Earthworm Distribution under Different Land Use Systems in Northeast of Thailand - Benefit for Land Resource Reclamation

<p>The aims of this paper were to study the influence of land use system type on earthworm distribution in Northeast Thailand. The experimental systems were a natural forest, a eucalyptus plantation and an organic agricultural and a conventional agricultural farming system. The effects of land use systems and their management on the distribution and characteristics of the earthworm, Pheretima sp. on related soil properties were investigated in the rainy season (August-September 2008) and the dry season (December 2008-February 2009) in Baan None Daung Mun, Tumbon Sa-Ead, Amphur Muang, Khon Kaen, Northeast Thailand. Earthworm populations varied and there were significant differences between systems (p<0.05). Numbers were highest in the natural forest followed by the organic agricultural system, lower in the conventional agricultural system and lowest in the eucalyptus plantation in the rainy season. The same result was found in the dry season but the organic agricultural system had a higher number of casts than in the natural forest. The same trend was found for earthworm cast height and cast width. The results showed that the earthworm cast width in the eucalyptus plantation was lowest in the rainy season but not significantly different in the dry season between land uses. These results suggest that land use type strongly influences the abundance and characteristics of earthworm casts in the various soil ecosystems. The results of soil analyses showed that the biological soil quality, measured as soil respiration, in soil samples from each land use type were not significantly different (p<0.05) from each other but was highest in the organic agriculture system and lowest in the eucalyptus plantation. The soil respiration in earthworm’s casts was higher than in soil in the rainy season. The results showed that the soil properties of earthworm casts were different in each land use system. Particularly, the increase of % silt and % clay and an associated decrease of % sand was found in the earthworm cast compared with the surrounding soil in every land use system. The results for soil quality showed that the earthworm casts had higher electrical conductivity (EC), organic matter, cation exchange capacity (CEC), total nitrogen, available phosphorus, and calcium and magnesium concentrations than found in soil especially the level of available phosphorus in casts.</p>