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Mercury (Hg) is a contaminant of global importance but its fate and impact in soils is overlooked. Earthworms are responsible for soil bioturbation but their interaction with Hg is poorly described. This study was conducted on a Hg contaminated site in Switzerland. The objectives were to determine the Hg tolerance of Lumbricus terrestris and Aporrectodea nocturna, and their capability to redistribute Hg from deep contaminated soil layers to remediated topsoil layers. Earthworms were incubated for 30 days in 35 cm height soil columns with soil Hg contents ranging from 0.19 to 83 mg Hg kg−1. 100% survival was observed except for the highest soil concentration (67% survival). Corresponding bioaccumulation factors ranged from 1 to 17. In parallel, Hg upward transfer by earthworms from a deep contaminated soil layer to a non-contaminated 40 cm thick surface layer was studied in 80 cm repacked soil columns. After 70 days, total Hg content of surface casts was 10 times higher than the non-contaminated soil. Furthermore, the 25–30 and 35–40 cm layers had a Hg content of 0.537 and 8.54 mg Hg kg−1 respectively, both exceeding the local threshold intervention value of 0.5 mg Hg kg−1. We concluded that (i) earthworms not acclimated to polluted soils can survive Hg levels as high as 85 mg Hg kg−1 in mesocosms, and (ii) a 40 cm thick remediated layer would be recontaminated after 6 months of earthworm activity if the underneath layer remained contaminated.

A glasshouse experiment was conducted to study if glyphosate spraying has immediate short-term effects on the growth, reproduction and residue incorporation of the earthworm species Lumbricus terrestris L. The experiment simulated post-harvest conditions in no-till cereal cultivation, where L. terrestris often abound, and glyphosate is widely used. Pairs of adult, field-collected L. terrestris (median total mass 11.2 g fresh weight) were kept in fine sand-filled cylinders, with chopped wheat straw on the soil surface as feed. The treatment cylinders were sprayed with glyphosate at normal field application rate [Rodeo® XL 3.0 l ha−1, resulting in 1080 g a.i. ha−1 and “Contact” surfactant (0.5 l ha−1)]; the controls were sprayed with water (N = 12 for both). The treatment and control cylinders were maintained for two months at +15 °C, approximate 60% air humidity and 12h:12h light:dark cycle. All individuals survived the experiment. There was no difference in L. terrestris mass change over the experiment, with an average weight change of +0.96% in glyphosate treatment and −0.93% change in the control (p = 0.66). Glyphosate treatment and control did not differ in cocoon production rate (31 vs 28 cocoons cylinder−1 respectively; p = 0.30). The straw incorporation was slightly but not significantly lower in glyphosate-treated soil (decline in surface straw mass 27.5% vs. 30.5%; p = 0.07). The glyphosate treatment applied represents a commonly used practice in spring cereal cultivation, and it did not affect negatively L. terrestris. The varying study results on the effects of glyphosate on earthworms – and on L. terrestris in particular – may partly arise from notable variation in application rates and the formulation-surfactant combinations used in different experiments which needs to be considered in the ecological risk assessment of glyphosate use.

