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Phosphorus (P) is an important nutrient for plant growth. However, P is often poorly available for uptake by roots because it strongly adsorbs to the soil mineral phase. Recent research shows that earthworms can temporally and locally increase P availability to plants. However, the pathways through which they do so are not fully understood, and it remains unclear to what extent this capacity varies among earthworm species. Here we study the variation among earthworm species with respect to readily-available P in casts as well as other physico-chemical cast properties, in a greenhouse pot experiment using a soil with a low P status. The earthworms belong to eight commonly occurring earthworm species in the Netherlands: two epigeic species (a mixture of the compost earthworms Dendrobaena veneta/Eisenia fetida; Lumbricus rubellus); four endogeic species (Allolobophora chlorotica, Aporrectodea caliginosa, Aporrectodea rosea, Octolasion lacteum); and two anecic species (Aporrectodea longa; Lumbricus terrestris). For all species, the pH in water extracts of earthworm cast (pH = 7.4–8.2) was significantly higher (p < 0.001) than for the control bulk soil (pH = 6.6) and differed significantly (p = 0.003) among earthworm species. Similarly, the dissolved organic carbon (DOC) concentration in the same water extracts was an order of magnitude higher in earthworm cast compared to the control bulk soil and varied among species (p < 0.001). The size of the total pool of reversibly adsorbed P in earthworm cast was greater than in the control bulk soil, but no significant differences were found among earthworm species. Differences among species were present for the readily-available P pools extracted from casts, including P-Olsen and water-extractable ortho-P. Water-extractable ortho-P concentrations were much higher in the casts of all species as compared to the control bulk soil (0.9–6.8 vs 0.06 mg l−1 or to 9.0–68 vs 0.6 mg kg−1). Highest ortho-P levels were measured in L. rubellus casts and the lowest in casts of A. chlorotica. A positive correlation between the concentrations of DOC and ortho-P was observed (R2 = 0.72, p < 0.001). The observed variation in all measured physico-chemical cast properties could not be explained by conventional ecological earthworm classifications. Our results show that the nature and magnitude of earthworm-induced increased P availability differs dramatically among earthworm species. This strongly suggests that, apart from its size, species composition of the earthworm community is key to optimizing P availability to plants.

Given the well-known role of earthworms in the functioning and health of soils and whole ecosystems, feasible and reliable studies of their abundance and diversity in agricultural lands are essential for the effective design of best agricultural practices. However, previous work has shown that the extraction efficiency of different methods proposed seems to depend on species and size of earthworms and presumably on soil type, which makes creating an earthworm inventory difficult. In the present study, we compare the efficiency of five earthworm extraction methods combining hand-sorting with chemical expellants (hand-sorting, formalin, allyl isothiocyanate (AITC), formalin + hand-sorting and AITC + hand-sorting) over a wide range of soil properties (depth, texture and water regime) in cultivated and semi-natural habitats found in a Mediterranean region (CW-Spain). Sampling efficacy was measured in terms of number of earthworms extracted, taking into account different species, ecological groups, development stages, size of individuals, and soil properties. We found 20 species, only 6 endogeic and 1 anecic species being abundant. The anecic Aporrectodea trapezoides responded reasonably to chemical expellants, as did certain soil surface dwelling endogeic species (Microscolex phosphoreus and Microscolex dubius), with above 50% of specimens of these species sampled after chemical application. For other endogeic species, such as Allolobophora molleri and Aporrectodea rosea, chemical expellants gave poor results (

Aporrectodea rosea (Savigny, 1826) is a cosmopolitan earthworm widespread throughout the Holarctic. The available data on A. rosea genetic diversity (mainly from the Mediterranean region) suggests that this species can be divided into the Mediterranean and the Eurosiberian lineages. In this study we tested molecular variation within this species from the Northeastern Palearctic, namely from Russia, Belarus, and Kazakhstan, using nuclear and mitochondrial sequences. We detected previously unknown genetic diversity within the Eurosiberian lineage: basal representatives of this group from the south of Belarus were only distantly related to the rest of the lineage. This suggests that after the split of A. rosea into the Mediterranean and the Eurosiberian lineages, the latter diversified in eastern Europe with subsequent recolonization of the Mediterranean region. The paleogeographic history of this species is thus more complex than it was thought earlier. We found that A. rosea significantly increased its range over the last two decades, now being found in West Siberia; genetic diversity there is low compared to European Russia and Belarus. Compared to the closely related A. caliginosa, A. rosea had lower genetic diversity, probably caused by fewer dispersal events.

Eisenia nordenskioldi subsp. nordenskioldi (Eisen, 1879) is the most cold-tolerant earthworm species that is widespread in Northern Eurasia. We analyzed genetic variation among several geographically remote populations of E. n. nordenskioldi, as well as several other species of Lumbricidae, using mitochondrial (cox1) and nuclear ribosomal (ITS2) sequence markers. According to both markers, species of the genus Eisenia did not form a clade; in contrast, E. n. nordenskioldi and Eisenia nordenskioldi subsp. pallida grouped together with Siberian Aporrectodea rosea and Lumbricus rubellus on the phylogenetic tree built using combined cox1 + ITS2 data, suggesting that these species form an endemic Siberian clade. E. n. nordenskioldi turned out to be non-monophyletic and consisted of six highly diverged lineages having distinct distribution areas. Genetic variation within these lineages was also very high and geographically structured. Phylogeographic patterns within the lineages may suggest that their distributions was not affected by Pleistocene glaciations, and, therefore, may be a useful source of information for biogeographic reconstructions of Northern Eurasia.

Earthworms play a key role in soil ecology as they can reach high densities, are well known as soil engineers, and occupy a central position in soil food-webs. The identification of earthworms, however, is notoriously difficult and morphologically only possible for well-preserved adult specimens. Molecular markers could facilitate earthworm identification and would be a huge advantage in studies where it is important to species-specifically identify juveniles or where badly preserved specimens and remains of earthworms need to be identified. The aim of this study was to compare four mitochondrial genes (12S rRNA, 16S rRNA, COI, and COII) with respect to their value for identifying earthworms, calculating earthworm phylogenies, and discovering cryptic species. Our results indicate that all four genes are suitable for species identification. However, the genetic distances were approximately twice as high for the protein coding genes than for RNA coding ones. High genetic distances and deep genetic lineages, e.g. for Octolasion lacteum , Lumbricus rubellus and Aporrectodea rosea , indicate the possible presence of cryptic species and hamper molecular identification. The Bayesian analysis based on concatenated sequence data resulted in a phylogenetic tree with high posterior probabilities. The con-specific relationship of Aporrectodea spp. and Allolobophora spp. was not confirmed, underlining the ongoing discussion about the revision of these two genera. In conclusion, our findings suggest using 12S and 16S rRNA sequences as molecular markers for species identification whereas the COI gene is better suited to address genetic lineages and to explore possible cryptic species. Taxonomy and the identification of species are essential for most ecological studies. This study provides the needed molecular sequence information to develop molecular tools that can overcome many hurdles in studies on earthworms, their relationship and their ecology.

