Earthworms - Nature’s Soil Builders

Other than for fishing, I first became aware of the value of earthworms back in the 1960s.  Many farmers were then  beginning to transition from harsh NPK fertilizers to more natural soil amendments—lime, gypsum, rock phosphate, and manure. With the renewal of health in the soil, great numbers of the dormant earthworm eggs hatched.  I recall one incident where the migration of newly hatched earthworms onto the roads bordering the fields resulted in slick roads as the worms were crushed by the traffic.

Some points to ponder about earthworms:

  • Earthworms are damaged by deep cultivation, drought, toxic fertilizers, heavy metals, and most agricultural chemicals. 
  • Populations of earthworms may vary from 30/m2 in intensively farmed fields to 450/m in organic soils.  250 per square meter equals about a million per acre. A thriving earthworm population is an indication of healthy soil.  Healthy soil contains more life under the surface than can be grown above the surface.
  • Earthworms replenish the soil with their excrement.  Earthworm castings—the little piles of poop on the soil surface—are estimated to be tons per acre. These castings contain 3 times more available Calcium; 2 times more available Magnesium, 5 times more available nitrogen, 7 times more available phosphorus, and 11 times more available potassium than the soil they inhabit.
  • Earthworms burrow through the top layers of soil to reach a stable, damp depth.   These burrows aerate the soil  and allow deeper penetration by  plant roots.
  • A healthy soil full of earthworms can absorb up to 150 liters of water per  square meter per hour thus helping to prevent soil erosion.
  • The common earthworm feasts on rotting, bacteria-rich plant matter it finds on the soil’s surface.  To encourage earthworm populations farmers  should leave some plant residue after harvest and use a cover crop such as grass during winter to provide food for the worms.   
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Nature’s soil builders and rejuvenators—earthworms—are under threat.  Their population continues to dwindle because of industrial agricultural practices. 


Protecting these unsung  heroes of the soil as they work unseen and underground   should be an agricultural goal.