Earthworm species contribute to soil ecosystem functions in varying ways. Important soil functions like structural maintenance and nutrient cycling are affected by earthworms, thus it is essential to understand how arable farm management influences earthworm species. One aim of arable field margin strips and non-inversion tillage is to enhance agrobiodiversity, however their influence on earthworm species assemblages remains unclear. In particular, on-farm studies conducted over multiple years that capture variability across the landscape are rare. The current study monitored earthworm species assemblages on 4 farms in Hoeksche Waard, The Netherlands, from 2010 to 2012. It was hypothesised that arable field margin strips (FM) and non-inversion tillage (NIT; a reduced tillage system that loosens subsoil at 30−35 cm depth) would have higher earthworm species abundances (epigeics and anecics in particular), soil organic matter, and soil moisture than adjacent mouldboard ploughing (MP) fields, and that earthworm numbers would decrease with distance away from FM into arable fields (MP only). FM contained a mean total earthworm abundance of 284 m −2 and biomass of 84 g m −2 whereas adjacent MP arable fields had only 164 earthworms m −2 and 31 g m −2 . Aporrectodea rosea , Lumbricus rubellus , Lumbricus terrestris , and Lumbricus castaneus were significantly more abundant in FM than adjacent arable soil under MP. However, no decreasing trend with distance from FM was observed in earthworm species abundances. A tillage experiment initiated on the farms with FM showed that relative to MP, NIT significantly increased mean total earthworm abundance by 34% to 275 m −2 and mean total earthworm biomass by 15% to 51 g m −2 overall sampling dates and farms. L. rubellus , A. rosea , and L. terrestris were significantly more abundant overall in NIT than MP. FM and NIT positively affected earthworm species richness and abundances and it is noteworthy that these effects could be observed despite variation in environmental conditions and soil properties between samplings, farms, and crops. Higher top-soil organic matter and less physical disturbance in FM and NIT likely contributed to higher earthworm species richness and abundances. The anecic species L. terrestris (linked to water infiltration and organic matter incorporation) was more abundant in FM, but densities remained very low in arable soil, irrespective of tillage system.

Earthworms dominate invertebrate biomass in many non-acidic terrestrial ecosystems and represent key detritivores. Anecic earthworms live in the soil but primarily feed on soil surface litter. Recent studies indicate that predation of seeds and seedlings may also contribute to earthworm nutrition. However, the biological significance of this behavior is unknown. Here, we present to our knowledge the first photographic and video evidence that the anecic earthworm species Lumbricus terrestris L. attacks living plants and damages leaves still attached to plants. This behavior could be observed repeatedly and in different locations, indicating that it may be a common process. Though based on uncontrolled observations and in situations of low litter availability, this herbivore behavior suggests that the role of earthworms within ecosystems should not be restricted to litter burial and decomposition, but should include aboveground herbivory. Our observations do not allow us to determine with certainty if the earthworms directly fed on fresh plant material or – more likely – transported it to its permanent burrows to facilitate microbial decay. We propose that this behavior and its implications for the composition and functioning of plant communities merits further scientific attention. For instance, given the detrimental effects of some common molluscicides on earthworm performance, assumed mollusk effects on plant growth and seedling survival reported in previous studies could be – at least in part – due to the action of anecic earthworms. Future studies should investigate the biological significance and the context-dependency of this behavior.

A microcosm experiment was performed to study the possible fragmentation of Cry1Ab protein from Bt maize (MON810) in the earthworm gut and cast after ingestion by Lumbricus terrestris L. using a Western Blot technique. The gut was further differentiated into foregut, midgut, and hindgut. Additionally, we investigated the concentration of Cry1Ab in these samples by using DAS-ELISA. The results revealed a significantly greater decrease in Cry1Ab concentration in Bt maize litter during the 14-day experiment in the earthworm treatment than in the control without earthworms. Concentrations were further significantly decreased in the foregut compared to Bt maize litter, and from foregut to midgut. The digestive system of the foregut can be localized to be the most important compartment along the whole gut for the fate of Cry1Ab protein during digestion. Cast material showed a slight increase in Cry1Ab concentration relative to the hindgut. We found a considerable fragmentation of Cry1Ab protein in the direction Bt maize – foregut – midgut from 65 kDa size to 31, 23 and 17 kDa size, respectively, whereas fragments of 23 kDa appeared to be the most abundant. No fragments were found in the hindgut and casts. We suggest, that fragments smaller than 17 kDa size were quantified by DAS-ELISA which in turn could not be detected in the Western Blot. It is concluded that detritivorous earthworms accelerate the fragmentation of Cry1Ab protein from MON810 maize litter.