The response of earthworm communities to farming practices was assessed in 33 farms of the Soummam valley (Algeria). Market gardening was the most intensive practice with frequent tillage (94% farms), application of chemical (94%) and organic (70%) fertilizers and pesticides (70%). Orange tree plantations also received organic fertilization (42% of farms), NPK (95%), pesticides (71%) and tillage (95%) whereas in Olive plantations only 30% farmers used fertilizers and pesticide application was rare. Earthworm communities comprised 5 species: the ubiquitous Apporrectodea caliginosa , Aporrectodea rosea , Allolobophora chlorotica and Microscolex dubius and the native Octodrilus complanatus . Average density decreased from market farming areas (176 ± 27.6 ind m −2 ) to olive tree (149 ± 10.4 ind m −2 ) and orange tree plantations (73 ± 9.2 ind m −2 ). Biomass followed a slightly different order with a maximum of 44.0 ± 10.2 g fw m −2 in market farming areas followed by orange plantations (38.3 ± 8.0 g fw m −2 ) and olive plantations (35.6 ± 2.78 g fw m −2 ). Earthworm populations were comprised of 90% A. rosea and A. caliginosa . A. rosea favored market garden and olive systems while A. caliginosa did not show any clear preference. O. complanatus were abundant in market gardening sites with organic fertilizers whereas M. dubius was absent from orange tree plantations. Communities significantly covaried with farming practices and not with soil characteristics. In general, the density of all species was affected by intensification although the native species O. complanatus benefited from organic fertilization. Farming practices in the valley maintain rather high earthworm activities in spite of significant uses of chemical inputs. Further intensification might however affect these communities that showed clear sensitivity to all chemical inputs and tillage.

Dendrobaena mrazeki is an endemic earthworm species inhabiting dry habitats such as pine and thermophilous oak forests in Central Europe. Metabolically, D. mrazeki showed some features typical for endogeic species and some of epigeic ones. In comparison with the related Dendrobaena octaedra , D. mrazeki was a larger earthworm with fresh body mass of adult and subadult individuals of W = 0.59 ± 0.05 g. Its body mass-specific oxygen consumption ( M / W = 48 ± 5 μl O 2 g −1 h −1 , at 15 °C) was the lowest of all earthworms studied ( Aporrectodea caliginosa , Aporrectodea rosea , D. octaedra , Lumbricus castaneus , Lumbricus rubellus and Octolasion lacteum ), being strongly dependent on W ( b from the equation M / W = aW b about −0.8). D. mrazeki had low relative water content (77.4% of fresh body mass) and small relative amount of dry weight of the intestinal content (20.1% of dry body mass), which is similar to the epigeic D. octaedra . The respiration rate of D. mrazeki remained the lowest even after recalculating M / W to respiration rate per dry mass or per dry mass without the intestine content to correct for the differences among species in body water content and gut content.

The way soil is disrupted and deformed by earthworm movement is hard to quantify non-destructively. Two anecic earthworm species, Aporrectodea longa (Ude) and Lumbricus terrestris L., were compared in their effect on the soil around them as they burrow. Image analysis (particle image velocimetry, PIV) was used successfully to quantify the distance and direction of soil particle displacement by earthworm locomotion giving a unique insight into their effect on the soil structure development. The data collected from both species using PIV show a decline in soil displacement at increasing distance from the earthworm’s body. The quantity of soil being displaced was more to the sides of the earthworms (radially) than in front of the prostomium (axially). Also, L. terrestris displaced more soil than A. longa both axially and radially. The findings from this study suggest that PIV image analysis is a viable tool for examining soil displacement by earthworms and the method used has the potential to be applied to other soil organisms.

In laboratory experiments, earthworms are often observed to burrow through compacted soil layers, leading to the general assumption that these animals play a significant role in regenerating compacted soils in agricultural plots. To demonstrate this role under field conditions, the abundance of earthworm macropores inside compacted zones was estimated on plots under reduced (RT) or conventional tillage (CT). Then, different types of compacted zones typically found in CT (plough pan and compacted clods) and RT plots (compacted volume under wheel tracks) were experimentally simulated in wooden boxes, buried in the field and inoculated with different earthworm species. After 6 weeks of incubation, the number of macropores inside the compacted zones was examined. Field observations showed that approximately 10% and 30% of the compacted zones were colonised by at least one macropore in CT and RT plots, respectively. A significantly greater number of anecics was found in RT plots, but we could not conclude that this ecological type of earthworm plays a more major role in the regeneration process in these plots since there were fewer compacted zones and these covered a smaller area in CT. The semi-field experiment provided evidence that earthworm-mediated regeneration of compacted zones is possible and its nature varies between ecological types of earthworm. Lumbricus terrestris , which makes individual burrows that are vertical and deep, was the main species to cross through the plough pan. The other three earthworm species ( Aporrectodea giardi , A. caliginosa and A. rosea ) did burrow inside the other types of compacted zones (“wheel tracks” and “compacted clods”). In every case, however, macropore density was far greater in non-compacted zones, illustrating that avoidance of compacted soil by earthworms is important and should be taken into account when extrapolating results from laboratory studies.

Summary The soil seed bank functions to escape unfavourable environmental conditions and seed predation. Anecic earthworms are increasingly recognised as important dispersers and predators of plant seeds. In contrast, the role of the usually more abundant endogeic earthworms which live and feed in the soil on plant seeds is largely unknown. We tested whether (A) endogeic earthworms ( Aporrectodea rosea , Allolobophora chlorotica , Octolasion tyrtaeum , Aporrectodea caliginosa ) ingest and digest grassland plant seeds ( Phleum pratense , Bellis perennis , Trifolium repens , Poa trivialis , Plantago lanceolata , Medicago varia ), (B) the passage of seeds through the gut of endogeic earthworms modifies seed germination, and (C) excreta (mucus and casts) of endogeic earthworms modify seed germination. As a reference effects of the well-studied anecic species Lumbricus terrestris were determined. Endogeic earthworms ingested and digested all of the studied plant seeds; however, both ingestion and digestion were earthworm and plant species specific. Moreover, passage through the gut of endogeic earthworms and their excreta modified plant seed germination (gut passage: B. perennis ; excreta: Ph. pratense and Pl. lanceolata ). The results indicate that endogeic earthworms may strongly impact the composition of the soil seed bank and, consequently, plant community assembly via direct and indirect effects on plant seeds. Since post-dispersal seed predation is a key factor for the structure of plant communities, with the effect on seed survival potentially exceeding that of pre-dispersal predation, seed predation and changes in germination of seeds by endogeic earthworm species is likely to drive plant community composition.

A clear understanding of the size and structure of earthworm communities is important to sports turf facilities managers if they are to control the activity of earthworms within the soil. Earthworms are directly linked to a wide range of biogeochemical nutrient cycles, and are frequently described as ecosystem engineers. In this role they assist land managers in maintaining a healthy turf sward. Despite this, earthworm populations in sports turf were frequently suppressed using organochloride based vermicides prior to such compounds being banned in the UK. A survey of earthworm species diversity was carried out over 1 year, using mustard extraction at five golf courses in Bedfordshire and Buckinghamshire, UK, to investigate how species diversity varied temporally and was influenced by the physical environment within different course surfaces. Rank–abundance analysis indicated that four species of earthworm (Aporrectodea rosea, Lumbricus rubellus, Aporrectodea longa and Lumbricus terrestris) were more dominant in the community than any other. The endemic earthworm population number of the five study sites was found to differ significantly (p

Earthworm (Lumbricidae) populations were assessed in three replicated, field experiments with different management intensities conducted on grassland research farms on medium-textured mineral soils, located at Solohead (Co. Tipperary), Grange (Co. Meath) and Johnstown Castle (Co. Wexford), Ireland. The experiment at Solohead involved four levels of mineral fertilizer application (80, 175, 225 and 350 kg N ha−1), and the plots were rotationally grazed by dairy cows. Three levels of mineral fertilizer application were compared at Johnstown Castle (0, 225 and 390 kg N ha−1) and two at Grange (100 and 225 kg N ha−1), and the plots at these sites were rotationally grazed by suckler cows and followers or dry cattle. Between 10 and 15 earthworm species were recorded per site, with Allolobophora chlorotica and Aporrectodea caliginosa being dominant. Other abundant species included Aporrectodea rosea, Aporrectodea longa, Lumbricus terrestris, Lumbricus friendi, Lumbricus festivus, Lumbricus rubellus and Satchellius mammalis. Mean earthworm population densities per treatment ranged from 203 to 324 individuals m−2 and biomass from 60 to 176 g m−2. ANCOVA revealed significant overall positive relationships between management intensity (as indicated by N application rate) and earthworm abundance (F = 4.47, p

Specific composition of earthworm community has indicative value for evaluating the impact of agricultural practice on soil. The occurrence of species only like Aporrectodea caliginosa, Aporrectodea rosea, Lumbricus rubellus tolerant to disturbance is the result of intensive tillage and agricultural practice or the influence of strong limiting ecological factor. A community including more sensitive species Lumbricus terrestris and Aporrectodea longa, or the most sensitive species Allolobophora chlorotica and Lumbricus castaneus, indicates more favourable conditions of habitat.

