Effects Of Earthworm Activity Research Articles

Removal of sulfamethoxazole and antibiotic resistance genes in paddy soil by earthworms (Pheretima guillelmi): Intestinal detoxification and stimulation of indigenous soil bacteria

Vermiremediation, which use earthworms to remove contaminants from soil, has been proven to be an alternative, low-cost technology. However, the effects of earthworm activity, especially the degraders in earthworm intestines, on the fate of sulfamethoxazole (SMX), and the effects of intestinal bacteria on degrading bacteria in soil are unclear. In this study, the effects of earthworms on the fate of SMX and related antibiotic resistance genes (ARGs) were investigated. Special attention was paid to the impact of earthworms on SMX degradation efficiency, degradation products, related ARGs, and degraders in both soil and earthworm intestines; the effect of intestinal bacteria on soil bacteria associated with SMX was also studied. Earthworms significantly accelerated SMX degradation by both intestinal detoxification and the stimulation of indigenous soil bacteria. Compared with the treatment without earthworms, the treatment with earthworms reduced SMX residues by 25.1 %, 49.2 %, 35.7 %, 34.2 %, and 35.7 % on the 10th, 20th, 30th, 60th, and 90th days, respectively. Compared with those in soil (treated with earthworms), the SMX residues in wormcasts were further reduced by 12.2–29.0 % from the 2nd to the 20th day, producing some unique anaerobic degradation products that were distinct from those in the soil. In earthworm intestines, SMX degradation was enhanced by bacteria of the genera Microvirga, Sphingomonas, Methylobacterium, Bacillus, and Tumebacillus. All of these bacteria (except Bacillus spp.) entered and colonised the soil with wormcasts, further promoting SMX degradation. Additionally, earthworms removed a significant number of ARGs by increasing the fraction of potential SMX degraders and inhibiting the potential hosts of ARGs and int1. This study demonstrated that earthworms could remediate SMX-contaminated soil by enhancing the removal of SMX and ARGs.

Effects of earthworm activities on soil nutrients and microbial diversity under different tillage measures

As a typical macrofauna in soil, earthworms alter soil structure through a series of activities, including feeding, digging, and excretion, thereby affecting farmland soil nutrients and microbial diversity. In this study, we evaluated the influence of earthworms on soil nutrient distribution and soil microbial diversity, under different tillage measures. Three cultivation methods [tillage (CT), no-tillage (NT), and no-tillage with straw (NTS)] were applied to the field. Five earthworm densities (0, 20, 50, 100, and 200 individuals/plot) were tested under each cultivation mode. Our findings showed that earthworm density improved organic C, N, and P contents in the tilled soil layer (0–30 cm). Contrastingly, in conventional tillage (CT) treatment, increases in earthworm density reduced the total N and P contents and increased the organic C content of the soil. Greater earthworm densities were associated with higher soil microbial abundances and diversities under NTS treatment, whereas the opposite effect was observed under CT treatment. Different earthworm densities also resulted in significant structural changes in the soil microbial community. Overall, these findings suggest that under the same farming method, earthworm density affects soil microorganism composition and diversity as well as soil environmental factors.

Mycorrhizal nitrogen uptake of wheat is increased by earthworm activity only under no-till and straw removal conditions

A large part of crop nutrient uptake occurs through the interaction of roots with symbiotic arbuscular mycorrhizal fungi (AMF). However, it is still an open question how straw management and earthworm activity affect AMF community structure and their nitrogen-transferring function in wheat. A split-plot field experiment was conducted to address this question. Three straw management regimes including different tillage treatments (no-till with no straw, NTNS; rotary tillage with straw return, RTSR and ditch-buried straw return, DBSR), and two earthworm treatments (no earthworm, −E; and earthworm addition, +E) were conducted. The AMF community structure in the wheat roots was characterized with high-throughput sequencing, and its function in terms of N acquisition was measured with 15N isotope tracing through hyphal in-growth cores. Our results showed that both the DBSR and RTSR treatments significantly changed AMF community composition and enhanced the mycorrhiza-mediated plant N uptake when compared to NTNS. The effect of earthworm activity on AMF community composition and mycorrhiza-mediated N uptake strongly depended on the straw management regimes. While earthworm presence increased AMF dominance (+32.9%) and mycorrhizal N uptake (+2.05-fold) under straw removal, they decreased AMF dominance (−30.4% and −41.9% respectively) and mycorrhizal N uptake (−37.3% and −34.3% respectively) under both DBSR and RTSR treatments in comparison with the absence of earthworms. It is concluded that straw addition shifts the AMF community structure and increases N uptake by the host plants; and that the effect of earthworms on AMF community structure and functioning depends on the straw management regime. The results suggest that straw management and its interaction with earthworms can affect mycorrhiza-mediated plant N uptake, possibly through altering some dominant AMF taxa.

