Straw and chaff spreaders
A straw spreader uses rotating blades or rubber batts to throw or deflect whole pieces of crop residue. While the spreader typically distributes the residue more uniformly, the straw chopper can provide more residue cover, since it chops the residue into small pieces before spreading.
A chaff spreader is effective in handling fine materials-primarily from harvest of small grains or soybeans. Chaff makes up nearly half of the harvested materials of some crops. It does not usually reach the straw spreader or straw chopper because it drops to the ground from the combine sieves. With high yielding crops, the

Chaff spreaders (bottom of photo) help ensure even residue distribution.

potential for creating heavy windrows is great. Chaff is easily distributed but because it's lightweight, it's hard to spread beyond 20-25 feet.
The most commonly used chaff-spreading attachments are hydraulically driven single or dual spinning disks that have rubber batts attached. Generally, single-disk spreaders are most effective for headers under 20 feet, while dual spreaders are more effective for wider headers.

Spreader caution
Be careful not to overcorrect for windrowing problems. For example, spreaders may be set to spread the crop material too far, which simply creates windrows outside the harvested swath.

For small grains:
Stripper combine headers may leave more of the residue standing than other types of combine headers. Standing residues capture more snow to increase soil moisture levels.

Residue decomposition
Rainfall, higher temperatures, fall tillage or knifed-in fertilizer applications can all speed the decomposition of crop residues between harvest and planting.
Breakdown rate also depends on the type of crop. Non-fragile crops like corn leave residues that are tougher to breakdown than soybean residues.
Time is also a factor in the decomposition of residue. A summer-harvested crop has more time to decompose than a fall-harvested crop.
As long as adequate moisture is available, decomposition can occur when temperatures are above 50 degrees Fahrenheit (10 degrees C). Even when air temperatures drop below freezing, snow can actually act as an insulator and allow decomposition to continue.
Here are crop residue types grouped by their relative decomposition rate:

Table 5. Crop Residue Decomposition Categories

Non-Fragile	Fragile
Alfalfa or legume hay Cotton Corn Forage seed Forage silage Grass hay Millet Oats* Pasture Popcorn Rye* Sorghum Tobacco Triticale* Wheat*	Canola/Rapeseed Dry Beans Dry Peas Fall-seeded cover crops Mint Peanuts Potatoes Soybeans Sugar Beets Sunflowers Most vegetables

* Residue from this crop should be considered fragile if a combine is used with a straw chopper or otherwise cuts straw into small pieces. If your crop is not listed, contact your USDA Natural Resources Conservation Service office for more information.