Two endogeic earthworms, Aporrectodea rosea and A. trapezoides (Lumbricidae), occur in soils used for grain production in southern Australia. A glass-house experiment evaluated the influence of A. rosea and A. trapezoides on the release and availability of nitrogen (N) in a red–brown earth soil, which is very common in the region. This soil had been treated with sub-terranean clover or wheat residues (both either added to the soil surface or mixed through the soil at the start of the experiment), wheat residues incorporated into the soil 5 years earlier, or no residue amendment (control). The survival and biomass of earthworms varied with amendment. Most notably, the biomass of individual A. trapezoides was greater in the presence of sub-clover (probably better quality food) and when in mixed culture with A. rosea (effectively a reduction in the density of A. trapezoides ). A. trapezoides increased soil inorganic N in the presence of surface-applied sub-clover residues, but A. rosea did not. Incorporation of sub-clover residues further increased soil N in the presence of A. trapezoides , but not A. rosea . Wheat residues immobilised N when incorporated, but A. trapezoides reduced this immobilisation. A. rosea did not. No earthworm effects were detected in the control and old wheat residue treatments. The work suggests that A. trapezoides has the potential to significantly increase the availability of N in a soil commonly used for grain production across southern Australia.

Trace metals and metalloids (TMM) in forest soils and invasive earthworms were studied at 9 sites in northern New England, USA. Essential (Cu, Mo, Ni, Zn, Se) and toxic (As, Cd, Pb, Hg, U) TMM concentrations (mg kg −1 ) and pools (mg m −2 ) were quantified for organic horizons (forest floor), mineral soils and earthworm tissues. Essential TMM tissue concentrations were greatest for mineral soil-feeding earthworm Octolasion cyaneum . Toxic TMM tissue concentrations were highest for organic horizon-feeding earthworms Dendobaena octaedra , Aporrectodea rosea and Amynthas agrestis . Most earthworm species had attained tissue concentrations of Pb, Hg and Se potentially hazardous to predators. Bioaccumulation factors were Cd > Se > Hg > Zn > Pb > U > 1.0 > Cu > As > Mo > Ni. Only Cd, Se, Hg and Zn were considered strongly bioaccumulated by earthworms because their average bioaccumulation factors were significantly greater than 1.0. Differences in bioaccumulation did not appear to be caused by soil concentrations as earthworm TMM tissue concentrations were poorly correlated with TMM soil concentrations. Instead, TMM bioaccumulation appears to be species and site dependent. The invasive A. agrestis had the greatest tissue TMM pools, due to its large body mass and high abundance at our stands. We observed that TMM tissue pools in earthworms were comparable or exceeded organic horizon TMM pools; earthworm tissue pools of Cd were up 12 times greater than in the organic horizon. Thus, exotic earthworms may represent an unaccounted portion and flux of TMM in forests of the northeastern US. Our results highlight the importance of earthworms in TMM cycling in northern forests and warrant more research into their impact across the region.

International audience; Earthworm burrow systems are generally described based on postulated behaviours associated with the three ecological types. In this study, we used X-ray tomography to obtain 3D information on the burrowing behaviour of six very common anecic (Aporrectodea nocturna and Lumbricus terrestris) and endogeic (Aporrectodea rosea, Allolobophora chlorotica, Aporrectodea caliginosa, Aporrectodea icterica) earthworm species, introduced into repacked soil cores for 6 weeks. A simple water infiltration test, the Beerkan method, was also used to assess some functional properties of these burrow systems. Endogeic worms make larger burrow systems, which are more highly branched, less continuous and of smaller diameter, than those of anecic worms. Among the anecic species, L. terrestris burrow systems are shorter (9.2 vs 21.2 m) with a higher number (14.5 vs 23.5) of less branched burrows (12.2 vs 20.2 branches m(-1)), which are also wider (7.78 vs 5.16 mm) than those of A. nocturna. In comparison, the burrow systems made by endogeic species appeared similar to each other. However, A. rosea burrows were short and narrow, whereas A. icterica had a longer burrow system (15.7 m), more intense bioturbation intensity (refilled macropores or soil lateral compaction around them) and thus a greater number of burrows. Regarding water infiltration, anecic burrow systems were far more efficient due to open burrows linking the top and bottom of the cores. For endogeic species, we observed a linear relationship between burrow length and the water infiltration rate (R (2) = 0.49, p < 0.01). Overall, the three main characteristics significantly influencing water infiltration were burrow length, burrow number and bioturbation volume. This last characteristic highlighted the effect of burrow refilling by casts

Summary On four differently managed and abandoned alpine meadows and pastures densities, biomasses and 15 N signatures of the macrofauna were assessed to evaluate the structural and functional changes of the decomposer food webs. The composition of the macrofauna decomposer community changes remarkably after the abandonment of alpine meadows and pastures. Lumbricus rubellus functions as key primary decomposer on alpine meadows and pastures whereas on abandoned sites other primary decomposers including Dendrobaena octaedra , Cylindroiulus meinerti , C. fulviceps and diptera larvae become more important. Decomposer species, such as Enantiulus nanus, presumably function as both primary and secondary decomposers and endogeic earthworms, such as Octolasion lacteum and Aporrectodea rosea , uniformly function as secondary decomposers. Abandonment of pasturing causes a shift in the composition of the macrofauna and the newly established fauna is unable to process and translocate the litter materials produced by the plants of the abondoned sites.

