This document discusses soil health and how it relates to agriculture. It covers several topics: 1) Soil health tests evaluate soil physics, chemistry, and biology to assess the living system of soil. Traditional soil tests only consider physics and chemistry. 2) Increasing soil organic matter by 1% can increase crop yields by 12% and water holding capacity by 22,000 gallons per acre. Tillage and monocropping decrease organic matter over time. 3) The Soil Health Index evaluates indicators like soil respiration and water-soluble carbon and nitrogen to assess the soil's ability to support plant and microbial life. Comparing scores over time or between fields allows assessment of soil management practices.

1. Soil Health: physics
Traditional soil test = soil physics + chemistry
Soil = Living System
Soil health test = soil physics + chemistry
+ biology

2. Soil Health: chemistry

3. Soil Health: biology

4. Soil Health & Ag
 Crop yield potential in a field increases ~12% for every 1%
increase in OM.
 Barley yielding 50 bu/acre at a 0.5% OM expect to yield 56
bu/acre at a 1.5% OM.
 Increasing OM by 1% - adds ~ 22,000 gallons of additional
water capacity/acre.
 Southern Idaho’s low rainfall and reliance on irrigation
 Tillage, monocropping, and overapplication of fertilizers
decrease soil OM overtime. Continuous tillage -> soil loosens
to smaller aggregates -> erosion, nutrient/water runoff.
Soil OM affects soil properties
(structure, moisture retention,
biological activity, and plant
nutrient availability)

5. Idaho Soil
Health & Ag
In ID, lower OM, higher OM
depletion rates, greater soil
susceptibility to compaction,
and higher soil fragility index
are closely associated with
agricultural activity.
Soil
OM
OM
loss
Soil
Comp.
Soil
Fragility

6. Soil Health parameters and SHI
 Evaluates soil health indicators ( soil respiration (Solvita
CO2 burst test), water-soluble organic carbon and organic
nitrogen and their ratio-> indicate amount of food readily
available to soil microbes and plants
 Other: nitrate, ammonia, phosphate, aluminum, iron,
phosphorus, calcium, magnesium, and sodium.
 Soil Health Score/Index: calculated based on soil respiration
and water extractable carbon and nitrogen.
 SHI can be used to compare:
 a specific field over time, or
 between fields.
 The goal - to improve the soil health score by utilizing soil
building practices such as no-till and cover crops.

7. SHI - challenges
 Soil health test - methodology requires standardization.
Specifically: carbon dioxide evolution method require
optimization for moisture content, temperature and labware to
resolve performance issues.
 Methods require cross-lab validation to resolve intra-
laboratory issues, and lab performance testing to assure quality
soil analysis data.
 Extensive field calibration research is required to validate test
interpretation.
 Cost: $50 - $100/sample