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3. Basic Soil Monitoring and Evaluation
Sample Depth
Within a given area, you will have to decide what depths to sample. Again, your decisions will relate
to your goals. Whatever depth you choose, be sure to write down to the depth which you sampled
and why so that you can be consistent when sampling again in the future and better able to interpret
your findings.
Some questions to work through when making your decision:
1.
Which horizons are important?
2.
What is the management history of your site? How might it affect the different soil depths?
3.
What are the rooting depths of the plants at this site?
4.
Are you looking for deep compaction?
5.
Do you have an orchard or vineyard? Spatial variation in the lateral direction can be very high
in orchards.
6.
Do you use irrigation? If so, you may have salinity accumulation in different locations.
•
Flood – Salt can vary from the head to the foot of the field.
•
Micro sprinklers – Salts accumulate at the extremities, especially if not overlapped.
•
Furrow irrigation – Salts accumulate on ridges due to evaporation.
Note: Never include salt crusts in a soil sample; instead, sample the salt crusts separately if
needed.
7.
If you don’t have an explicit reason for sampling a given depth, it is common to sample 0-6
inches and 6-12 inches. Emerging carbon markets may require deeper sampling, and it will
be essential to follow their specific protocols.