Lead tolerance in individuals of the earthworm species Aporrectodea rosea collected from a clay pigeon shooting site was investigated. Lead concentrations in the shooting site soil and the un-shot control site were 6410±2250 and 296±98 mgPb kg−1 dry weight, respectively. Of these concentrations 1050±240 and 12±9 mgPb kg−1 dry weight were suggested to be available, using ammonium acetate (1 M), respectively. With respect to earthworm body burdens of lead the shooting site earthworms had a body burden of 6.1±1.2 mgPb g−1 dry weight while the uncontaminated site earthworms had almost a 1000-times lower body burden of 7.1±9.0 μgPb g−1 dry weight. Lead tolerance was assessed in uncontaminated soil that had been augmented with lead, using lead nitrate solutions, to obtain lead concentrations in soil of 0.5, 5 and 50 mgPb kg−1 dry weight. Earthworms were exposed for 28 days during which time a semi-qualitative assessment was made of their condition. Results showed no decrease in condition in the shooting site earthworms with increasing exposure time or concentration. In contrast, earthworms collected from an uncontaminated site showed a significant (p

Earthworm populations exhibit an irregular and aggregated distribution that may be related to vegetation, soil characteristics and biotic interactions. Their contribution to processes such as decomposition, soil aggregation and plant production is presumably limited to patches where earthworms are active. The spatial distribution of earthworm populations and how that distribution changes through time in temperate regions is not well known. This study mapped the spatial distribution of earthworm populations in 25 subplots of 50 m × 50 m sampling grids established in: (1) a cultivated corn field; (2) a mowed hayfield and (3) a deciduous forest in Quebec, Canada. Earthworms were collected three to four times a year using a combination of handsorting and formaldehyde extraction. Ten lumbricid species were found, the most common being Aporrectodea rosea Savigny. In 2001, we collected, on average, 46–177 earthworms m −2 in the corn field, from 138 to 224 earthworms m −2 in the hayfield and between 124 and 253 earthworms m −2 in the forest. Due to the spatial variation in earthworm distribution, at least 40 samples ha −1 are required to make an unbiased estimate of earthworm numbers and biomass. Five subplots (patches) from each site with the highest and lowest earthworm populations were re-sampled in 2002. Patches with high earthworm populations were generally distinguishable from those with low earthworm populations in the forest, but not in the agricultural sites; this may be due to greater heterogeneity in resource distribution in the forest than agricultural sites. Further work on earthworm spatial and temporal distribution is required to determine the scale at which earthworm induced changes in soil processes and plant production may be detected.

Earthworms Allolobophora chlorotica and Aporrectodea longa were inoculated into Calvert landfill site in spring 1992, in conjunction with the planting of two tree species Alnus glutinosa and Acer pseudoplatanus. Monitoring has taken place over a period of 11 years. Sampling in 2003 revealed that earthworm distribution no longer equated to the inoculation treatments; the worms had spread extensively. The presence of A. glutinosa had a significant effect (p

Summary A mixed stand of red oak (Quercus rubra) and common beech (Fagus sylvatica) on a compacted and acidified sandy loam soil was harvested and reforested with ash (Fraxinus excelsior) in 1992. The ecosystem restoration trial in this newly established ash plantation included 180 trees and was set up in a block design with 4 blocks, 3 experimental groups per block and 15 trees per experimental group. Experimental groups were: (1) application of P, K, Ca and Mg fertiliser to the planting pit; (2) combined application of fertiliser and earthworms to the planting pit; and (3) a control without additional restoration measures. Fertiliser application consisted of 500g dolomite, 100g Thomas slags and 100g kieserite; earthworm introduction consisted of 40 individuals, being 20 anecics (Lumbricus terrestris L. and Nicodrilus longus Ude) and 20 endogeics (Aporrectodea caliginosa Sav., Aporrectodea rosea Sav. and Allolobophora limicola Michaelsen). Tree growth was monitored annually. The control trees failed to grow and died after two years. Excellent growth was found for treated trees, and treatment-related growth patterns were observed: fertilised trees grew faster than fertilised trees with earthworms during the first two years, with the trend reversed from year 4 onwards. Although this trend suggested that introduced earthworms provided a more sustained response to fertiliser, this was not conclusively confirmed by an evaluation of 24 trees 10 years after planting (based on nutrient concentration in above-ground biomass and soil, litter biomass, earthworm biomass, and aggregate stability of organic particles in the soil); although statistically significant differences were found between treated and untreated plots, differences between fertilised plots with and without earthworms were not significant. Endogeic earthworms recolonised most fertilised plots, with or without earthworm introduction. Anecic earthworms did not colonize any plots. Although our findings suggest that earthworm introduction might contribute to a sustained fertiliser response in ash trees, more experiments are needed to demonstrate the precise role of earthworm introduction as part of integrated forest soil restoration.

A mixed stand of red oak (Quercus rubra) and common beech (Fagus sylvatica) on a compacted and acidified sandy loam soil was harvested and reforested with ash (Fraxinus excelsior in 1992. The ecosystem restoration trial in this newly established ash plantation included 180 trees and was set up in a block design with 4 blocks, 3 experimental groups per block and 15 trees per experimental group. Experimental groups were: (1) application of P, K, Ca and Mg fertiliser to the planting pit; (2) combined application of fertiliser and earthworms to the planting pit; and (3) a control without additional restoration measures. Fertiliser application consisted of 500 g dolomite, 100g Thomas slags and 100g kieserite; earthworm introduction consisted of 40 individuals, being 20 anecics (Lumbricus terrestris L. and Nicodrilus longus Ude) and 20 endogeics (Aporrectodea caliginosa Sav., Aporrectodea rosea Sav. and Allolobophora limicola Michaelsen). Tree growth was monitored annually. The control trees failed to grow and died after two years. Excellent growth was found for treated trees, and treatment-related growth patterns were observed: fertilised trees grew faster than fertilised trees with earthworms during the first two years, with the trend reversed from year 4 onwards. Although this trend suggested that introduced earthworms provided a more sustained response to fertiliser, this was not conclusively confirmed by an evaluation of 24 trees 10 years after planting (based on nutrient concentration in above-ground biomass and soil, litter biomass, earthworm biomass, and aggregate stability of organic particles in the soil); although statistically significant differences were found between treated and untreated plots, differences between fertilised plots with and without earthworms were not significant. Endogeic earthworms recolonised most fertilised plots, with or without earthworm introduction. Anecic earthworms did not colonize any plots. Although our findings suggest that earthworm introduction might contribute to a sustained fertiliser response in ash trees, more experiments are needed to demonstrate the precise role of earthworm introduction as part of integrated forest soil restoration.

The earthworms, Aporrectodea rosea and A. trapezoides (Lumbricidae), occur commonly in soils used for grain production in south-eastern Australia, but their distributions are patchy and their abundance low. In a field experiment, inoculations of A. trapezoides, but not A. rosea, increased the growth of oats at early tillering and oat straw and grain yield at harvest. Neither earthworm species influenced the growth and yield of lupins. At early tillering of the oats and concurrent flowering of the lupins, the amounts of 1 5 N (from fertiliser applied the year before) taken up by both oats and lupins were greater in the presence of A. trapezoides, but not A. rosea. However, there were no differences in the % N in lupin and oat plants between the earthworm treatments. At harvest, there were no differences in the amounts of 1 5 N taken up by the lupin straw, nor were there in the % N in straw or grain for either lupins or oats between earthworm treatments. The 1 5 N contents of the oat straw and the lupin and oat grain were higher in the presence of both earthworm species when compared with controls. More than 90 % of the N in the lupins was fixed symbiotically. The proportion of fixed N was reduced slightly by A. trapezoides. Inorganic N was analysed at various depths in the soil profile at sowing and early tillering and flowering. An earthworm effect on soil inorganic N was recorded in only one instance - at early tillering / flowering, when soil inorganic N was slightly higher at 0.6-1 m depth in the presence of A. trapezoides. Management practices, which improve earthworm abundance, in particular that of A. trapezoides, in cropping soils in southern Australia may enhance productivity of some, but not all, crops.

