Compaction can be a serious problem in a field, but determining where the worst spots of compaction are in a field isn’t that hard to do with your eyes.
When there is soil compaction, plants are going to be discolored and probably not growing very well. If you try to stick something in the ground, like a rod or soil penetrometer, compacted soil won’t make the task easy. If you dig around plants and notice that the roots aren’t very deep, follow the seed furrow, or abruptly turn instead of penetrating deeper, there is a good chance there is a compacted layer of soil.
The more scientific way of finding compaction is by using a soil probe (cone penetrometer) to probe different areas of the field, writing down and comparing the pressure it takes to break through the soil at different depths. This can easily be done in conjunction with GPS so you can overlay the data with your field maps to view where the issues are. While this is time consuming, it is important to know in order to set tillage tools at the appropriate depth. Rippers set too deep will slice through compaction zones without shattering the zone. Rippers set too shallow will not have any effect on the compaction zone. To be most effective, ripper should be set so that the point runs approximately one inch below the compacted layer. As a rule of thumb, most deep compaction zones occur in the 11-13 inch deep range.
Is it possible to tell all of this with yield maps or Normalized Difference Vegetation Index (NDVI) images instead of using probes? Compare your yields or NDVI images over time and notice if there is a pattern where a certain area is yielding poorly or slow to canopy; then go out and probe that area. You might also look to see if there are certain areas of your fields that aren’t draining properly or have excessive runoff, this could be a sign of compaction.
Compaction can typically be alleviated through tillage, but you need to decide where your compaction is before you get too carried away. If your compaction is in the top seven to eight inches of your soil, chisel plowing should be adequate. If it is deeper, subsoiling may be required. However, the better way to manage compaction is to prevent it. Avoid working soils or operating heavy equipment like grain carts and combines when conditions are wet.
[ PHOTO ]
Minimize traffic on the field – avoid “unload on the go” harvesting by keeping grain carts and trucks at the edges of the field.
Larger surface area – for all equipment, the larger the surface area of the tires/tracks, the better spread out the weight will be. This includes making sure your tires are properly inflated for the field, not the road.
Weight of machinery – some equipment is lighter than others. If your fields are prone to compaction, compare the weight of different machinery of the same capabilities to determine if there is a better option.
Use cover crops – not only do cover crops help with compaction by adding more organic matter into the soil, they also help hold soil in place, reducing soil loss. Cover crops also help with soil moisture if you farm in an area that is drier.
Minimize tillage for your operation – too much tillage can cause compaction as it can destroy the natural soil structure.