Indicator Time to test Healthy Condition
Earthworm presence When soil is moist >10 worms/ft3 castings in tilled clods
Color When soil is moist Topsoil remains darker than subsoil
Presence of plant residues Anytime Residue on most of soil surface
Conditions of plant roots Late spring or during rapid growth Roots extensively branched, white, extended into subsoil
Degree of subsurface compaction Before tillage or after harvest A stiff wire goes in easily to 2x plow depth
Soil tilth or friability When soil is moist Soil crumbles easily
Signs of erosion After heavy rainfall No gullies, runoff from field clear
Water holding capacity After rainfall during growing season Soil holds moisture at least a week w/o signs of drought stress
Water infiltration After rainfall Norunoff; soil surface does not remain excessively wet
pH Same time each year Near neutral and appropriate for crop
Nutrient holding capacity Similar time of each year N, P, and K stable and sufficient content
Table 1: Some indicator and tests for healthy soil.