Earth Worm for Soil Fertility
Physical side of the earthworm action
- The role that earthworms play in soil conditioning and fertility is underrated.
- The contributions of earthworms go unnoticed because they are not seen at work (most of them are night crawlers) and their influence on the soil-systems have not been carefully understood.
The activity of the earthworms is not limited to the top soil alone.
- Before proceeding on this, would like to engage you in an observation.
- Look for cow-dung droppings outdoors could be anywhere in the yard or in the streets.
- If you lift any dropping that’s a few hours old and examine the underneath you will invariably find at least 2 holes.
- These holes will be seen on the soil surface below the dung as well as the bottom surface of the dung.
- One is that of the beetle-bug and the other is that of the earthworm.
- Both burrow their way up from the deep soil enter the dung and then return.
- This happens even in the hardest surfaces.
- I have seen this even in semi-paved surfaces and broken concrete surfaces.
- The traces of the burrowed mud can be seen the dung.
- This demonstrates that earthworms operate below the top soil too.
Earthworms can be dormant and can remain deep in the soil.
- When soil conditions and environs are conducive they can travel their way up even from 15 feet and under.
In soils with fair amount of mulching there will a minimum of 4-5 earthworms in a square foot.
- This translates to 175000- 200000 earthworms per acre.
- Round it to 2 lakhs.
- No every worm digs 2 holes every day.
- It starts from the deep soil eats it’s way up deposits the casting on the top sail and digs it’s way back into the deep soil.
- Now this means that there are 4 lakh holes in an acre!
- Can you imagine the aeration water retention etc that happens because of these 4 lakh tunnels?
- Now during rainy season all the water collects in these holes and it’s deposited deep into the soil by gravitational force.
- After rain during summer all the water stores slowly comes up by capillary action when it comes up it brings up the mineral and nutrient elements in the lower layers of soil to the root zone.
- Studies have shown that earthworms improve the water absorption of soil up to 35 times.
In another study
- Soil in a field with 100 earthworms per square yard 2 inches of water (a very heavy rainfall) could be absorbed by the soil in 12 minutes.
- The same soil without earthworms took over 12 hours to absorb that much water.
Let’s not forget the chemical/biological side of it.
Soil passed through the earthworm intestines works magic. The castings formed are granule like do not dissolve in water and are easily absorbed by plants.
- 5 times more nitrogen,
- 7 times more phosphate,
- 11 times more potash,
- 2 times calcium and
- 4 times more magnesium than regular soil.
In addition to this beneficial bacteria and micro organisms are 13 times more in castings.
- decomposing bacteria,
- symbiotic and asymbiotic nitrogen fixing bacteria,
- azospirillium etc proving that earthworm intestines are amazing bio-reactors.
This apart, earthworms actually eat the bad microbes.(fungi, bacteria, etc.)
Tests have shown that crops grown in earthworm-inhabited soil increased yields from 25% to over 300% than in earthworm-free soil. ( K.P. Barley, Advances in Agronomy, vol. 13, 1961, p. 262-264)
In another study in America
- Soil samples from a field not fertilized for 5 years but with an active earthworm population was analyzed.
- Based on the reported analyses it was found that
100 tons of earthworm castings will contain
- 4 lbs. of nitrate nitrogen,
- 30 lbs. of phosphorus,
- 73 lbs. of potassium,
- 90 lbs. of magnesium,
- 500 lbs. of calcium.
- That is the equivalent to a 4-69-86 fertilizer
- And 3/4 ton of limestone worth $34.15 per acre with no fee for spreading or transportation.