Abstract :
[en] Earthworms are known to play integral roles in soils, and are often referred to as vital soil and ecosystem engineers. They have the ability to influence a wide range of chemical, physical, and biological properties of soil environment. Therefore, it is important to understand how earthworm communities are impacted by tillage practices and exportation of crop residues. In the present study, earthworm and soil samples were collected from wheat cultivated fields in Gembloux, Belgium under four different agricultural practices: (1) conventional tillage with crop residues incorporated into the soil (CT/IN); (2) conventional tillage with crop residues exported from the field (CT/OUT); (3) reduced tillage with crop residues incorporated into the soil (RT/IN); and (4) reduced tillage with crop residues exported from the field (RT/OUT). The different agricultural practices were applied on luvisol soil for four consecutive years prior to the initiation of the current study. The purpose of this study was to research the influence of agricultural practices on earthworms with considering species and their interactions with soil properties.
The results indicated that the agricultural practices affected soil properties and earthworm communities.
The penetration resistance measured to a depth of 50 cm increased with increasing soil depth in all treatments. Soil compaction was significantly higher in RT compared with CT. For each depth, measures of soil physico-chemical properties showed significant differences among treatments. Furthermore, soil samples showed higher P and K concentrations in 0 – 10 cm soil depth compared with other depths. The main reason for the large K and P accumulation near the soil surface is the incorporation of crop residues.
Significant differences were not detected between residue incorporation depth treatments, where results showed mean earthworm abundance was respectively 182 and 180 individuals m-2 in CT and RT. Mean earthworm biomass was similarly not significantly different between CT and RT, where results were respectively 48.5 and 57.3 g.m-2. However, a significant difference was observed between IN and OUT treatments, suggesting the exportation of wheat residues will limit earthworm abundance and biomass, and will mask the effect of tillage. The endogeic species Apporectodea caliginosa strongly dominated the earthworm community (64%), whereas epigeic and anecic species remained < 3% and 5% of all earthworms in all agricultural practices. Findings indicate that endogeic and epi-anecic groups appears to be highly affected by tillage practice and the exportation of crop residues. The effect of exportation of crop residues appears more important than tillage intensity. The higher number of individuals found is associated with the greater disturbance.
In compacted soils, L. terrestris, L. castaneus and A. caliginosa species showed an increased abundance. The obtained results were attributable to earthworm activity and wheat residues, suggesting earthworms contributed to nutrient dynamics and soil structure, particularly at increased soil depths. Overall, the results emphasise the influence of exportation of crop residues on earthworm community and also, the important influence of earthworm activity on soil physico-chemical properties change, processes which are closely linked.
