isle, ME 04769
207.764.3361 or 1.800.287.1462
extension.umaine.edu/aroostook

Dear Grower,

Harvest season is upon us. It has been a difficult growing season for some grains and not too bad for others. Looking at some fields around, it appears to have been a fair to moderate season for most in terms of grain quality and quantity. This month’s newsletter will hopefully provide you some use as you commence your grain harvest activities. We are happy to announce our new Maine Grains and Oilseeds website. On the website, you will be able to find copies of the newsletter, factsheets, videos, and links to additional information.

Good luck with your harvest.

Sincerely,

Andrew Plant, Extension Agriculture Educator

Ellen Mallory, Sustainable Agriculture Specialist


Harvesting Wheat and the Falling Number Test

Ellen Mallory, University of Maine Extension Sustainable Agriculture Specialist

Producing high quality bread wheat requires special attention at key crop stages, including harvest. Wet, humid weather and delayed harvesting can favor preharvest sprouting, during which alpha-amylase enzymes are released in the kernel and begin converting starches to sugars. This has a detrimental effect on end-use quality, causing sticky dough and reducing dough strength. 

Millers and bakers use the Falling Number test to measure the degree of sprout damage in the grain. The falling number test mea­sures how quickly a plunger falls a certain distance in a slurry of flour and water. As enzyme activity in­creases and the conversion of starches to sugars progresses, the viscosity of the slurry and the falling number values decrease. Low falling numbers can indicate that pre-harvest sprout damage has occurred.  Generally, 250 seconds is the minimum acceptable falling number level, but this can vary from mill to mill. As little as 5% heavily sprouted wheat in a mill mix of otherwise sound grain can make the resulting flour unacceptable for bread production.

At this point in the season, harvesting in a timely manner is the most important management factor for minimizing preharvest sprouting and assuring an adequate Falling Number. Be ready for harvest well ahead of time, and begin harvesting once the grain reaches 18% moisture. Harvesting at a higher moisture content requires being prepared to dry the grain down to 13 or14% moisture before storing, but reduces the risk of a rain event delaying harvest and damaging the crop. Timely harvest is also important for minimizing DON levels and weed growth.

There is currently no simple test kit for the Falling Number, so samples must be submitted to a grain quality testing laboratory, such as the following:

University of Vermont Cereal Grain Quality Laboratory
James M Jeffords Building, 63 Carrigan Dr., Burlington, VT 05405; (802) 524-6501;  www.uvm.edu/extension/cropsoil/grains

Great Plains Analytical Laboratory (formerly CII)
9503 N. Congress Avenue, Kansas City, MO 64153; (816) 891-7337;  www.ciilab.com

For more information about the Falling Number test and other wheat quality tests, see the following publications:

  • Understanding Wheat Quality: What Bakers and Millers Need and What Farmers Can Do. UMaine Extension Bulletin #1019, available at http://umaine.edu/publications/1019e/
  • Wheat and Flour Testing Methods: A Guide to Understanding Wheat and Flour Quality. The Wheat Marketing Center and Kansas State University, available at http://www.wheatflourbook.org/.

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Harvest Efficiency and Combine Adjustment

Andrew Plant, Ag Educator, UMaine Extension

At the beginning of the season we discussed seeding rates and grain drill calibration. Now, at the other end of the season, combine setting and adjustment is equally important to putting a high quality, cost-efficient crop into storage. Modern combines do a great job with threshing and cleaning grains. Invariably though, a portion of the crop will still be left in the field or damaged due to crop conditions or improper combine adjustment. Our goal is to minimize this loss. Beyond the initial settings provided in your combine manual, there are several things you can do to assess your combine operation and make corrections if needed:

Combine efficiency during grain harvest is assessed by estimating loss behind the header and behind the separator. In order to determine a percentage of loss we need to estimate harvested yield, lost yield behind the separator, lost yield behind the header, and pre-harvest loss (loss not due to the actions of the combine). 

Figure 1. Assessing Grain Harvest Efficiency.

combine efficiency diagram showing standing grain in front of the combine (estimate pre-harvest loss here, arrow showing 20 ft in the direct front of the combine, arrow showing edge of standing grain (of the 20 ft span) an arrow pointing out where you will estimate header loss(in the 20 ft in front of the combine) an arrow pointing to the header (front of the combine), the area around the combine is the harvested grain, an area pointing to the residue spreader and the area behind the combined area where you will find the estimate total loss

Harvested Yield Estimate

To estimate harvested yield (bu/ac), you can do so by judging the amount of crop going into the combine after starting to harvest.  Most combines are equipped with an acre counter and one can judge by the number of acres to fill a known volume with grain.

