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3. Basic Soil Monitoring and Evaluation
Lab tests
For more detailed information on soil
health, send soil samples to a lab. New
Mexico State University has done extensive
research on effective soil indicators across
different land management scenarios
to find the most appropriate indicators
for soil health in New Mexico. Criteria to
evaluate these indicators included results
of multivariate statistics, discussion with
experts, precision of measurement method
to get repeatable results, relevance to
important functional soil processes, ease
and cost of sampling and analysis.
Best soil health indicators for arid systems
Characteristic:
Physical
Chemical
Biological
Dry aggregates
> 2mm (%)
Electrical conductivity
Soil organic matter
Clay content (%)
Phosphorus content
(mg/Kg soil)
Active carbon
(Permanganate
oxidizable carbon;
“POXC”)
Available water
capacity
Potassium content
(mg/Kg soil)
Wet aggregate stability
Other soil health indicators that were
considered included:
Physical properties
Mean weight diameter of dry aggregates
(mm), Dry aggregates less than 0.25mm (%),
Sand/Silt/Clay (%), Available water capacity
(cm
3
/cm
3
soil), wet aggregate stability, bulk
density (mg/m
3
), penetration resistance (psi),
pore size distribution, water infiltration rate.
Chemical Properties
pH, Electrical conductivity (EC; dS/m), Sodium
adsorption ratio (SAR; Saturated pasted for EC
and SAR is highligh recommended), Nitrate
(mg/Kg soil), Ca/Mg/Na/Zn/Mn/Fe/Cu, cation
exchange capacity, Toxins/Pollutants.
Biological Properties
Phospholipid fatty acid test, N mineralization
rate, decomposition rate, respiration rate,
earthworm counts.