Different effects of earthworms and ants on soil properties of paddy fields in North-East Thailand

Abstract

As soil engineers, earthworms and ants play major roles in soil functioning, especially in modifying soil physical and chemical properties. This study was conducted in a very constraining environment, i.e., paddy fields which have anoxic conditions (approximately four months per year), and which are affected by soil salinisation during the dry period (approximately eight months per year). This study points out that despite those very adverse conditions, soil invertebrates must be taken into account in the dynamic of soil organic and mineral properties in paddy fields. The effects of one earthworm species, Glyphodrillus sp., and an ant species, Epelysidris sp., on soil physical and chemical properties were determined through elemental soil physical and chemical properties (texture, pH, conductivity, C and N contents) and near infrared reflectance spectroscopy (NIRS) in order to evaluate their ability to influence soil organic matter quality. PCA processed with NIRS data clearly showed that biogenic structures (ant sheetings and earthworm casts) were separated from the control surrounding soil. Earthworms and ants affected differently soil properties. Glyphodrillus sp. increased the SOM content and decreased the pH on the surface of the soil. These effects were attributed to an increase in fine particle content (clay). Conversely, Epelysidris sp. only increased the content of coarse particles (sand) and did not influence either soil pH or SOM content. Soil conductivity was found to be very variable but was not significantly affected by soil invertebrates. These results show the potential of soil macro-fauna to create heterogeneity at small spatial scale and to modify the quality of surface soils even under adverse conditions like saline paddy fields

Termite mounds and dykes are biodiversity refuges in paddy fields in north-eastern Thailand

“…Jouquet et al . (2008) previously reported the possible effect of ants and earthworms on soil particle size and soil organic matter dynamics in paddy fields in the same study area. In Indonesia, Widyastuti (2002) also demonstrated that soil macrofauna plays an important role in promoting litter decomposition and mineral nitrogen dynamics.…”

“…Few studies have examined the impact of soil macrofauna in the functioning of partially flooded ecosystems such as paddy fields, although ecosystem functions and services may be influenced by its biodiversity. Jouquet et al (2008) previously reported the possible effect of ants and earthworms on soil particle size and soil organic matter dynamics in paddy fields in the same study area. In Indonesia, Widyastuti (2002) also demonstrated that soil macrofauna plays an important role in promoting litter decomposition and mineral nitrogen dynamics.…”

New species of semi-aquatic freshwater earthworm genus Glyphidrilus Horst, 1889 from Thailand and Laos (Oligochaeta, Almidae)

“…This demonstrates that the species is compatible with at least organic farming and that conservation of the species is not difficult, which is increasingly important in the world. Jouquet et al (2008b) showed the casts produced by Glyphidrilus sp. can be considered as patches of nutrients in paddy fields.…”

Biogenic structures in soils under a primary Atlantic Rain Forest in SE-Brazil

“…This finding suggests that there is no selectivity in relation to the mineral particles size ingested by the worms, at least within this study area. A greater proportion of fine fraction materials have been reported in casts relative to undisturbed soil; however, the intensity of this granulometric selection likely depends both on the pre-existing soil texture as well as on the ecological behavior of earthworms (BLANCHART et al, 2004, RUIZ et al, 2006JOUQUET et al, 2008). However, only large earthworm casts and their sand, silt, and clay fractions were analyzed here.…”