Cereals: Harvest and Storage


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Pub 811: Agronomy Guide> Cereal > Harvest and Storage

Order OMAFRA Publication 811: Agronomy Guide for Field Crops


Table of Contents


Optimizing Combine Adjustments

Operator manuals contain the best starting point for setting up a small grain harvest. Occasionally, conditions arise that require further adjustments. Harvest of fusarium-damaged grain, lodged crops or crops infected with dwarf or common bunt requires special attention. The easiest and best way to improve the grain sample in these situations is with proper combine adjustment. Often the difference between a marketable crop and sample grade wheat is in the combine set-up. Don't be afraid to experiment.

Storage of the crop allows the opportunity to upgrade the grain before delivery to an elevator or mill. This is particularly important for wheat infested with any of the bunt diseases. Many producers have experimented with re-cleaning the grain through screen cleaners, seed cleaners and fanning mills to upgrade the crop to a better sample. Elevator operators can also do this, for a fee. This can have tremendous economic benefit, where grain can be moved from salvage grade to milling grade. Upgrading the grain makes it much easier for the elevator to handle the crop and find a purchaser for the grain.

Fusarium-Damaged Grain

Combines use air blast to separate grain from the chaff in a normal harvest operation. Many of the Fusarium-infected kernels are small, shrunken and lighter than sound kernels. It is often possible to blow a large proportion of these Fusarium-damaged kernels out the back of the combine by increasing the air blast above normal ranges. In 1996, many producers operated combines at the maximum windblast to increase grade. Research conducted by Dr. Art Schaafsma (University of Guelph, Ridgetown College) in 1996 found a tenfold decrease in Fusarium-damaged kernels in the grain when fan speeds were operated at maximum blast (up to 300 rpm above book settings). Operating cleaning fans at these levels causes an additional loss of good kernels, up to 0.13 t/ha (2 bu/acre) Table 4-20, Effect of Different Fan-Speeds on Wheat Yield. This small yield reduction is insignificant if the crop can be made marketable, rather than being downgraded to feed, sample or salvage.

  Fan Speed (rpm)
Table 4-20. Effect of Different Fan-Speeds on Wheat Yield
  1,160 1,190 1,220 1,250 1,280 1,320 1,330 1,330
  Sieve Setting: 6 mm (1 1/4 in.) Front Closed
Good kernels on ground:
per m2 (per ft2)
125 (11.6) 340 (31.6) 263 (24.4) 379 (35.2) 446 (41.4) 470
t/ha (bu/acre)
0.06 (0.83) 0.04 (0.58) 0.11 (1.58) 0.08 (1.22) 0.12 (1.76) 0.14 (2.07) 0.15 (2.18) 0.14
Loss at 4.03 t (60 bu) yield: % 1.38 0.97 2.63 2.03 2.93 3.45 3.63 3.56

Source: Dr. Art Schaafsma, University of Guelph, Ridgetown College, 1996.
Case International 1644, Harus Wheat, Essex County, July 17,1996. Travel speed 6.8 km/h (4.2 mph). Rotor speed 880 rpm.

Harvest should not begin above 16% moisture if significant Fusarium is present. High moistures reduce the ability to blow out lighter Fusarium-damaged kernels.

Slowing the forward ground speed of the combine may further reduce Fusarium levels. This allows increased separation of the grain mass, giving the increased windblast time to separate the good kernels from the infected kernels. Consider adjusting the cleaning sieves (chaffer) to a more wide-open setting. This directs the air blast vertically, slowing rearward movement of the grain mass and aiding cleaning and separation. Use caution to keep heads and straw particles out of the grain sample if the chaffer is opened.

Unfortunately, there will be times that the grain cannot be raised to milling standards. If this occurs, consider storing as much of the damaged grain as possible. Often, as harvest finishes, the pressure eases on those involved in handling the crop. Marketers and millers are able to assess the markets that do exist and the best way to condition wheat to fit that market.

Remember that wheat going into storage must be dry (14% moisture or below). Damp wheat allows the Fusarium to continue to grow and produce toxins, further downgrading the crop. Check stored grain frequently to ensure that the grain stays in condition.

Lodged Grain Crops

There are several effective options for harvesting lodged grain crops.

Grain Lifters

Setting up a combine for lodged wheat takes extra time and care while in the field. Although flexible cutter bars on floating soybean heads are standard on combines today, consider using grain lifters, which lift the crop above the cutter bar. This is an inexpensive way of maximizing yields.

Knife Adjustment

On floating cutter bars, leave the knife tilted down and run the header in the float position as if harvesting a soybean crop. Take care not to feed rocks into the combine if choosing this option.

Reel Adjustment

Adjust the reel on the combine. Most reels are permanently on the best setting for soybean harvest (newer combines have hydraulic adjustment from the cab), but this setting is not appropriate for a lodged cereal crop. Set the reel forward and adjust the tine angle to be more aggressive, allowing the reel to physically lift the crop up off the ground and above the knife. Check the operator's manual for suggested settings and fine tune from there.

Harvesting Direction

The last option, an unfortunate reality in some years, is to harvest the grain in one direction so the lodged grain is tilted towards the header rather than away.

Bunt-Infected Wheat

To avoid being forced into harvesting a bunt-infected crop, use resistant varieties of properly treated seed. However, when bunt does infect the crop, harvest and storage must focus on minimizing bunt balls in the sample and reducing the "fishy" odour following harvest.

Do not harvest bunt-infected crops at high moisture. Spores from broken bunt balls adhere more easily to damp grain. Harvest dry grain using slow cylinder speeds and open concave clearance to minimize the number of bunt balls broken during the harvest process. Operate cleaning fans at high speed to blow as many of the bunt balls and bunt spores out the back of the combine as possible.

Storage of bunt-infected wheat is an effective way to upgrade the grain. Aeration is the key. Store bunt-infected grain in storage facilities with lots of aeration capability. Aerate the grain until the odour has disappeared. Take care when removing the grain from storage, as the handling process can break remaining intact bunt balls and re-contaminate the grain. Belt conveyors are preferable to augers when moving bunt-infected grain. Use of aspiration during the handling process will often lift out remaining bunt balls and keep the grain in condition.

Never contaminate or attempt to blend bunt-infected wheat with clean wheat. It takes very little bunt to downgrade the grain. Blending will simply contaminate the good grain, not improve the damaged grain. For more information, see Dwarf Bunt and Common Bunt.


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 30 April 2009
Last Reviewed: 30 April 2009