A laboratory experiment was performed to assess the impact of ecologically different earthworm species on soil water characteristics, such as soil tension, water content, and water infiltration rate. Three earthworm species ( Lumbricus rubellus , Aporrectodea caliginosa , Lumbricus terrestris ) were exposed in soil columns (diameter 30 cm, height 50 cm) for 100 days with a total fresh earthworm biomass of 22.7 ± 0.4 g per column, each in duplicate. Each column was equipped with tensiometers at 10 and 40 cm and FD-probes at 10 cm depth, to continuously measure the temporal development of soil tension and soil moisture. Additionally, 30 g of sieved and rewetted horse manure was placed on the soil surface as a food source. Precipitation events (10 mm) were simulated at day 28 and day 64. At the end of the experiment the water infiltration rate and the runoff at 55 cm depth were determined. The results showed considerable evidence, that ecologically different earthworms modify soil water characteristics in different ways. The anecic L. terrestris and the endogeic A. caliginosa showed the tendency to enhance the drying of the topsoil and subsoil. Their intensive and deep burrowing activity might enhance the exchange of water vapor due to a better aeration in soil. In contrast, the epigeic L. rubellus tended to enhance the storage of soil moisture in the topsoil, which might be linked to lower rates of litter loss from soil surface and thus a thicker litter layer remaining. A. caliginosa led to considerable higher water infiltration rates and faster water discharges in the subsoil, relative to the other species, probably due to a high soil dwelling activity.

An investigation of earthworms across a sand dune system in NW England examined species distribution and abundance with respect to soil physico-chemical conditions and management. Replicated 0.1 m2 quadrats were examined every 50 m along 700 m transects across areas of vegetation succession and samples were then taken every 10 m where earthworms were first encountered. A translocation of Aporrectodea longa assessed the ability of this species to live in soils with a high sand content and laboratory work examined growth, maturation and survival of this species in soils with increasing proportions of sand (0–100%). Nine earthworm species were found on the dunes, but none in yellow dunes where organic matter (OM) content was

The fate of the insecticidal Cry1Ab protein from crop residues (leaves and roots) of the transgenic maize variety MON810 was studied in the presence and absence of two earthworm species ( Lumbricus terrestris , Aporrectodea caliginosa ; separate incubations) in soil microcosms. The recombinant Cry1Ab protein was quantified using a highly sensitive ELISA. Control microcosms received corresponding non-transgenic plant material. All earthworms survived in the microcosms over a period of 5 weeks, irrespective of whether they received MON810 or non-transgenic plant material. Weight loss was observed for both earthworm species, independent of the plant material or transgenic modification. A strong decline of immunoreactive Cry1Ab in plant residues (mean initial concentration approx. 5000 ng g −1 ) of MON810 was observed in all treatments, but in microcosms with earthworms this decline was significantly higher with less than 10% of the initial Cry1Ab concentration remaining after 5 weeks. Cry1Ab concentrations in casts were only 0.1% of those found in remaining plant material of the respective microcosms. No immunoreactive Cry1Ab proteins were found in earthworm tissues (threshold of detection: 0.58 ng g −1 fresh weight). No further decline was found for Cry1Ab concentrations in casts of A. caliginosa during a subsequent period of 3 months of incubation in bulk soil ( −1 ) after removal of the earthworms from the microcosms, while in casts of L. terrestris the concentration decreased from 0.4 to below 0.1 ng g −1 . In conclusion, this study demonstrates that earthworms enhance the decline of immunoreactive Cry1Ab proteins from maize residues.

Down House was Charles Darwin's home from 1842 until his death in 1882 and where he wrote “The Formation of Vegetable Mould through the Action of Worms”. The work described here is based upon passages from this book and from further observations on earthworms in this area. General observations were made in addition to systematic sampling in areas selected either from signs of earthworm activity, habitat type or in direct relation to Darwin's documented work. Greatest species richness (n = 9) was found in Middle Field. Greatest earthworm density was present in Darwin's Kitchen Garden (715 m−2) with the largest associated biomass (261 g m−2). Aporrectodea longa was the most abundant species. Lumbricus terrestris, described by Darwin in terms of its behaviour, but not directly named, was located in relatively low numbers, but its diagnostic middens and associated burrows were easily detected. Earthworms associated with Darwin's cinder and chalk application experiments were also examined. In total, 19 of Britain's 28 earthworm species were located within the nominated World Heritage Site.

