We are asked all the time about earth worms. Most of us don’t think of them until it is time to go fishing, but earth worms may be the most important livestock on your farm. Jerry Brunetti, world renowned consultant calls them the "chicken-cow"of the soil. They have a gizzard to grind soil and plant particles, but they don’t eat the ground soil. They regurgitate the this mess into their tunnels where this mucousy concoction is fed on by bacteria and fungus. It is this microbiological smorgasbord that the worm actually eats!
How Many Worms Should You Have?
25 earthworms per square foot of soil equal 1 million earthworms per acre. Studies in England have shown that in healthy soil forty tons of castings per acre pass through earthworms bodies daily. A new USA study indicates 1½ million worms per acre which move 20 tons of earth each year. Studies by the National Soil Tilth Lab have shown that with good food sources and favorable conditions, a field might have over 100 worms per square yard.
Just like cattle and chickens, worms produce high quality fertilizer, but they take it a step further and happily till your fields.
This plowing by tunneling provides the soil with passageways through which air and water can circulate. This is important because soil microorganisms and plant roots need air and water just like we do. Without some kind of plowing, soil becomes compacted, air and water can't circulate in it, and plant roots can't penetrate it.
This tunneling activity helps breakup hardpan and other compacted soils. Studies have shown that 30% of a fields respiration during cold wet winter-spring months are due to earthworms. Another study in European orchards found that earthworms could increase the pore space in soil by 75-100%
More than simply plowing the worms are depositing fertilizer. This is something we should appreciate because earthworm droppings -- called castings is some of the highest quality fertilizer available. The weight of casts produced from all this burrowing and feeding may be greater than 10 lb per worm per year, in itself an indicator of why it pays the gardener or farmer to keep worm populations high.
An analysis of worm castings when compared to the parent soil shows:
- 7 times the available phosphorous
- 6 times the available nitrogen
- 11 times the available potassium
- 3 time the available magnesium
- 2 times the available carbon
- 1.5 times the available calcium