Some time ago there was a paragraph in an article by Devinder Sharma, “about no tillage . . . [a method] based on minimal soil disturbance, organic residue retention and crop rotations. It is believed that the shift to zero tillage or minimal tillage will not disturb the soil, and therefore help in conserving natural resources. I’ve always thought earthworms were nature’s tillers, so it’s not clear to me exactly what zero tillage would amount to, since the earthworms would go on tilling anyway, unmindful of new agricultural terminology. Bhaskar Save tells us that earthworms turn around 6 tonnes of soil in its short lifespan. Zero tillage sounds unfamiliar in the Indian context!”[ Bhaskar Save’s farm, on the west coast of the Gujarat, Maharashtran border has been cultivated organically for fifty years.]
The paragraph triggered dim memories of a conversation with Winin Pereira about earthworms and led to a database search. There were only two useful references – the first was in the New Scientist’s review of a 21-year study carried out by the Research Institute of Organic Agriculture in Frick, Switzerland. One finding was the improved quality of the soil under organic cultivation, which could ensure good crops for decades. Organic soils had up to three times as many earthworms, twice as many insects and 40% more mycorrhizal fungi colonising plant roots.
The second reference was in a report of the WIDE Initiative’s findings relating to Water-efficient Sugarcane Farming, by Claude Alvares who published Winin Pereira’s last book: ‘Inhuman Rights’.
It presented a case study about Suresh Desai, a conventional farmer, who originally relied on synthetic fertilisers for raising his crops on his six acres of irrigated land and records that eventually he decided to stop using chemical fertilisers and pesticides because he was convinced they damaged the environment and affected public health.
He evolved an organic farming system for growing sugarcane which – after six years – developed a rich, loamy layer of soil, densely populated by earthworms and beneficial fungi, that not only retained the moisture received through the irrigation channels, but circulated it to areas not served by the water channels. As the population of earthworms increased, moisture percolation and aeration improved and far less water was used.
An online search reveals many papers on the subject – some finding that earthworm activity also sequesters carbon. One notes that atmospheric CO2 enrichment stimulates the activity of earthworms and also leads to more sequestration of carbon in earth’s soils, thereby reducing the potential for CO2-induced global warming.
In ‘Tending the Earth’ [p203], Winin noted another ongoing contribution by the earthworm and other creatures in the soil: they increase the soluble nitrogen and the available minerals in the soil. Even after death their decomposition continues the process.#