Soil health metrics that are understandable, affordable, and linked to agroecosystem functions have the potential to guide producers in selecting and evaluating agricultural practices while demonstrating outcomes to buyers or potential certifiers. The imperative to improve and protect soil health has manifested in pressure from retailers to adopt so-called “regenerative farming practices”. While regenerative agriculture is not precisely defined or codified, soil management principles associated with regenerative agriculture include: maximize soil cover, minimize disturbance, maximize living roots, incorporate biodiversity, and integrate animals. Agricultural stakeholders in Washington State need robust metrics to complement and guide an outcomes-based approach toward regenerative or sustainable agriculture.
The concept of healthy soil is intertwined with the soil food web, though describing and managing an ideal food web is elusive. The soil food web supports plant and animal productivity and health through specific functions such as biological nitrogen fixation, nutrient cycling, plant pathogen control, and aggregate formation. Healthy soils reduce agricultural externalities caused by erosion, nutrient loss, and even greenhouse gas emissions.
In-house soil health analyses
Soil biology
Soil analyses in our current Long-term Agroecological Research and Extension site do not include extensive soil biological analyses. In previous studies, we have evaluated earth worm biomass, nematode diversity and abundance, microarthropod diversity and abundance, and microbial biomass.
Soil biochemical
We analyze mineralizable carbon using a 24-hour respiration. Initial and final CO2 concentration is determined with an infrared gas analyzer.
Soil Physical
Soil physical attributes analyzed in most of our studies include soil bulk density and penetration resistance. We are also analyzing saturated hydraulic conductivity in the LTARE.
Soil Fertility
Soil fertility analyses are primarily analyzed in commercial laboratories. Following sampling and air drying (in most cases) we homogenize soil and send samples for analysis of available soil nutrients or total elemental analysis.