PL SC352 Study Guide - Final Guide: Tillage, Soil Horizon, Crop Residue
30 Apr 2018
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Mechanical Weed Control
- one of the principle means of weed control
- includes physical removal of weeds by
o hoeing
o cultivation
o machine removal
o flaming, steaming, etc
- also includes physical crushing or removal of weed seeds (harvest weed seed
management)
Tillage
Major advantage: weed control
- secondly preparation of seed bed, uniformity for small seeded crops
Tillage + cultivation influence weeds in 3 ways:
1) Uproot dismember and bury growing weeds and dormant perennial roots &
rhizomes
2) Change the soil environment in ways that can promote germination and
establishment or (less commonly), inhibit germination
3) Move weed seeds and propagules vertically and horizontally
- Tools used for tillage are unique, working depth (invert the soil profile), breakup
soil aggregates and shake weed roots free from soil
o cutting discs, shovels, press wheels
Tillage and perennials
- cultivators: degree of soil mixing depends on angle of the blade
o sever the roots of large weeds, uproot small weeds and bury both
- disc + rotary tillers chop up weeds, crop residues and mix with soil
- mid way in the life cycle, tillage is usually fatal
o some annual grasses are more difficult to control
- deep rooted perennials controlled by exhaustion of root reserves
o replacement of shoots removed by tillage
o enhanced by tillage following seasonal exhaustion of root reserves
- shallow rooted perennials are fragmented by tillage
o short term benefit: fragments may be dispersed and propagated by tillage
- some roots and rhizomes can be dessicated at surface or killed by freezing
- bulbs usually not effected by tillage
- uprooting a taproot NOT an effective method of control
- repeated tillage over 2 or more growing seasons may be required (every 2-4
recommendation)
- interaction between
o the tool
o timing
o biology of the weed
- determines the effects of mechanical weed management
- MOST effective when multiple tillage operations are performed over time
o shallow cultivation: can kill small seedlings
o inter-row cultivation: can dig out weeds, throw soil over small ones
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
One of the principle means of weed control includes physical removal of weeds by: hoeing, cultivation, machine removal flaming, steaming, etc. Also includes physical crushing or removal of weed seeds (harvest weed seed management) Secondly preparation of seed bed, uniformity for small seeded crops. Tools used for tillage are unique, working depth (invert the soil profile), breakup soil aggregates and shake weed roots free from soil: cutting discs, shovels, press wheels. Cultivators: degree of soil mixing depends on angle of the blade: sever the roots of large weeds, uproot small weeds and bury both. Disc + rotary tillers chop up weeds, crop residues and mix with soil. Mid way in the life cycle, tillage is usually fatal: some annual grasses are more difficult to control. Deep rooted perennials controlled by exhaustion of root reserves: replacement of shoots removed by tillage, enhanced by tillage following seasonal exhaustion of root reserves.