Earthworms are recognized to increase soil porosity, reorganize soil structure, and stimulate soil microflora and nutrient mineralization. The properties of earthworm casts should depend both on earthworm species or ecological group and on soil properties. Interactions between earthworm species and soil types have been suggested, but only poorly demonstrated. In order to better understand those interactions, two hypotheses led our study: (1) Soil type has a greater influence on cast properties than earthworm; (2) Earthworms from different species influence cast properties differently; (3) The intensity and direction of the impact of each earthworm species on cast properties vary with soil properties. Fifteen physical and chemical variables (N–NH 4 + , N–NO 3 − , total organic C and N, C/N ratio, CaCO 3 , pH, P, K + , Mg 2+ , Mn 2+ , Na + , CEC, moisture, wettability) were measured in casts of three earthworm species ( Lumbricus terrestris , Allolobophora chlorotica and Aporrectodea rosea ) produced in three temperate soils. Univariate and multivariate analyses showed that earthworm species and soil types significantly impacted cast properties. pH, N t , K and Mg contents were interactively altered by both factors. Multivariate analysis showed that a difference of soil type had a major impact on casts properties (62%) compared to the impact of a difference of earthworm species (10%). Cast properties were most impacted by L . terrestris , then by A . chlorotica and last by A . rosea . The response ratio (ratio of the properties of the casts to the properties of the bulk soil) was used to quantify the effect of earthworm species compared to the control soil. It showed a higher response of variables in casts in nutrient-rich soils, especially in casts of L . terrestris . The interactions between earthworm species and soil types on cast properties were discussed with regards to earthworm ecology, properties of the soil, and earthworm modifications of cast microflora.

The aim of this study was to characterize the spatial distribution of earthworm species assemblages on a chalky slope of the Seine Valley (Upper Normandy, France), with contrasting vegetation cover representing the different stages of a typical post-pastoral secondary succession. Samples were hand sorted in a spatially explicit design consisting of a regular grid. A Principal Component Analysis was performed to identify species associations. Maps of the factorial coordinates of sample points together with geostatistical analysis were used to describe the spatial structure of the assemblages. The first axis of the PCA opposed points with high density to others with low. The resulting spatial structure was significant. The second axis opposed points where species assemblages were dominated either by an endogeic (Allolobophora chlorotica), an anecic (Aporrectodea longa) and an epigeic species (Lumbricus castaneus) to others dominated by two endogeics (Aporrectodea rosea and Octolasium cyaneum). A significant spatial structure was detected, with alternating patches characterised by one species assemblage or the other. The location of these structures did not seem to be clearly associated with a specific vegetation type. These results revealed a complex determinism of species co-occurrence at small spatial scale.

The aim of this study was to measure the pressures exerted by earthworms during burrowing. For this purpose we developed two methods with which to quantify the axial and radial pressure. The data were recorded with an electronic balance that was connected to a PC. Artificial earthworm burrows were used to standardize the measurements. Plexiglas tubes with diameters ranging from 2 to 6.3 mm which corresponded to the diameter of the earthworms were used. A pin was placed inside the tubes, on which the earthworms exerted a pressure by peristaltic locomotion. Only the maximum values of the pressure measurement were taken into account for evaluation, and the arithmetic mean was calculated. The measurements were conducted with Aporrectodea longa, Lumbricus terrestris, Aporrectodea caliginosa, Octolasion cyaneum, Allolobophora chlorotica, Aporrectodea rosea, Lumbricus rubellus and Dendrobaena octaedra. The species examined were classified into ecological groups. The mean axial pressures exerted by each group were in the order: epigeic (14–25 kPa), endogeic (27–39 kPa) and anecic (46–65 kPa). For the mean radial pressure the order was: epigeic (39–63 kPa), anecic (72–93 kPa) and endogeic (59–195 kPa). It was apparent from the results that radial pressure is the most important pressure with respect to the burrowing activity of earthworms.

I describe a method to study the reproductive rate of earthworms in the field. The method is based on a detailed knowledge of the influence of temperature on the development of earthworm cocoons. This relationship [ R ( T )] was described for populations of Aporrectodea longa and A. rosea that were studied in a field experiment from 1 May to 6 June, 1997. Soil temperature was measured throughout the study and on 6 June the density of cocoons was estimated. The sampled cocoons were incubated in the laboratory and their hatching distribution was recorded. Based on R ( T ), the average development time in the field of cocoons produced on 1 May was predicted, and the hatched cocoons could thus be scored as either produced during the study, or before. This made it possible to estimate the density of cocoons produced during the study. The density of adults was also estimated by soil sampling during the study, and finally the reproductive rate could be calculated as density of cocoons divided by density of adults. Using this method the reproductive rate (viable cocoons) of A. longa was estimated to 0.09±0.04 cocoon adult −1 d −1 (mean±S.D., n =4), corresponding to a cocoon production throughout the study of 3.3±1.6 adult −1 . The reproductive rate of A. rosea was estimated to 0.20±0.06 cocoon adult −1 d −1 , corresponding to 7.2±2.1 adult −1 . The average soil temperature was 10°C. These results confirm results of previous studies indicating that the reproductive rate of A. longa is low in comparison with other earthworm species. On the other hand, the results suggest that the reproductive rate of A. rosea under natural conditions may be much higher than assumed.

Studies of earthworm species and their activity, expressed as channels, on cultivated loamy (Humic Cryaquept) and clayey soils (Typic Endoaqualf and Typic Cryaquept) were conducted in southern and central Norway before conversion from conventional to organic cropping systems. At all the three study areas: Landvik (Grimstad), Voll (As) and Kvithamar (Stjordal), the earthworm species Aporrectodea caliginosa, Aporrectodea rosea, Allolobophora chlorotica and Lumbricus rubellus were found. At Landvik, where the deep-burrowing species Aporrectodea longa, A. caliginosa and Lumbricus terrestris dominated, medium (4–6 mm) and coarse (>6 mm) earthworm channels were most numerous below the plough layer. Almost no coarse pores were found at Voll and Kvithamar. The volume of earthworm channels below the plough layer was 0.6–0.8% of total soil volume at Landvik and Voll and 0.3–0.4% at Kvithamar. Earthworm channels >6 mm below the plough layer were useful to identify present and previous activity of deep-burrowing earthworms such as L. terrestris. Below the plough layer, roots were almost entirely restricted to earthworm channels and interaggregate spaces.

In a greenhouse study, the ability of two earthworm species (Aporrectodea trapezoides and Aporrectodea rosea) to alter the rate of growth of wheat, barley and faba beans in three soils of contrasting texture (sandy loam, loam and clay) was examined. Three experiments are reported. In experiment 1, A. trapezoides (1, 3 or 6 per pot of 1 kg soil) in the sandy loan was associated with a significant increase in the growth (31%) of wheat seedlings at 7 weeks old, but had no significant effect in the loam or clay soils. The presence of earthworms was associated with increased foliar N concentrations (10–20%) and water-use efficiency (4–17%) in all three soil types. In experiment 2, there were no significant effects of A. trapezoides or A. rosea (10 per pot of 4 kg soil) on the dry weight of faba beans at 10 weeks old, except for A. rosea in the loam soil which reduced the total dry weight by 17%. In experiment 3, both A. trapezoides and a. rosea (10 per pot of 4 kg soil) caused a significant increase in the dry weight of barley plants (60%), root growth (40% and 30%, respectively) the number of tillers (50% and 35%, respectively) and grain yields (50% and 45%, respectively) in the sandy loam soil but had no effect on these measures in the loam soil. In the clay soil the presence of both earthworm species was associated with a substantially reduced plant dry weight (40% and 20%, respectively), tiller number (20%) and grain yield (40% and 20%, respectively). A further treatment (NPK fertiliser applied at a rate commonly used in the field) produced no increase in growth of faba beans or wheat. Effects on soil hardness and bulk density varied with soil type and earthworm species. We conclude that the response of plants to earthworm activity varied with soil type and plant species.

