Casting Activity ofScherotheca gigasin No-Till Mediterranean Soils: Role in Organic Matter Incorporation and Influence of Aridity

Paloma Bescansa,Iñigo Virto,Alberto Enrique,Oihane Fernández-Ugalde,María José Imaz

doi:10.1155/2010/526934

Paloma Bescansa, Iñigo Virto + Show 3 more

Open Access

https://doi.org/10.1155/2010/526934

Copy DOI

Abstract

The behaviour of earthworms, their role in organic matter incorporation into the soil, and the influence of aridity in such processes in arid and semiarid regions have scarcely been studied. In this study, physico-chemical analyses of the casts and the surrounding no-till agricultural soils of three experimental sites representing an aridity gradient in Navarre (NW Spain) were done. The casts were formed by the activity of the only anecic species,Scherotheca gigas(Dugès, 1828), ubiquitous in no-till soils in this region. We observed a significant depletion of clay and higher concentration of total organic C and labile C in the form of particulate organic matter (POM) in the casts as compared to the surrounding soil, suggesting selective ingestion of soil byS. gigas. This, together with the observation of increased concentration in POM with increasing aridity, suggests a major role of this species in the observed progressive gains of organic C stocks in no-till soils in the region.

Highlights

It is well known that the abundance of earthworms in the soil depends on soil properties and on climate
It was observed that S. gigas was the only anecic species found, which indicates that surface casts present in the three soils were created by individuals of this species
Our findings support the suggestion of Schrader and Zhang [27] that selective particle ingestion by earthworms leading to increased clay contents in casts than in the surrounding soil [28] appears to be confined to sandy soils, and/or might be more common in other smaller species of earthworms than the anecic S. gigas

Summary

Introduction

It is well known that the abundance of earthworms in the soil depends on soil properties and on climate. Most of the studies related to the earthworms behaviour are from the tropical and subhumid temperate soils. Their behaviour in more limiting conditions, such as agricultural soils in semiarid or arid regions, has been less studied [1]. The reality is that in the majority of agricultural soils with Mediterranean type of climate, like in the Ebro Valley of Spain, located in the Mediterranean-IberianLevantine biogeographical superprovince [2], earthworms are scarce and often absent when tillage is intense [4]

Objectives

Methods

Results

Conclusion