| A chaff spreader may be the least expensive conservation investment you ever
make. Chaff spreaders are not just for no-tillers. Chaff row problems can
occur in any tillage system. Chaff management begins with a proper spreader on the combine. Once on the
ground, chaff is almost impossible to spread. If simply dropped behind the
combine, it can cause a number of problems.
- Cold, wet conditions under the chaff row can delay
germination.
- Seeding equipment may plug and have difficulty
penetrating the chaff layer, resulting in uneven
placement and poor germination.
- Material in chaff rows can release substances toxic
to seeds and new seedlings.
- Delayed or slow crop germination gives weeds a head
start, results in uneven crop development and can make
straight combining impossible because of green strips in
the field.
Quick Facts
- A 40-bushel wheat crop can produce 1000 lb of chaff per acre (1123 kg/ha). If
you don’t spread the chaff, it falls in about a 5-foot wide (1.5 m) blanket
behind the combine. Reducing the swath width reduces the concentration of the
chaff.
- Cutting a crop higher will reduce the amount of straw to spread, but not
necessarily the amount of chaff. Standing stubble higher than 8-10 inches
(20-25 cm) can cause plugging problems with seeding equipment.
- Between 20 and 40 per cent of the material that enters the combine will pass
onto the sieve and out the back as chaff.
NOTE: Some producers prefer to collect the chaff for use as a livestock feed or
to minimize the spread of weed seeds. Determine whether spreading chaff or
collecting chaff is more feasible for your operation. Some chaff spreaders can
be used to either spread chaff in the field or blow chaff into wagons for
collection.
Use This Checklist
Chaff spreaders are now considered standard equipment on newer combines, but
some are manufactured by smaller shops for a variety of combines not originally
equipped with chaff spreaders.There are several items to consider when choosing a chaff spreader.
Width of Spread
Swath width will dictate how far you must spread the
chaff. Studies by the Prairie Agricultural Machinery
Institute (PAMI) indicate that a spread width of 40 per cent
of the swath is adequate but a 50 per cent spread is
recommended. For example, on a 30-foot (9 m) swath, a
15-foot (4.5 m) spread is recommended.
There are two basic methods of spreading chaff:
- Mechanical spreaders use spinning disks or paddles.
Maximum distribution can reach 20 feet.
- Pnuematic or air-driven spreaders use forced air
alone or in combination with mechanical means.
Generally, air assist spreaders will spread chaff up to
40 feet (12 m) or more, but also use more horsepower and
often cost more to purchase.
Uniformity of Spread
Most spreaders do an adequate job of distributing chaff
evenly, but talk to a chaff spreader dealer or manufacturer
or someone who owns a chaff spreader for more information.
Adequate Chaff Spread is Critical to Good Residue Management
Ease of Spreader Adjustment
Adjustment of spreader fins, deflector plates and speed
may be required depending on wind, dampness and amount of
material to spread. Adjustments to the spreader should
be quick and easy. Ease of Combine Adjustment and
Inspection
Easy access to the combine components is important for
adjustment and to sample grain loss. Some chaff
spreaders restrict access; some slide out of the way or
swing aside to provide access. Other Considerations
Mechanical chaff spreaders are either belt driven from
the combine’s mechanical system or hydraulically powered.
Horsepower requirements can range from either 0.5 to 35
horsepower, depending on the machine and crop conditions.
Tough harvesting conditions will generally require more
horsepower. Ease of installation may be important if you
plan to remove the spreader periodically.
Safety must always be considered when operating high-speed
equipment.
Costs vary from $900 to $5000 or higher, depending on the
size and complexity of the machine. If the machine is a
combination straw chopper/chaff spreader, take note of how
fine it chops straw as well as how far it spreads chaff.
Most spreaders are low maintenance machines with sealed
bearings. Belt tension may need to be adjusted
periodically. Homemade chaff spreaders are not uncommon.
Some producers have fashioned mechanisms that catch chaff as
it falls from the sieve and throw it with either spinning
disks or air. The principles of spreading and drive
power are essentially the same as those used in
professionally manufactured machines. If you plan to
build one yourself, make sure you consider the items listed
above. Chaff Spreader Directory
Summary of performance of spreaders tested by PAMI
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