The influence of the earthworms Aporrectodea trapezoides and A. rosea on subterranean clover and perennial ryegrass, grown in a red-brown earth soil artificially infested with R. solani , was examined. In soil artifically infested with R. solani on wheat chaff, the presence of A. trapezoides (at a number equivalent to 300 m −2 ) was associated with a significant reduction in the percentage length of roots containing Rhizoctonia lesions and a significant increase in shoot weight, root weight and root length of both subterranean clover and perennial ryegrass. The presence of A. rosea , at a number equivalent to 300 m −2 , was associated with a significant increase in the shoot weight and root length of subterranean clover, but A.rosea did not significantly influence the percentage root length containing Rhizoctonia lesions on either subterranean clover or perennial ryegrass. In the absence of R. solani inoculum, neither A. trapezoides or A. rosea influenced shoot weight, root weight or root length of subterranean clover. However, both earthworms significantly increased the shoot weight of perennial ryegrass in the absence of R. solani inoculum. These results demonstrate the potential of A. trapezoides and A. rosea to reduce the deleterious effect of R. solani on specific pasture plants.

Field surveys have shown that the introduced lumbricid earthworm, Aporrectodea rosea, predominates in fields used for cereal-pasture rotations in South Australia and western Victoria. Another introduced lumbricid, A. trapezoides, also occurs in these fields, but is usually much rarer. A glasshouse experiment investigated the influences of A. rosea and A. trapezoides on wheat and subterranean clover production. The plants were grown in a red-brown earth (Palexeralf), maintained at 60% field moisture capacity with the equivalent of 460 worms m−2. Wheat was grown first and then the soil was re-used for the clover. A. trapezoides increased wheat plant biomass by 39%, grain yield by 35%, grain N content by 14% and straw N content by 19% compared with controls (no worms). A. rosea increased wheat plant biomass by 13%, but had no significant influence on grain yield or grain or straw N content. The biomass of clover herbage was increased by 21% by A. trapezoides, but A. rosea had no effect. Neither earthworm species influenced the N content of the clover or the dry weight of clover roots. The implications of these results for future management of earthworms in cereal-pasture ratations are discussed.

Crop-monitoring by farmer groups has been established to identify agronomic and soil factors limiting crop yields and to promote the adoption of sustainable farming practices in South Australia. The use of earthworms as a potential indicator of sustainability has been investigated with a survey of 95 paddocks sown to wheat, barley or peas, within an area of about 3500 km 2 . Mean annual rainfall ranged from less than 350 mm to more than 500 mm, and soils varied from coarse sands through lighter loams to heavy clays. The dryland cropping soils in South Australia have been colonized by four immigrant earthworm species, Aporrectodea rosea (Savigny), Aporrectodea trapezoides (Duges), Microscolex dubius (Fletcher) and Microscolex phosphoreus (Duges); populations are generally dominated by A. rosea . Population differences, such as the higher numbers of A. rosea recorded under barley than peas and more juveniles under peas than wheat, and the occasional abundance of other species in some paddocks may be used to indicate changes in soil conditions associated with management. Conservation tillage, retaining plant-residues and reducing cultivation, is being promoted as desirable in developing sustainable farming systems and the inverse relationship between earthworm abundance and intensity of tillage (r = −0.69 ∗∗∗ ) provides support for earthworms as a potential indicator of sustainability. Earthworm abundance showed a small but significant correlation between earthworm activity and grain yields (r = 0.44 ∗∗∗ ) and grain protein content (r = 0.52 ∗∗∗ ). A positive correlation between nitrogen fertilizer levels and earthworm numbers (r = 0.48 ∗∗∗ ) and biomass (r = 0.43 ∗∗∗ ) may be related to increased soil organic matter, derived from increased plant growth. The distribution and abundance of earthworms is dependent not only on management related to crop production, but also on local soil and climatic factors. Density and biomass were significantly higher in paddocks with higher annual rainfall and inversely correlated with levels of coarse sand. The soils, crops, climate, management and history of a region of the geographic scale surveyed here is probably too diverse to provide simple relationships between earthworms and plant productivity. It is important to distinguish the broad concept of sustainable productivity on a regional basis from the reality of productivity and sustainability on the spatial and temporal scales of activity of the organisms studied and the production and management processes involved. At an appropriate scale, ecological data on both the species composition and on functional groups within earthworm communities, may be useful indicators of crop production and its sustainability.

The effects of metal contaminants on the population density and species composition of earthworms were studied at 22 sites around a primary smelting works situated at Avonmouth, southwest England. All worms were absent from six sites within 1 km of the factory and numbers were also reduced significantly at an additional four sites 2 km from the plant. Total earthworm density was found to be inversely related to concentrations of metals in soils. some species of earthworms were found to be more ‘sensitive’ to metals and were absent from sites where more ‘tolerant’ species persisted. For example, Lumbricus rubellus, Lumbricus castaneus and Lumbricus terrestris were all present at sites close to the smelter where Aporrectodea rosea, Aporrectodea caliginosa and Allolobophora chlorotica were absent. The first three ‘tolerant’ species have more active calcium secretion glands in their gut than the three ‘sensitive’ worms. Calcium is known to be involved in the sequestration and elimination of various metals through the chlorogogenous tissue. Toxicity tests were carried out with a ‘sensitive’ and a ‘non-sensitive’ earthworm species ( Lumbricus rubellus and Aporrectodea rosea respectively) to examine if earthworm species distribution could be related to their susceptibility to the metals. In addition, the OECD recommended species Eisenia fetida was tested, to compare the sensitivity of this worm to the two commonly occurring soil species. Zinc was the metal used for these tests, since earlier comparisons of metal toxicity between the laboratory and field have shown that of the four metals released from the smelting works (Cd, Cu, Pb, Zn), it is zinc that is limiting the distribution of worms. Test results indicated that Aporrectodea rosea is more sensitive to the effects of zinc than Lumbricus rubellus . Thus, it appears that differences in the distribution of species of earthworms around the smelter can be related to variation in sensitivity to zinc. Both species were affected by zinc at lower concentrations than Eisenia fetida .

In a field trial in a red-brown earth, the interaction between the earthworms Aporrectodea trapezoides and A. rosea (added at an equivalent density of 100 or 300 m −2 ) and wheat grain yield was examined, both in the presence or absence of inoculum of Rhizoctonia solani or the take-all fungus Gaeumannomyces graminis var. tritici (Ggt) . In the absence of R. solani or Ggt inoculum, neither earthworm significantly influenced plant top weight 71 days after sowing. However at harvest, A. trapezoides at an equivalent density of 100 or 300 m −2 significantly increased grain yield (by 56% and 82%, respectively) and plant top weight (by 53% and 76%, respectively). A. rosea at these densities did not significantly influence plant top weight or grain yield. In soil artificially infested with Rhizoctonia solani , there was a significant increase from 0.06 to 1.05 in the Rhizoctonia root disease rating 71 days after sowing, but R. solani inoculum did not significantly influence plant top weight or grain yield at harvest. A. trapezoides and A. rosea did not significantly influence the Rhizoctonia root disease rating and A. trapezoides (at an equivalent density of 300 m −2 ) was associated with a significant increase in grain yield at harvest. In soil artificially infested with Ggt , there was a significant increase from 0.2 to 94% in the length of seminal roots containing take-all lesions 71 days after sowing and plant top weight and grain yield were significantly reduced by Ggt inoculum at harvest. When the effects of the different densities of each earthworm species across all the Ggt treatments were averaged, both A. trapezoides and A. rosea (at an equivalent density of 100 or 300 m −2 ) significantly reduced the Ggt root disease rating. In the presence of Ggt inoculum, A. trapezoides and A. rosea (at an equivalent density of 300 m −2 ) were associated with a significant increase in plant top weight at harvest, but neither earthworm significantly influenced final grain yield. These results demonstrate the potential of A. trapezoides to increase wheat grain yield in the field and that this ability may be influenced by the presence of R. solani and Ggt .