To monitor the effects of liming on forest ecosystems, experimental plots were installed in forests in mid-western Germany. In addition to soil chemical indices, earthworm communities were investigated on these plots about 15 years after first lime applications took place. As a “natural reference”, communities were compared to earthworm records that derived from a beech forest on limestone. In the non-acidified plots that had never been limed only epigeic earthworms were detected in small numbers and low species richness. Forest liming caused higher pH and a higher base saturation in the mineral topsoils. To a large extent, epigeic earthworm species seemed to benefit from this and had increased in number and biomass at all three different locations selected for the investigations. The epigeic dominated communities were completed by anecic Lumbricus terrestris that was rarely found in some of the samples from one location and a number of endogeic species that showed a very patchy distribution in limed plots. In contrast to this, the soil of the beech forest on limestone showed a different community composition. It was dominated by endogeic species in abundance and by anecic species in biomass. On limestone the total biomass of earthworms clearly exceeded the biomass values from all other plots. In conclusion, a long-term support of forest earthworm fauna due to liming was detected. This support was mainly effective for epigeic species, but in some cases for endogeic and anecic species, too.

In this study we compared short-term, sub-lethal responses of two different earthworm species, Eisenia fetida and Lumbricus terrestris, exposed to Cd (100 mg/kg) under laboratory conditions. Biological responses at the cellular and molecular genetic levels of organisation were measured. First, the Neutral Red uptake test was performed on extruded coelomocytes. Observations showed a significant reduction in cell membrane integrity in E. fetida exposed to Cd, whilst L. terrestris membranes appeared to be unaffected. Second, metallothionein 2 (MT2) gene expression levels were measured by Q-RT-PCR. Observations showed a significant up-regulation of the Cd-inducible metalloprotein in both species. Transcriptome measurements indicated that basal MT gene expression levels were higher in E. fetida than in L. terrestris, but Cd-induced MT2 up-regulation was approximately similar in samples from the two species. In conclusion, the susceptibility of coelomocyte membranes to Cd-evoked toxicosis is not correlated with Cd-induced MT2 expression levels.

The responses of soil microorganisms to the action of gut fluids of three earthworm species, Aporrectodea caliginosa , Lumbricus terrestris and Eisenia fetida were investigated. It was found that the midgut fluid taken form anterior part of the digestive tract could suppress formation of colonies of bacteria, inhibit the germination of spores and reduce the radial growth rate of some fungal colonies. Heating the midgut fluid at 98 °C for 10 min did not eliminate its suppressive activity. This suggests that a non-protein compound ( s ) is involved in this action of the midgut fluid. The suppressing effects were shown to be selective towards soil bacteria. However, the responses of microbial cells to the midgut fluid did not correspond to the taxonomic affiliation of the microorganisms tested. The mechanism of the suppressing effect might be a destruction of microbial cell membranes, as demonstrated for the gut of soil millipedes. The selective activity of the gut fluid of earthworms could be a significant factor for the animal's nutrition as well as for regulating the steady state of the intestinal microbial community, and modification of microbial communities in soil.

Earthworms are suggested to play an important role for the plant diversity of grassland ecosystems. Here we tested whether (i) Lumbricus terrestris L. selectively feeds on seeds of grassland species, (ii) feeding patterns match with seed species present in surface casts in a permanent grassland, and (iii) grassland plant seeds deposited in different soil depths are transported by earthworms. Food choice experiments with 10 plant species (3 grass spp., 4 non-leguminous herb spp., 3 leguminous spp.) showed that earthworms significantly selected between the offered seeds and generally preferred herbaceous species over grass species. Seed species in grassland surface casts did not correlate with seed species preferred by earthworms in the feeding experiment. Mesocosm experiments with L . terrestris in sterilized soil where 3500 seeds m −2 of Dactylis glomerata (grass), Taraxacum officinale , Rumex obtusifolius (non-leguminous herbs) and Trifolium repens (legume) were deposited in 2, 10, 20 and 30 cm depth showed a significantly different species-specific transport of the seeds both downward and upward the soil profile. Dependent on the initial deposition depth between 26% (seeds initially at 10 cm depth) and 56% (20 cm depth) of the seeds were transported by earthworms. After 90 days on average 585 germinable seeds m −2 of D . glomerata , 94 seeds m −2 of T . officinale , 38 seeds m −2 of R . obtusifolius but no seeds of T . repens were transported from deeper soil layers to the soil surface. Results suggest that seed herbivory and seed transport are important mechanisms by which earthworms can selectively alter the diversity of grassland ecosystems.

