Milled cereal straw accelerates earthworm (Lumbricus terrestris) growth more than selected organic amendments

Tom Sizmur,Elodie Martin,Kevin Wagner,Emilie Parmentier,Chris Watts,Andrew P Whitmore

doi:10.1016/j.apsoil.2016.12.006

Abstract

Earthworms benefit agriculture by providing several ecosystem services. Therefore, strategies to increase earthworm abundance and activity in agricultural soils should be identified, and encouraged. Lumbricus terrestris earthworms primarily feed on organic inputs to soils but it is not known which organic amendments are the most effective for increasing earthworm populations. We conducted earthworm surveys in the field and carried out experiments in single-earthworm microcosms to determine the optimum food source for increasing earthworm biomass using a selection of crop residues and organic wastes available to agriculture. We found that although farmyard manure increased earthworm populations more than cereal straw in the field, straw increased earthworm biomass more than manures when milled and applied to microcosms. Earthworm growth rates were positively correlated with the calorific value of the amendment and straw had a much higher calorific value than farmyard manure, greenwaste compost, or anaerobic digestate. Reducing the particle size of straw by milling to <3mm made the energy in the straw more accessible to earthworms. The benefits and barriers to applying milled straw to arable soils in the field are discussed.

Highlights

Earthworms are the most abundant animal, by biomass, in most soils (Lavelle and Spain, 2001) and are responsible for providing numerous ecosystem services and functions (Blouin et al, 2013) that benefit crop growth (Bertrand et al, 2015)
Straw had no significant effect on the earthworm population in the Broadbalk experiment and there were no significant interactions between straw and farmyard manure on earthworm abundance or biomass
We found that straw increased the growth rate of L. terrestris to a greater extent than organic manures in the laboratory (Figure 3)

Summary

Introduction

Earthworms are the most abundant animal, by biomass, in most soils (Lavelle and Spain, 2001) and are responsible for providing numerous ecosystem services and functions (Blouin et al, 2013) that benefit crop growth (Bertrand et al, 2015). Earthworms increase the rate of water infiltration (Bouché and Al-Addan, 1997), the availability of nutrients (Devliegher and Verstraete, 1996), and can increase crop yield by 25% (van Groenigen et al, 2014). Many agricultural practices such as tillage (Chan, 2001), pesticide application (Pelosi et al, 2014), and the removal of crop residues (Karlen et al, 1994) decrease the biomass and abundance of earthworm populations. These parameters cannot be manipulated in field populations

Methods

Results

Conclusion