Earthworms and pasture fertility - Establishing Optimum Numbers of the Ultimate Workforce, by Vaughan Jones, Acres USA, Oct, 2006
“It may be doubted whether there are many other animals which have played such an important part in the history of the world as have these lowly organised creatures,” Charles Darwin wrote in 1881. Darwin pointed out that humans would not have developed and would hardly be able to survive on earth if it were not for earthworms turning the forest leaves and pastures dead leaves into topsoil. Julius Caesar identified earthworms as beneficial and declared them protected.
It is a pity that many conventional farmers today have forgotten what people knew so long ago. Earthworms are animals that consume soil, animal manure, dead plants and organic matter and excrete it either in soilsor in casts above the ground. Analysis of castings shows that both the phosphorus, sulphur and potassium levels required by some soils for maintenance, and their casts are in a form easily available to plants.
In fact, the earthworms themselves are concentrated fertilisers, (they enhance the mineral content of the soil by 300%). Being composed of 0.86% potassium, 0.85% phosphorus and 0.82% sulphur, when they die, they supply these elements to the soil.
Each day earthworms consume up to a third of their weight in soil, decomposed dead animals (which is better than fly maggots doing so and becoming flies), manure and dead pasture, and the thatch layer on sodbound pastures then excrete it in casts. Each year they produce up to 32 pounds per acre of nitrogen, 13 pounds of phosphorus, potassium and sulphur in plant available forms. These levels are all that is required by some soils for maintenance.
Earthworms don’t have teeth or eyes, but they are light sensitive. They have a gizzard that uses fine sand, rockdust and agricultural lime, if available, to grind up what they eat. They also produce a very strong acid to aid digestion. They have both male and female sexual organs (hermaphrodites), but most species still require a partner for breeding.
Earthworms don’t have a nose or lungs – they respire through their skin, and therefore require humid conditions to prevent drying out. They coat themselves in mucus to enable the passage of dissolved oxygen into theirbloodstream. Without adequate calcium from lime they cannot make mucus.
There are about 3,000 species of earthworms in the world, but only a handful are common in any one area. Some reach maturity in less than a year, and some live for nine years. Populations are highest on soil with animal manure and dead vegetation on the surface.
Cultivation halves earthworm numbers as compared with no-till. Earthworms can produce up to 30 metric tonnes of castings per hectare per annum and lay about 30 cocoons a year.
Agrissentials Rok Solid Full Spectrum Fertiliser is ideal as all minerals are in a natural form.