Speculation exists as to the function(s) of the Lumbricus terrestris midden, but collection of organic matter, inorganic objects and maintenance through cast addition/incorporation suggests that it plays an essential role in the life cycle of this species. Middens act as a focus for soil micro-fauna and encourage microbial activity. This study examines use of L. terrestris middens by earthworms, other than the burrow resident. Middens and associated samples were collected from a woodland site examined over a full year. Sampling involved removal of the intact midden (sample A), and a soil core immediately beneath the midden (sample B). A control core (sample C) was collected within 15 cm of sample B. Mass and sexual condition of the resident L. terrestris, was also examined, where possible. Midden and core samples were hand-sorted for the presence of earthworms in the laboratory, mature individuals were preserved in formaldehyde and identified, whereas immature animals were grown to maturity for identification. In late autumn, winter and early spring significantly (p < 0.05) more earthworms were associated with soil below middens than control samples. Ten earthworm species were found associated within and directly beneath middens. Epigeic and endogeic species were both well represented within the midden itself and endogeic species, such as Aporrectodea caliginosa, dominated in the soil beneath the midden. Juvenile L. terrestris were found within and beneath middens during spring sampling. L. terrestris middens may therefore influence earthworm distribution on a micro-scale.

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.

Negative interactions between earthworms may arise from high earthworm population densities. Under high populations in the field, niche separation or migration away from competitive pressure may help to regulate a multi-species population to a given level. This may not be possible in laboratory experiments, leading to an increase in competitive interactions which may alter earthworm growth rates and affect decomposition and nutrient mineralization processes. The objective of this experiment was to determine how growth rates of the endogeic earthworm Aporrectodea caliginosa Sav. and the anecic earthworm Lumbricus terrestris L. are affected by increasing population density and container size in both single- and multi-species cultures. Earthworm growth responses were compared in 1-L cylindrical pots containing disturbed soil and in 2.3-L PVC cores containing undisturbed soil. The relationship describing intra- and inter-specific competition was not affected by container type for both species. Nonetheless, decreasing the container size restricted the growth of L. terrestris in both single- and multi-species cultures, but only restricted the growth of A. caliginosa in multi-species cultures. For both species, a population density greater than one individual per litre reduced earthworm growth rates significantly, while weight loss in monocultures occurred when there were more than 10 A. caliginosa , and more than three L. terrestris per litre. Growth rates of both species were restricted in all population density treatments including the lowest of 0.9 individuals per litre. Further work is needed to find the population density at which growth rates are not affected and which may be used as an appropriate population in laboratory pot experiments to measure the effects of earthworms on soil processes and plant growth.

An inoculation of the deep burrowing earthworm Lumbricus terrestris L. was carried out for soil amelioration purposes at an arable field on heavy clay in southern Finland. L. terrestris , whilst entirely absent from the field and its immediate surrounding, was present in many other local soils. Prior to inoculation, field management was changed in favour of L. terrestris by improving the subdrainage and by implementation of reduced tillage. In Autumn 1996, 82 earthworm inoculation units (EIUs) were introduced in three transects at one end of the field, one transect lying within a permanent grass strip outside the cultivated area. In Autumn 1998, L. terrestris had persisted outside the cultivated area with maximum density of 28 ind. m −2 (median: 0 ind. m −2 ). No individuals were found inside the field. In Autumn 2003, maximum density was 43 ind. m −2 (median: 9 ind. m −2 ) outside the cultivated area, with evidence for 8 m dispersal from inoculation points (1.1 m year −1 ). In 2003 individuals were also found in low densities inside the field, close to subdrains, with a maximum density of 4 ind. m −2 . Results call for critical evaluation of this inoculation practice.

