Earthworm services for cropping systems. A review

Abstract

Intensive agriculture is often criticized for negative impacts on environment and human health. This issue may be solved by a better management of organisms living in crop fields. Here, we review the benefits of earthworms for crops, and we present techniques to increase earthworm abundance. The major points are the following: (1) Earthworms usually improve soil structural stability and soil porosity and reduce runoff. (2) Earthworms modify soil organic matter (SOM) and nutrient cycling. Specifically, earthworms stabilize SOM fractions within their casts, and they also increase the mineralization of organic matter in the short term by altering physical protection within aggregates and enhancing microbial activity. (3) The positive correlation between earthworm abundance and crop production is not systematic, and contrasting effects on yields have been observed. Earthworms induce the production of hormone-like substances that improve plant growth and health. (4) Direct drilling increases earthworm abundance and species diversity, but the beneficial effect of reduced tillage depends upon the species present and tillage intensity. (5) Organic amendments enhance earthworm abundance. (6) Earthworms feeding at soil surface are the most exposed to pesticides and other agrochemicals. Finally, we discuss how to combine management practices, including inoculation, to increase the earthworm services. We conclude that using earthworm services in cropping systems has potential to boost agricultural sustainability.

Humusica 1, article 2: Essential bases—Functional considerations

“…However, this soil quality does not depend directly from the number of individuals of earthworms but from the quality and quantity of the organic matter these animals are able to store in their droppings, which depends on the type of soil exploitation (e.g. use of pesticides, organic or mineral fertilisation, irrigation, type of culture, recent review in Bertrand et al, 2015). Even worse, to free the potential energy and nutrient content in the organic matter that earthworm activity could have stored in the soil, it is necessary to wake up microbial communities, purposely fed by plant exudates or even stimulated by a complex interaction with other organisms (Fitter and Garbaye, 1994;Blouin et al, 2013;Kardol et al, 2016).…”

Biocontrol of eyespot disease on two winter wheat cultivars by an anecic earthworm (Lumbricus terrestris)

“…Various strategies can be adopted (Bertrand et al, 2015), depending on the objectives of the farmer, from strategies involving minimal human intervention (such as the cessation of negative cultural practices, tillage or pesticide use or increasing the amount of organic matter returned to the soil) to strategies involving much higher levels of human intervention (use of earthworm-engineered products, such as vermicompost or vermicompost extracts), with intermediate techniques based on the inoculation of fields with earthworms or the transplantation of soil blocks (Blouin et al, 2013). Each of these techniques has been tested in only a few studies, in very different agronomic contexts, so it is not currently possible to identify the most promising techniques.…”

Earthworm Positively Influences Large Macropores Under Extreme Drought Conditions and Conservation Tillage in a Chinese Mollisol

“…In other words, this could be explained by the fact that earthworm can buffer the soil-plant system against the effects of extreme drought events (Johnson et al, 2011). Bertrand et al (2015) also noted that aboveground biomass generally increases in the presence of earthworms in extreme weather events.…”

“…One of the major ecological factors influencing soil porosity, especially macroporosity, is the burrowing activity of the earthworm (Maboeta et al, 2008). Numerous studies have emphasized that earthworms can greatly affect soil macroporosity (Bertrand et al, 2015). However, the extent of this effect on soil macroporosity is still somewhat vague, and very little is known.…”