Soil health: Indicators and improvements

March 1, 2019 – Issue 3

The following article is based on this Canola Watch podcast with University of Manitoba soil scientist David Lobb.

Soil health indicators that farmers can easily track are:

Organic matter. Organic matter can improve water-holding capacity, biological activity and nutrient mineralization, all indicators of soil health that can improve crop performance and reduce input costs per bushel. Organic matter is easier to measure than these other individual factors, making OM a useful benchmark indicator. Track OM over time by comparing soil tests from hill tops, side slopes and low areas. Use GPS to collect samples year after year from the same relative areas. Keep records.

Crop performance. What is happening to overall yield relative to the inputs applied? Yields may be going up over time, but if the volume of inputs required to achieve those yields is going up on a per-bushel basis, this could be an indicator of declining soil health. This is where field yield maps and profitability maps could help show areas where yield per input dollar is shrinking. Lower producing areas can be the result of many causes, but soil health could be a major one often overlooked.

When soil sampling to monitor soil health, compare OM for the top 6”, which is more likely to change with changes in surface applications of tillage and manure, and for 6” to 24”, which is more likely to change with changes in crop rotations (biomass-creating crops such as perennial forages) and higher yields (which mean more root mass).

How to improve soil health?

  • Adopt reduced or zero tillage to curtail the erosion that leads to the most rapid soil degradation, especially to high ground.
  • Target manure applications to low OM areas, especially hill tops.
  • High yielding crops will increase the biomass accumulation in the root zone.
  • If areas of the field are so degraded that profitable production is no longer possible, consider putting those fields into a perennial grass. It may take a few years to see significant soil health improvements from the grassed areas, but this will stop further degradation and directs input dollars to acres that actually making (not losing) money.
  • Move soil from low areas to hill tops. After decades of soil erosion, some fields have hill tops that can barely produce a crop because all of the topsoil is piled up in the low areas. As David Lobb describes in the last part of the podcast, the major job of moving that soil back to the hilltops is being done by some farmers and with positive results.
Canola Watch