Measuring soil healthDOWNLOAD FILE
Top soil health challenges
- Nutrient management
- Soil compaction
- Poor crop emergence, disease
- Poor water infiltration, moisture
- Poor pore structure (no tilth)
Soil health is defined as the ability of a soil to function
- Crop yield over time and high response to inputs (fertilizer, seeds)
- Healthy root systems Nutrient supply for crops
- Minimal nutrient losses through leaching or volatilization
- Minimal erosion, resilience to loss from intense rainfall,
- Water management:
- Infiltration fast, water doesn’t pond
- Water storage high, crop resilience to dry spells
Soil organic matter and soil carbon
- Soil organic matter is closely related to soil organic carbon
- Soil organic matter also includes hydrogen, oxygen and nitrogen and is commonly measured by ignition in a very hot oven (loss = burned up organic material)
- Soil organic carbon = Combustion or Walkley Black hot acid method Multiply soil carbon X 1.72:
Organic matter (%) = Total organic carbon (%) x 1.72
Soil monitoring LAB: goals and timeframe
What is the primary goal?
- Crop health?
- Conservation of soil water and nutrients, efficient use of inputs?
- Environmental protection?
What is the timeframe?
- Soil organic matter (organic carbon) requires five or more years to measure change accurately!
- Crop yield varies with weather and may take five or more years to detect trends, increasing or decreasing
- Pests and diseases: variable occurrence
Monitor your soil: make a plan
- Observe crops above and BELOW ground
- Notice how crops respond by zone not just the field
- Test your soil the same time each year
- Set goals and build your soil
Soil health: sample consistently & dig deep
- Sample at the same time of year, use same tests over time
- Less frequent, many samples better practice (once every ~four years comprehensive and include deeper soils, fence rows and multiple zones)
- Combine five or more samples - shovel or auger samples in a bucket per zone sampling, mix well and subsample
- Take samples from plow layer, plus deep subsoil samples
- Dig a pit and make observations, or use a fence posthole
Rules of thumb for measuring soil health
- Set your goals (nutrient supply, root health, soil organic matter, which is most important?)
- Be Consistent (sample same zones, same time of year spring or fall, use same soil health tests, same laboratory)
- Be Patient (often takes four or more years)
- Use Benchmarks (fence rows, natural areas)