To determine harvest efficiency and loss, cut up to a certain point in a representative portion of the field so that there is still standing grain.  Back up 20 ft (or at most the length of the combine) from that point and do counts behind the residue spreader first, and if needed, between the header and standing grain, and in the standing grain (Figure 1).

Table 1. Square foot seed count estimates for 1 bushel harvest loss of selected small grains and oilseeds.  The numbers below represent typical grain seed counts per square foot for different grains that would represent 1 bu/ac, depending on the location you are doing counts.  When conducting counts for total harvest loss, use the number that corresponds to the type of residue spreader you use. 

Seed Count per square foot = 1 bu/ac
      Total Harvest Loss (Residue Spreader Type)
  Pre-harvest Loss Header Loss Windrow Batwing Chopper Chop + Spread
Wheat 20 20 80 65 50 25
Barley 15 15 60 49 38 19
Oats 11 11 44 36 28 14
Soybean 4 4 16 13 10 5
Canola* 1g 1g 4g 3.25g 2.5g 1.25g
*by weight using a 1 sq. ft. catch pan, equates to approx. 100 lbs/ac  

Total Harvest Loss

Check for total harvest losses in back of the combine first (behind residue spreader).  This will save time; if seed counts (the number of grain kernels either loose or in heads on the ground) behind the combine are below one’s threshold for harvest loss, there is no need to do counts elsewhere.  Counts should be taken from 3 different spots behind the separator, 1 ft2 each, and averaged together.  A handy tool to have is a square foot frame built out of some spare lumber or lathes.

Total harvest losses shouldn’t exceed 1%-2% of total yield. To estimate the percentage loss:

% Total Harvest Loss = 100 x  ((Ave. Seed Count/ft2 behind spreader) / (Seed Count in Table 1))
Harvested Yield Estimate

If the total percentage loss behind the combine separator is above one’s threshold, you should now do counts to determine header loss and pre-harvest loss to see where the actual grain loss is coming from.

Pre-Harvest Loss

Take seed counts like you did behind the residue spreader, but do so now in the standing (uncut) portion of the field. 

% Pre-harvest Loss = 100 x  ((Ave. Seed Count/ft2 in uncut portion) / (Seed Count in Table 1))
Harvested Yield Estimate

Header Loss

Between the header of the parked combine and the standing grain, repeat the counting procedure by taking 3, one square foot counts of seed. 

% Header Loss = 100 x  ((Ave. Seed Count/ft2) / (Seed Count in Table 1)) – % Pre-harvest Lost
Harvested Yield Estimate

Header losses shouldn’t exceed 0.5%.  If losses are exceeding, see below for combine adjustment tips and consult your manual. 

Separator Loss

At this point you’ve completed all of the counts that you need to take, but you need to determine the percentage loss occurring due to the separator.

% Separator Loss = % Total Loss – % Pre-harvest Loss – % Header Loss

Separator Loss shouldn’t exceed a range of 0.5% to 1.5%, depending on the comfort level of the farmer. If losses are exceeding, see below for combine adjustment tips and consult your manual. 

Once losses are determined, corrections can be made on a systematic basis depending on where the losses are coming from, and observations of the condition of grain kernels and straw:

Key to Combine Adjustment:

1.  Is header loss greater than 0.5%? If NO, go to #2. If YES, What type of loss?

a.)  Shattered Kernels? Check reel speed (too fast), Check ground speed (too fast), Poor knife condition (sharpen knives) 
b.)  Whole Heads? Check cutterbar height (too high), Check reel speed (too slow), Check reel height (maybe too high or low).

2.  Is separator loss greater than 0.5%-1.5%? If YES go to #3. If NO, keep harvesting.

3.  Are engine and separator speeds “OK” (according to manual)? If YES, go to #4. If NO, adjust speeds.

4.  Is ground speed too fast? If NO, go to #5. If YES, slow down.

5.  What type of loss are you observing?

a.) Unthreshed kernels? Increase cylinder speed or decrease clearance.
b.) Loose kernels? Go to #6.

6.  Are you observing pulverized straw or cracked grain? If YES, reduce cylinder speed or increase clearance. If NO, go to #7.

7.  Check the chaffer opening. Is it too narrow? If YES, adjust. If NO, go to #8.

8.  Check the fan setting.

a.) Too strong? Kernels will blow out the back, and will be observed to drop off the chaffer. Adjust fan speed down.
b.) Too weak? Observe chaffer filling up with chaff, grain will ride out back on top of chaff, unable to fall through to sieve. Adjust fan speed up. 
c.) Fan speed OK? Go to #9.

 9.  Chaffer extension OK? Adjust if needed.

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© 2013
Published and distributed in furtherance of Cooperative Extension work, Acts of Congress of May 8 and June 30, 1914, by the University of Maine and the U.S. Department of Agriculture cooperating. Cooperative Extension and other agencies of the USDA provide equal opportunities in programs and employment.

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