Soil Health

Soil health is evaluated across three dimensions. Physical indicators include texture, structure, bulk density, aggregate stability, and infiltration rate — these govern water and air movement. Chemical indicators include pH, cation exchange capacity (CEC), macronutrients (N, P, K), and salinity. Biological indicators include organic matter content, microbial biomass, earthworm counts, and respiration rates.

The single best proxy for overall soil health is organic matter: fields with 3–5% soil organic matter retain 2× more water, supply 20–40% of their nitrogen biologically, and resist erosion far better than fields with 1% organic matter. Cover cropping, compost applications, reduced tillage, and crop rotation all build soil organic matter over time — typically 0.1–0.3 percentage points per year under sustained management.

Healthy soils are the cheapest resilience asset a farm owns. A 1% increase in organic matter holds an additional 150,000–250,000 liters of water per hectare, which directly buffers drought. USDA's Soil Health Assessment Framework recommends a standard soil-health test every 3–5 years to track progress. Farms that improve soil health typically see yield gains of 5–15% alongside 10–20% reductions in fertilizer and irrigation inputs (USDA NRCS, 2023).