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Competency Area 5: Soil conservation AEM

PO 53. Understand the relation between tillage systems and:

  1. Soil structure and compaction
  2. Runoff and erosion
  3. Use of fertilizers and pesticides
  4. Infiltration and percolation

Soil structure and compaction

Tillage destroys soil structure, although in cases it may enable crop roots to occupy compacted soil, which could help to build soil structure. Soil compaction is created below various tillage tools (i.e., plows, disks, powered rotary tillers), but it can also be alleviated by other types of tillage tools (i.e., subsoilers, chisels).


Runoff and erosion

Soil tillage increases runoff and erosion because of its effect on residue cover and soil aggregation. In certain cases where soil structure is poor or compaction is present, soil tillage may increase infiltration and reduce erosion. The goal of soil management should be however, to avoid relying on a cycle of tillage to remediate poor soil structure caused by tillage.


Use of fertilizers and pesticides

The major goal of tillage is to control weeds. In the absence of tillage, herbicides are needed to control weeds in permanent no-tillage. However, herbicides are only one tool in the box of weed control. Judicious use should be made of different herbicide modes-of-action, timing of applications, crop rotations, crop vigor, nutrient placement, mowing, reducing weed dispersal, etc., instead of relying on herbicides alone for weed control in continuous no-tillage.  In reality, herbicides are used by almost all non-organic farmers, and herbicide use is not increased greatly in no-tillage. Use of other pesticides is not greatly affected by tillage.


Infiltration and percolation

Crop residue cover helps to improve infiltration by the reduction of sealing and crusting. Percolation is improved when a well-developed, continuous macro-pore systems is present. Because macro- and microbial activity is significantly higher in permanent no-tillage systems than in plow-tillage, percolation is also customarily increased. Mulch till and ridge till would be intermediate, whereas zone-till is similar to no-tillage.