This study is a first approach of the impact of soil compaction due to trafficking by machinery on earthworm burrow systems. To this end, two experiments were established. In the first one, microcosms were incubated in the laboratory for 70 d with Lumbricus terrestris or Aporrectodea giardi. In the second experiment, soil cores were excavated from a sugar beet field mainly colonised by L. terrestris and Aporrectodea caliginosa. The cores were then artificially compacted at 0.12 MPa or 0.25 MPa (which corresponds to the compaction due to trafficking by machinery in the field) or remained non-compacted. The whole cores were submitted to an X-ray computed tomography scan. This method allowed to compare the characteristics of the entire burrow system (total and mean burrowed length, mean length and number of burrows) and of the burrows themselves (number, area and roundness of pores constituting the burrows) in the compacted and non-compacted cores. The results showed that soil compaction contributes to close numerous pores, reduce mean length of burrows and increase the number of fragmented burrows. We concluded that soil compaction affects to a large extent the functionality of burrow systems by fragmenting them and affecting their continuity. This impact increases with the intensity of compaction. The applied soil compaction mainly affected the burrows located in the upper part of the soil. From a general point of view and especially for the upper part of the cores, horizontal burrows seemed to be more affected by compaction than vertical or oblique ones. Globally, the effects of soil compaction were especially observed at the greatest applied pressure (0.25 MPa). At 0.12 MPa, the damage to the burrows was less obvious.

Restored soils are often low in organic matter (OM). As a result, OM is applied to increase soil fertility. Earthworms can assist soil incorporation of OM, but feeding behaviours, and as a result their roles in this process, differ between species. Laboratory experiments examined the effects of OM availability on the growth and behaviour of Aporrectodea longa and Lumbricus terrestris. Hatchling growth was recorded from 1 l vessels containing soil and OM (separated cattle solids), either surface applied (SUR) or mixed into the soil (MIX). Growth of L. terrestris was also recorded where separated cattle solids (SCS) were concentrated in bands at the surface (SUR) or at depths of 0.03 (UPP) or 0.08 m (LOW). In a further experiment, L. terrestris and L. rubellus were kept in mono-species cultures and paired combination, in treatments with selected SCS placements, which allowed assessment of OM position on species interactions. After 28 weeks, both L. terrestris and A. longa exhibited significantly greater growth rates (P

International audience; Micro-scale changes in earthworm communities and ground cover types were studied along five transect lines in an unmanaged beech forest (Fontainebleau forest, France). Spatial patterns were interpreted in the light of interactions between earthworm species and forest architecture, ground vegetation and quantity as well as quality of litter. The anecic Lumbricus terrestris was associated with patches of the grass Melica uniflora, with poor litter cover, while most epigeic species were favoured by accumulation of litter in the absence of grass vegetation. The endogeic Aporrectodea caliginosa avoided, at least in summer time, 4-year-old gaps opened by wind storms. Under the shade of beeches, the evergreen spiny shrub Ruscus aculeatus, and in opened areas the giant herb, Phytolacca decandra, seemed repellent to most earthworm species.

Subsurface drainage induces systematic spatial variability in soil properties which may be reflected in the abundance and distribution of soil organisms. We compared the population density of the deep burrowing earthworm Lumbricus terrestris L. above and between tile subdrains in 41 sample pairs on an eight hectare grass field. Above the drains the median number of individuals was twice as high and their total fresh mass five times as high as between the drains (4.5 vs. 2.1 individuals m-2 and 9.6 vs. 1.9 g m-2, respectively). The mean difference (above drain – between drains) was 2.5 individuals m-2 (95% CI = 1.0 to 4.0) and 6.6 grams m-2 (95% CI = 3.6 to 9.6). The relatively larger difference in fresh mass was due to a high proportion of adult individuals above drains. One likely explanation for the pattern of abundance is that the lowered water table level near the drains provides an environment beneficial for the population growth of L. terrestris. Due to the role of L. terrestris burrows as flow paths of percolating water the observations may have implications on subdrain function.

