The objective of this study was to assess the influence of
earthworms and termites, as key soil bioturbators on soil hydrodynamics,aswellassoilandnutrientlosses.Rainfallsimulationswere
conducted in a steep slope fallow in northeastern Vietnam on 1-m2
micro-plots, which differed in the proportions of earthworm casts
and termite sheetings. Our hypotheses were that (i) an increase in
soil engineer abundance results in a concomitant enhancement of
water infiltration and soil detachment rates and (ii) the soil microrelief created by earthworm and termite bioturbation significantly
influences water runoff intensity, soil detachment rates and nutrient losses. We expected that highly stable earthworm casts would
increase water infiltration and decrease soil detachment, whereas
sheetings produced by termites are more prone to fragmentation
and would thus increase soil detachment. As a consequence we
assumed that earthworms favor the retention of nutrients and
decrease the amount of dissolved nutrients lost with water runoff,
whereas termites would increase nutrient leaching into runoff.