The effects of previous cropping history (varying periods of pasture or arable management) on soil organic C and microbial biomass C content and on the size and composition of earthworm populations were investigated on a range of mixed cropping (arable in rotation with pasture) farms. Some 105 fields located at 24 different commercial farms across the Canterbury Plains of New Zealand were sampled during spring. No native megascolecid earthworms were recorded. Up to five introduced European species were identified at sample sites. Overall, about 80% of earthworms were Aporrectodea caliginosa ,10% were Aporrectodea trapezoides and 5% were Lumbricus rubellus . The remaining 5% were Octolasion cyaneum and Aporrectodea rosea . All five species were found under long-term pasture. As the length of time under arable production increased, the number of species declined until, under continuous arable production, only A. caliginosa and A. trapezoides were recovered. Although soil organic C content was not greatly affected by cropping history, microbial biomass C content generally increased with time under pasture and decreased with time under arable. Earthworm numbers and biomass showed a similar but more pronounced trend to that of microbial biomass. This trend is reflected in the increased organic matter inputs under pasture and decreased inputs and increased decomposition under arable. In mixed cropping rotations, earthworm populations varied greatly with cropping history. Populations reached their maximum (over 800 m −2 ) after about 3 years under pasture whilst with more than 3 years under arable they were less than 400 m −2 . With continuous arable production for more than 9 years, populations fell to below 100 m −2 . Similar trends were found for earthworm biomass.

An understanding of the effects of ploughing on earthworm dynamics is required for the design of organic cropping systems maximising the beneficial effects of earthworms. Earthworms are often reported to be disturbed by ploughing, which is frequently used for weed control in organic farming. In this preliminary study, we investigated the effect of ploughing on the dynamics of two common endogeic species: Aporrectodea caliginosa and Aporrectodea rosea, to test the assumption that the sensivity to ploughing is species dependant. Two field trials were set up in October 2009 and November 2010, at two locations on a haplic luvisol, located in northern France. For comparison, part of each field was left unploughed, with the rest being ploughed. Earthworms were sampled at ten dates between October 2009 and July 2010 at Vi and six dates between November 2010 and March 2011 at Fa. Seven species were found in these two fields, with more than 88% of the earthworms belonging to two endogeic species, A. caliginosa and A. rosea. Ploughing had contrasting effects on the two species. A. caliginosa was more sensitive than A. rosea to tillage. In the unploughed part of the field, in 2009, the population remained small (less than 100 individuals m(-2)) and it was assumed that the two species were in competition for food. In 2010, the carrying capacity was higher, and A. caliginosa abundance reached 300 individuals m(-2), whereas the abundance of A. rosea remained below 90 individuals m(-2). In 2009, the effect of ploughing on A. caliginosa was immediate and persisted throughout the experiment, from October 2009 to June 2010, with an 80% decrease in abundance in June 2010. In 2010, the effect was delayed, but populations decreased during the winter following ploughing, with a 60% decrease in January 2011. Concerning A. rosea, the differences between the ploughed and the unploughed treatments were lower than for A. caliginosa. Our results confirm that endogeics earthworms may adapt themselves to the disturbance caused by tillage. Our observations suggest that A. caliginosa is more sensitive to ploughing than previously reported. These preliminary findings were obtained under favourable climatic conditions. They may help to define the optimal scheduling of tillage for earthworm conservation. (C) 2012 Elsevier B.V. All rights reserved.

A study demonstrated the ability of the earthworms Aporrectodea rosea and Aporrectodea trapezoides (added at an equivalent density of 100 or 300 m −2 ) to reduce the disease severity of Rhizoctonia soiani Kuhn on wheat in the field. In a calcareous sandy loam artificially infested with R. solani , the addition of these earthworms caused a significant ( P = 0.02) reduction of the Rhizoctonia root disease rating and had a significant ( P = 0.01) positive effect on shoot weight. Neither earthworm number or earthworm species had a significant ( P R. solani , neither the presence of these earthworms, earthworm species nor earthworm number influenced root disease rating. However, under these conditions the addition of earthworms ( P = 0.01) had a significant positive effect upon shoot weight. To our knowledge these results demonstrate for the first time, the potential of earthworms to contribute to the disease suppression of a cropping soil in a field situation.

The influence of the earthworms A. rosea and A. trapezoides on wheat plants, grown in soil artificially infested with the take-all fungus Gaeumannomyces graminis var. tritici (Ggt) was examined. In pot trials, using a red-brown earth soil artificially infested with Ggt , the presence of the earthworm A. trapezoides (at a density equivalent to 314 or 471 m −2 ) was associated with a significant ( P Ggt , shoot weight was not significantly ( P > 0.05) influenced by the presence of A. trapezoides .Two field trials were conducted, in which A. rosea and A. trapezoides were added, at an equivalent density of 100 or 300 m −2 , to cylinders driven into the soil. In a calcareous sandy loam artificially infested with Ggt , the presence of the earthworms A. rosea or A. trapezoides (at these densities) was associated with a significant ( P A. rosea or A. trapezoides (at an equivalent density of 300 m −2 ) caused a significant increase in shoot weight. In contrast, in the absence of added Ggt , shoot weight was not significantly ( P >0.05) influenced by the presence of A. rosea or A. trapezoides . In a second field trial in a red-brown earth, the presence of the earthworm A. trapezoides (at an equivalent density of 300 m −2 ) was associated with a significant ( P A. rosea or A. trapezoides did not cause a significant increase in shoot weight. In the absence of Ggt , shoot weight was not significantly ( P >.05) influenced by the presence of A. rosea or A. trapezoides .These results demonstrate the potential of the earthworms A. rosea and A. trapezoides , under both greenhouse and field conditions, to reduce the severity of take-all disease on wheat.

In a greenhouse study, the ability of the earthworms Aporrectodea rosea and A. trapezoides to influence the foliar concentration of elements and the growth of wheat plants was assessed 27 days after sowing in a sandy loam soil. The presence of A. rosea and A. trapezoides (at densities equivalent to 314 and 471 m-2, respectively) caused a significant increase in the shoot dry weight of wheat. The presence of A. rosea and A. trapezoides (at densities equivalent to 314 and 157 m-2, respectively) was also associated with a significant increase in the root dry weight of wheat. The presence of A. rosea caused a significant increase in the foliar concentration of Ca, Cu, K, Mn, N, Na, and P, but did not influence the foliar concentration of Al, B, Fe, Mo, Mg, S, and Zn. The presence of A. trapezoides was associated with a significant increase in the foliar concentration of Al, Ca, Fe, K, Mn, N, and Na, but did not influence the foliar concentration of B, Cu, Mo, Mg, P, S, and Zn. These results demonstrate the potential of A. rosea and A. trapezoides to increase the growth of wheat in a sandy loam soil and suggest that the mechanism by which they increased plant growth was, in part, through increasing the availability and uptake of nutrients from this soil.