To study the effects of earthworm casting on organic matter dynamics, control soil and casts were added as a surface layer (Horizon I) to perspex cylinders containing a ‘base’ soil depleted in organic C (Horizon II). Three treatments with different Horizon I were used; a control containing uningested soil and oak litter (Quercus petraea (Mattuschka) Lieblein), cast derived from the same substrates, and a third (Ew+cast) where cast as well as endogeic (Aporrectodea caliginosa Savigny, Allolobophora chlorotica Savigny) and anecic (Lumbricus terrestris L.) earthworms were included. These were monitored over a 2 1 2 year period. Moisture fluctuations were reduced and higher amounts of organic matter and C were present in Horizon I with the cast treatment after 2 years. In addition, the proportion of clay C (and to a lesser extent light fraction) in Horizon I decreased significantly in the control and cast treatments while there was a corresponding increase in the proportions of silt C. Overall, earthworm activity had a limited effect on C distribution in the particle size fractions studied, though the dynamics of organic matter/particle associations may require more than 2 1 2 years before clear patterns emerge.

In comparison to the surrounding soil, hot spot effects of middens of the epianecic earthworm Lumbricus terrestris were determined under different field conditions on a loamy sand. The impact of 3 different management systems was studied: 1. unmulched; 2. straw mulching; 3. intermediate crop: Sinapis alba. Furthermore, we considered 2 different crops (bean, lupine) and their growth stages. We monitored different enzyme activities and abiotic parameters of soil at 6 sampling dates between April and August 1998 parallel to abundances of microfauna (soil protozoa) and mesofauna (Enchytraeidae, Collembola, mites). The analysis of earthworm middens revealed enhanced enzyme activities and increased mesofaunal abundances. Differences between midden and reference samples were significant during the whole vegetation period and became maximal during ripening of crops. We found a distinct but not significant increase in individual numbers of soil flagellates in midden areas during leafing and heading of crops. Values of the studied parameters tended to be higher in bean plots but generally the crop impact on midden properties was not significant. Our results showed a significant positive synergistic effect between earthworm middens and intermediate crop. Straw mulching supported the hot spot effects of middens.

The aim of this study was to investigate the effects of different mulch types on the quality and quantity of casts of different lumbricid earthworm species. Nutrient contents (organic carbon C org , total nitrogen N t and inorganic phosphate Pi), and acid phosphatase activity (SPA) of earthworm casts and soil aggregates were measured and then compared. This short time experiment was conducted in the laboratory, simulating field conditions of mulch management in temperate agroecosystems. In microcosms, the two common field species Lumbricus terrestris and Octolasion cyaneum were inoculated. Barley, lupin, maize, or sugarbeet were used as mulch according to amounts usually applied in the field. Nutrient contents and phosphatase activity in worm casts were generally enhanced compared to the soil. Nutrient values were higher in the casts of the detritivorous L. terrestris than those of the geophageous O. cyaneum . Conversely, the phosphatase activity was increased in the casts of O. cyaneum compared to L. terrestris in case of the barley and sugar-beet treatments. Cast production was related to the earthworms' change of biomass (ΔB) as well as, in the case of L. terrestris , to nitrogen content of the mulch. Due to their chemical compounds, the mulch types influence both the food selection of the worms and the acceptance by microorganisms.

Earthworms were maintained in two types of soil-filled mesocosm. Type 1, designed for use in soil-inoculation studies, was only 0.15 m deep. Sampling revealed the position at which cocoons were deposited by earthworms in mono-species culture. Whilst adequate for shallow-working worms, larger species may have experienced restricted burrow formation and associated cocoon deposition. Therefore, Type 2 mesocosms (1.0 m deep) were also used. Here, earthworms were found to burrow throughout the soil columns, but cocoons were mainly deposited within 0.25 m of the soil surface (95% overall). The deepest cocoon deposition was at 0.4 m by Lumbricus terrestris, although 45% of the cocoons for this species were located in the upper 0.05 m of the soil, compared with 70% and 71% for Aporrectodea longa and Octolasion cyaneum, respectively. Comparisons between mesocosms showed that their depth affected cocoon distribution in the soil and that differences were also present compared with field-collected results. Reasons for this are discussed, as are implications for soil inoculation with earthworms. If cocoons are viewed as a potential inoculum for soil restoration work, their harvesting and spreading in soil may assist successful colonisation.