According to a new study, earthworms could potentially replace some high-cost mineral/synthetic fertilisers.
Researchers at UCD have gained a fresh insight into the soil dweller’s importance for crops taking up nutrients.
Their findings suggest what they regard as a “shortcut” in the soil nitrogen cycle not previously recognised in which earthworms.
They found that earthworms rapidly enrich soil and plants through nitrogen they excrete in their mucus.
Earthworm presence in the soil increases crop yield in the long run, through their burrowing and feeding.
According to researchers, this:
- Creates a good soil structure;
- Releases nitrogen that is otherwise locked away in soil organic matter.
Under laboratory and field conditions, a team of researchers from Ireland, Germany and China tracked the nutrient transfer from earthworms into the soil, wheat seedlings, and greenflies (aphids) using a method called stable isotope tracers.
They found greenflies acquired earthworm-derived nitrogen just two hours under laboratory conditions and after 24 hours in the field.
Researchers were astonished just how fast worm nitrogen moved through the soil, to roots, into plants and into the insects feeding on plant sap.
According to the paper, this suggests that earthworms probably supply nitrogen directly to crops.
Professor Olaf Schmidt from UCD School of Agriculture and Food Science said:
“The real novel insight we found is that nitrogen from worms is going into crops really fast.”
“Up to now, we assumed this involved slow decomposition processes and microbial cycling.”
“But our experiments show that nitrogen (N) and carbon (C) movement from living soil animals to plants can be extremely rapid,” he added.
“They do it exactly when crops need it most because. Earthworm activity and crop growth are sort of synchronised, by environmental factors, mostly temperature and moisture.”
Researchers believe that the newly discovered benefits could be particularly significant in farming systems trying to reduce the use of synthetic fertilisers.
They are of the view the agricultural sector should maximise the financial benefits of this nitrogen earthworms supply as a potential alternative to synthetic fertilisers.
Replace some fertilisers
Professor Schmidt stated that this work could inform how farmers manage land, soil life and nitrogen supply.
He said that by adopting cropping practices that promote earthworms, these dynamic nitrogen benefits will also be maximised.
“We knew from previous research that good earthworm populations contribute agronomically significant amounts of nitrogen to the soil. However, we did not know that they can supply crops with nitrogen in such a dynamic fashion.”
“Farmers cannot always know in advance when to apply mineral/synthetic fertilisers because crops may not need nitrogen if it is too cold or too dry, and then the applied expensive nitrogen is lost to the environment, as nitrate leached down into groundwater or as nitrogen gases emitted into the atmosphere.
“All forms of nitrogen supplied naturally, from the soil’s own stores, through decomposition and mineralisation, are economically and environmentally highly valuable and desirable, so we should maximise them,” he added.
“I don’t think earthworms will replace all mineral and organic fertilisers. However, their full use as a natural nutrient supply could offset the use and cost of mineral/synthetic fertilisers.”
“All in all, this is another new reason why we should work more with soil biology and encourage the use of soil organisms like earthworms.”
“Our land use and farming methods will be more environmentally sustainable and also more economical because we can save synthetic fertilisers.”