Crop residues and reduced tillage work together to:
- Enhance soil organic matter levels, moisture, and physical characteristics.
- Provide a unique micro-climate for crop seedlings (germination and emergence).
- Decrease overall weed pressures in a field.
To fully exploit all the agronomic co-benefits of direct seeding (no-till system), residue management (RM) must be compatible with continuous (annual) cropping, early emergence and successful maturity goals - all within unpredictable prairie weather.
Basic direct seeding RM implies excess crop residue (straw and chaff) and standing stubble will be handled without tillage. However -Harvest methods impact direct seeding. There may be degrees of difficulty and various solutions depending on the experience and skill of the farm-operator. The task is complex and must be flexible, practical and above all, affordable - or it won't happen. RM is where the real challenge of no-till and the true art and science of direct seeding meet!
Contemporary RM strategies and possibilities include:
• Combines with fine-cut straw chopping and/or chaff spreading capability; Straight-cut or "Stripper" headers
• Post-harvest and/or pre-seed harrowing (heavy harrows, etc.)
• Residue removal (feed crops; baling, chaff collection)
CAUTION: Harrowing Tips:
• Tractor Power - Speed must be sufficient to spread residue without bunching
• Residue must be dry and brittle. Some crop types are incompatible, ie: peas and flax
• Fall-harrowing minimizes stubble knock-down and surface mulch. Spring harrowing may compromise the pre-seed burnoff.
Other RM factors are:
• Rotation: crop choice (and yield outcome) determines residue quantity, quality, and ultimately the best practice for each case.
• Width of cut (swath, header size, etc.): significantly impacts combine capacity and spread pattern (adequate surface mulch distribution).
• Stubble height: standing stubble traps snow and improves moisture retention.
• Straight-cut vs. Swathed: taller stubble generally has less surface mulch to manage (soil warming, row spacing, seedrow width, etc).
• Conventional vs. Rotary combine: major differences for straw and chaff handling options!
Generally, although high-residue crops are favorable to build soil quality, managing large quantities of straw and chaff is not simple. Each grower must preferentially consider personal resources. Harvest decisions ultimately affect what direct seeding system works best overall, including seeding machinery features (ie: opener style, row spacing, fertilizer placement, field finish, etc.).
For example, consider 4 different cropping systems that may have 4 different RM practices based on farmer experience/opportunity:
• Farmer A always plans to heavy harrow wheat stubble in the fall in order to avoid problems direct seeding canola next spring.
• Farmer B sometimes bales straw for a nearby feedlot and likes to stubble-graze his cows.
• Farmer C straight-cuts where possible, with a fine-cut straw chopper and retro-fit chaff spreader.
• Farmer D collects chaff and straw in a high dump silage wagon pulled behind the combine.
Given all the advancements of no-till towards environmental competency and steadfast profitabiity, there remains one basic rule for its success overall - Respect of all things SOIL. Simplified, behind it all has been the ongoing quest for "residue-friendly" cropping systems.
