Handling Difficult Crop Residue Conditions in Direct Seeding Systems

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  Heavy straw cover after harvest | Crops still unharvested in the spring | Tips to reduce plugging during planting | Tips for next year

High crop yields and unusual weather often leave hard-to-handle crop residue conditions. These include:
  • crops not harvested due to hail, severe frost or other damage.
  • lodged or snow-flattened crops not picked up by the windrower or combine.
  • crops producing heavy residues such as viny pea crops, sunflowers and flax.
  • very tall stubble left by straight-cut or stripper-header operations.
Combine performance is reduced when very heavy crops are cut short and large amounts of crop residue must pass through the combine for chopping and spreading. Long stems or whole plants left unharvested can cause equipment plugging in subsequent operations.

When developing a residue management system that can handle difficult conditions, consider timeliness, economics, cropping plans, and conservation of soil and soil moisture. Your system must leave the field surface in good condition for subsequent equipment operations and for crop growth. Planters must be able to place the seed at the proper depth into moist soil with good seed-to-soil contact. Soil moisture must be conserved in case of dry spring weather. And, of course, reasonable costs must be maintained.

See also:
Residue Management for Successful Direct Seeding (Agdex 570-4) and Equipment Issues in Crop Residue Management (Agdex 519-4).

Heavy Straw Cover after Harvest

Harrowing to improve the distribution of straw and tilled stubble reduces plugging in planters. Although harrows sometimes do not appear to do much, they do spread straw, press loose straw into the soil surface, and disperse straw clumps. A fall harrowing operation and several spring harrowing passes may be needed on some fields. Heavy harrows under dry conditions will break stubble and straw. Rotary harrows may reduce but will not solve heavy residue problems. When chaff is a problem, harrows do not help.

Even very heavy residue or very tall standing stubble is not usually a problem if it is mowed or shredded. However, mowing costs about $5 to $7 per acre. Some farm supply outlets have mowers available for rent.

Rotary mowers are rugged enough to work close to the ground even in stony conditions. Flail mowers are more vulnerable to damage from stones and uneven ground. Clippers, which are sickle mowers like a grain windrower, are used to shorten tall stubble.

Mower performance is affected by the amount of crop residue, stubble height, the mower s height setting and its forward speed. To turn a heavy residue situation into a good planting condition, set the mower s blade height to 3 to 4 inches (8 to 10 cm) and its speed to 4 to 5 miles/hour (6 to 8 km/hour). A lower blade setting and slower travel speed will increase the fineness of chopping.

Mowers sometimes produce a slight windrowing effect. If this occurs, a harrowing pass may be needed. Mowing may also leave a thick mulch of residue on the soil surface. During planting, ensure the seed is placed in soil, not in mulch.

The first tillage pass after harvest leaves a very poor seedbed condition. If you decide to till, then you must use enough tillage to mix the straw into the soil so that planter ground openers will work without plugging.

Tillage reduces seedbed moisture while increasing soil erosion risk. Tillage in spring or fall should be followed by harrows or packers to reduce soil moisture loss.

Crops Still Unharvested in the Spring

Of course, harvest the crop if it is still valuable, setting the combine header height and straw spreader as required. Windrows of straw may be baled and removed (this works well for direct planting). After winter, straw and stubble are more brittle and may break up with mowing or several harrow passes (this works best on a warm, dry day).

Burning straw is a last resort option. However, for exceptionally heavy or tangled residues, burning may be a better choice than aggressive spring tillage.

Use a direct seeding planter to seed immediately after burning. Do not cultivate after burning (you do not want to invite a soil erosion disaster, too). Remember, this is a compromise to address an immediate problem; you need to take full advantage of any benefits available. Direct seeding into the shallow soil moisture, good seedbed and dark soil surface will promote quick crop emergence.

If you do burn:
  • Try to avoid having to burn again next year. Build other options into your residue management system to handle difficult conditions.
  • Check local bylaws; many municipalities require permits for burning.
  • Remember that burning can endanger property and life, and that there may be liability associated with fire and smoke hazards.
Tips to Reduce Plugging During Planting
  • Planter ground openers working in firm soil are less prone to plugging.
  • Planters handle crop residue best in warm, dry conditions.
  • Changing speed and direction of travel may help a planter to clear crop residue.
  • If plugging problems persist, try another harrow pass.
Tips for Next Year
  • Cut crops short enough so straw and stubble will pass through the cultivator or planter. Stubble height should be no longer than the shank spacing of the planter.
  • If your combine has sufficient capacity, use it to cut the crop to the proper height. Using the combine for this costs roughly $2 per acre; spring mowing costs about $5 to $7 per acre.
  • Install pick-up guards on the combine or windrower, so areas of lodged crop can be picked up and chopped by the combine.
  • Ensure that the combine s chopping and spreading equipment does its job well enough for the planter to clear the residues.
  • Harrow stubble fields to press the loose straw into the soil surface. This improves the flow of crop residue through the planter.
  • Loose straw may be baled if the total amount of residue is expected to cause insurmountable problems and if there is a use for the straw.
Prepared by:
Murray Green,
Engineering Services Branch,
Alberta Agriculture, Food and Rural Development

Source: Agdex 519-2. March 1996.
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This information published to the web on March 1, 1996.