Earthworms: Nature's free fertilizer?

Earthworm presence in the soil increases crop yield, shows a new study that was published this week in Scientific Reports. "This is not unexpected", says Jan Willem van Groenigen, associate professor in the Soil Biology group of Wageningen University, and lead author of the study. "People have known for millennia that earthworms can be good for plant growth. However, we did not know how strong this effect is, nor how it works. That is what we studied."

Van Groenigen and his MSc student Hannah Vos, co-author of the study, gathered all published articles to date on this topic: 58 different studies, the oldest one dating from 1910. All experiments measured the effect of earthworms on crop yield and plant biomass. Subsequently, Ingrid Lubbers, postdoctoral researcher in the Soil Biology group and co-author of the study, was able to discern patterns in the large amount of data, using a statistical technique called meta-analysis.

The overall outcome of the study was very clear: "On average, earthworm presence increases crop yield by 25% and aboveground biomass by 23%" says Ingrid Lubbers. "We also found that earthworms did not change the nitrogen content of plants, indicating that crop quality was unaffected. Earthworms therefore have a strongly positive effect on crop production".

Click here to read the complete article at wageningenur.nl.