The capacity of earthworms and soil microorganisms to influence plant growth is well known. However, the interactions between them have been little studied. Recent work in southern Australia has examined these associations with a view to managing both earthworms and beneficial microorganisms to promote cereal and pasture productivity. In this paper we examine the role of earthworms as vectors of beneficial soil bacteria and their capacity to influence the population dynamics and impact of microorganisms on soil and plants. The earthworms Aporrectodea trapezoides and Aporrectodea rosea are the most common species in agricultural ecosystems in southern Australia. They have been shown to spread Pseudomonas corrugata 2140R, a biocontrol agent for Take-all (a fungal disease of wheat roots caused by Gaeumannomyces graminis var. tritici ) through soil with corresponding colonization of the roots of wheat seedlings at soil depths of 3–9 cm. In addition, A. trapezoides can spread Rhizobium through the soil and cause increased root colonization and nodulation of legume roots. Despite evidence that populations of soil microorganisms are affected by earthworm activity at a small spatial scale (e.g. in casts or tunnel walls), there is little evidence to demonstrate that earthworms affect populations at larger spatial scales. Take-all and Rhizoctonia bare patch are the most serious fungal root diseases of wheat in southern Australia. Laboratory trials have shown that, in the presence of the worms A. trapezoides and A. rosea , symptoms of these diseases in wheat seedlings are substantially reduced. In a further trial, the presence of A. trapezoides was associated with a 100-fold decrease in population size of Rhizobium recoverable from soil after 40 days.

The morphology of surface-opening burrows made by earthworms in a South Australian duplex Red-brown Earth was investigated. Coordinate points along burrows were measured during careful excavation. Burrow length, orientation and the frequency of branching were measured. Mean burrow length was 398 mm (s.d.=189) with typically 2 to 3 branching points. Polar coordinate representation of the burrows showed them to be nearer to vertical at greater depths. Maximum depth of excavated burrows was approximately 250 mm, placing them almost entirely in the soil A horizon.

In a submontane beechwood on limestone near Gottingen (Germany), gut contents of adult earthworms were analysed. Paniculate detritus, non-particulate detritus, and mineral components were differentiated by sieving and ashing; plant remains were bleached and identified microscopically. Lumbricus terrestris (the only anecic species in the study area) was the only earthworm with high amounts of particulate plant remains in the gut (median 38% dry wt). Preferential feeding on non-beech litter could be demonstrated. Median total organic gut content was 76% dry wt. L. castaneus (the dominant epigeic species) had a high proportion of organic gut contents (median 61% dry wt) which was mainly non-particulate detritus. The endogeic species (Aporrectodea caliginosa, Aporrectodea rosea, Octolasion lacteum, O. cyaneum) had no, or only few particles in the gut. Median organic fractions were 39, 40, 44, and 29% dry wt, respectively. It is concluded that endogeic earthworms preferentially feed on soil compartments with high detritus concentrations, as average soil organic matter contents were ⩽20% dry wt.

Earthworms were surveyed in 113 pasture soils in the Mount Lofty Ranges, Fleurieu Peninsula, South Australia, in a region where annual rainfall is 600–1200 mm and the climate is mediterranean. The soils within these pastures included a variety of profile forms (e.g. sandy soils with yellow, brown or red clays in the B horizon; uniform coarse textured sands). The most widespread earthworm species were Aporrectodea trapezoides (found at 95% of sites), Microscolex dubius (61%), Aporrectodea rosea (38%) and Aporrectodea caliginosa (36%). These are all introduced species. The total densities of earthworms varied from 0 to 608 m −2 (mean = 169.2). At most sites (66%), densities were −2 . Native earthworms were present at 40 sites but their total densities exceeded 100 m −2 at only 7 sites. The species richness and diversity of the earthworm communities were low; never more than 5 species were found in any one pasture (mean = 3.1). The abundance of the introduced species (all species combined) varied between soil profile forms, being least in the uniform sands. No such variation was found for native species. Several significant, but weak, correlations were obtained between the numbers and weights of earthworms and other environmental variables (e.g. rainfall, depth of A horizon, % sand, clay. nitrogen and carbon). Stepwise multiple regression of the numbers and weights of introduced species against these environmental variables suggested that % clay was the most important regressor. The potential for increasing the abundance and diversity of earthworms in Australian soils is discussed.

Earthworms have the ability to alleviate many soil degradational problems in Australia. An attempt to optimize this resource requires fundamental understanding of earthworm ecology. This study reports the seasonal changes in earthworm populations in the Midlands of Tasmania (

The radial pressures generated by the earthworm Aporrectodea rosea were measured in a study of the conditions under which the worms were able to crack soil discs into which they were encouraged to tunnel. The tensile strength of replicate discs was determined by indirect tension tests and by expansion of rubber membranes in soil discs. Simple engineering theory was used to relate the stress required to fracture a disc with the applied internal stress. Mean values for the radial stress applied by the earthworms in tunnelling through the discs was 230 kPa. With some assumptions about the distribution of muscles across the worm diameter, it was estimated that the mean maximum force generated by all the longitudinal muscles in any segment was 3.2 N.

Some physical properties of casts of the earthworm Aporrectodea rosea were examined and compared with the properties of aggregates from the bulk soil. Cast shape was quantified by three ratio methods and two mathematical spectra methods, using data obtained by two-dimensional scanning. Shapes were compared with previously published descriptions of “modexi”. The tensile strength of dry casts was measured by the indirect tension method and was found to be approximately 2.5 times greater than that of dried aggregates of similar size. Tensile strengths are used to predict that beds of casts are less compactable than beds of aggregates. From relationships between soil water content, matric potential and undrained shear strength of fresh earthworm casts, the mean pressure applied to soil as it is remoulded by passing through the earthworm gut is estimated to be 259 Pa.

Summary Soil fungi are considered to be an important food source for earthworms. Selection experiments were carried out in order to study the preferences of earthworm species for a variety of soil fungi. Nine fungal species (Cladosporium cladosporioides, Rhizoctonia solani, Mucor sp., Trichoderma viride, Fusarium nivale, Phlebia radiata, Glaeophyllum trabeum, Coniophora puteana, Coriolus versicolor) were grown separately in centrifuge tubes on sterilized sand with potato dextrose. Tubes containing different fungal species, 8–9 per experiment, were arranged in a food choice arena. The preference for the fungi of 5 different earthworm species (Lumbricus terrestris, Lumbricus castaneus, Aporrectodea caliginosa, Aporrectodea rosea, Octolasion cyaneum) was tested by adding one specimen per chamber. Removal of sand from the tubes within 6 days was used as the indicator of preference by earthworms. The food preference of earthworms irrespective of ecological group followed a general pattern. F. nivale and C. cladosporioides were the preferred fungal species, followed by fast-growing species such as Mucor sp. and R. solani. In contrast, basidiomycetes were generally refused. The epigeic species L. rubellus had the strongest preference for a single fungal species, in contrast the endogeic species A. rosea fed more evenly on different fungal species. We conclude that early successional fungal species are used as cues by earthworms to detect fresh organic resources in soil.

After earthworms of the species Aporrectodea caliginosa and A. rosea had burrowed in compacted cores of soil for 68 days the cores were sectioned horizontally. The upper surface of each sectioned layer of soil was photographed before it was dissected and the dimensions of all burrows within the layer measured. Volume densities calculated from the direct measurement of burrows were compared with the values calculated by stereology from data obtained from two image analysis methods, computerised image analysis and point counting with a systematic lattice. The assumption implicit in all stereology calculations was satisfied for this experiment in that the burrows of both species showed no preferred orientation in the compacted soil. Computerised image analysis could not measure the density of all burrows in the photographs because of the lack of contrast between cast-filled burrows and the soil and the complex shapes of the burrows. Although the volume densities of A. caliginosa burrows calculated from point counts were correlated with the values calculated from direct measurement, point counting over-estimated volume densities by two to three times. In the experiment, A. rosea produced too few airfilled burrows for the lattice to detect. The relative ratios of air-filled to cast-filled burrows calculated from the point counts suggested that approximately two-thirds and eight-ninths of the burrows of A. caliginosa and A. rosea, respectively, were filled with casts.