Earthworm Lumbricus terrestris mediated redistribution of C and N into large macroaggregate-occluded soil fractions in fine-textured no-till soils

Abstract

By processing large quantities of crop residues, earthworms enhance the mineralization of organic matter but have also been shown to stabilize soil organic carbon (SOC) into soil fractions like microaggregates (53-250 µm) within macroaggregates (>250 µm) especially 2 in no-till soils. Our objective was to find direct evidence on the impact of an anecic, soil surface-feeding earthworm, Lumbricus terrestris L., on the redistribution of SOC and soil nitrogen (N) into macroaggregate-occluded soil fractions of boreal soils. We sampled soil (0-5 cm depth) from the middens of L. terrestris (mounds of collected residue and surface casts at the openings of its permanent burrows) and the adjacent non-midden (bulk) soil at three no-till sites in southern Finland: two clayey sites (sites 1-2) and one coarse textured site (site 3). Compared to bulk soil, the soil in L. terrestris middens featured general increase in aggregate size and content of SOC and N within the large macroaggregates (>2000 µm) at the clayey sites. The microaggregates within the large macroaggregates had accumulated more SOC and N in the midden soil especially at site 1 where 99% of the difference in total SOC between midden and bulk soil was associated with this type of SOC stabilization. At site 2, the increase in SOC found in the large macroaggregates was counteracted by a decrease in SOC in microaggregates within the small macroaggregates (250-2000 µm). No differences in SOC stored in soil fractions were found between midden and non-midden soil at the coarse soil site 3 with higher top soil decomposition rate compared to sites 1 and 2. Across the study sites, the total amount of SOC was 6% higher in midden soil compared to the bulk soil. These results suggest L. terrestris mediates the storage of SOC and N into better protected soil fractions in clay soils under boreal conditions.

Quality of soil from the nickel mining area of Southeast Sulawesi, Indonesia, engineered using earthworms (Pheretima sp.)

“…The study by Sheehy et al (2019) showed that the earthworm Lumbricusterrestris increased the potential for agricultural land to store C in macroaggregate -oculated microaggregates. The high organic C content in the soil that is disturbed by Pheretima sp's activity is thought to be related to the organic carbon content of microaggregate blankets formed through the activity of the worms in macroaggregates (biogenic), which could reach two times compared to macroaggregates without the worm's activity (Bottinelli et al, 2020).…”

Pedoclimatic factors and management determine soil organic carbon and aggregation in farmer fields at a regional scale

“…We also included several cropping practices variables, related to crop diversity, ley cultivation, tillage intensity, amount of organic inputs and nitrogen inputs. However, earthworm abundance and diversity were not assessed here, although it has been shown to be an important driver of soil aggregation (Fonte et al, 2007;Sheehy et al, 2019;Guhra et al, 2020).…”

Assessment of earthworm activity on Cu, Cd, Pb and Zn bioavailability in contaminated soils using biota to soil accumulation factor and DTPA extraction

“…Earthworms changed C and N transportation in soil (Hoang et al, 2016;Sheehy et al, 2019). Two-way ANOVA showed a significant influence of earthworm on C min (P < 0.01, Table 3), suggesting that earthworms affected soil C and N components by influencing soil microbial activities.…”

“…Two-way ANOVA showed a significant influence of earthworm on C min (P < 0.01, Table 3), suggesting that earthworms affected soil C and N components by influencing soil microbial activities. Earthworm intestinal microorganisms were associated with redistribution of C and N in soil (Sheehy et al, 2019). A. corticis could increase soil C mineralization through their promotion of soil respiration (Snyder et al, 2009).…”