Interactive Effects of White-Tailed Deer, an Invasive Shrub, and Exotic Earthworms on Leaf Litter Decomposition

Herbivore overabundance and species invasions could alter decomposition rates in temperate forests, with consequent effects on carbon sequestration, nutrient retention, and other ecosystem processes. At local scales, herbivores, invasive plants, and soil macroinvertebrates can be important drivers of decomposition, but interactive effects among these different groups are unknown. We tested for the effects of white-tailed deer, Amur honeysuckle, and earthworm activity (manipulated via mesh exclusion) on litter decomposition rates and loss of litter nitrogen (N) in five hardwood forest sites in southwestern Ohio. Each site consisted of a 20 × 20-m deer exclosure paired with a deer access plot; honeysuckle was removed from half of each plot. Effects of earthworm activity were tested using paired litter boxes of fine mesh (0.25 mm; earthworms excluded) or coarse mesh (10 mm; earthworm access). Restriction of earthworm activity in fine mesh treatments slowed litter decomposition and increased retention of N in the litter layer compared to coarse mesh. Deer access interacted with mesh treatments, with faster decomposition occurring in deer access, coarse mesh treatments relative to others. Greater earthworm biomass in deer access plots relative to deer exclosure plots corresponded with more rapid litter decomposition. Honeysuckle presence did not affect litter decomposition, but did increase litter N retention. The interactions between deer and earthworm activity indicate that reductions in deer populations may slow litter decomposition rates, increasing complexity of habitat structure at the soil surface, which relates to habitat for plants and animals.

Influence of the geophagous earthworm Aporrectodea sp. on fate of bisphenol A and a branched 4-nonylphenol isomer in soil

Large amounts of endocrine disrupting chemicals (EDCs) including bisphenol A (BPA) and nonylphenol (NP) are released into the soil due to the application of biosolids. Earthworms are the predominant biomass in many terrestrial ecosystems and profoundly influence the physico-chemical and biological properties of soils. However, information about the effects of earthworm activities on the behaviors of EDCs in soil is still limited. Here, the effects of earthworms on mineralization, degradation, and bound residue formation of BPA and NP were investigated using the 14C tracer technique. The results showed that earthworms did not affect mineralization of BPA, but significantly inhibited bound residue formation of BPA and changed the size distribution of BPA residues within humic substances. Regarding NP, earthworms significantly inhibited mineralization and bound residue formation, and thus significantly promoted the degradation of NP and NP's metabolites in soil. After nine days of incubation, 75% and 46% of the initially applied 14C-BPA and 14C-NP were already present in bound residues, respectively, indicating that the major route of degradation of BPA and NP in soil was bound-residue formation. Among total 14C-BPA or 14C-NP residues accumulated in earthworms, bound residues were also predominant (>50%), implying that risk assessment of EDCs based on their concentrations of free form in earthworms might be significantly underestimated. Taken together, our results suggest that fate of EDCs in soil not only depended on their physico-chemical properties but also was intensively affected by earthworm activities, underlining that effects of earthworms should be considered when evaluating environmental behavior and potential risk of EDCs in soil.

Sewage sludge application strongly modifies earthworm impact on microbial and biochemical attributes in a semi-arid calcareous soil from Iran

Application of municipal sewage sludge (MSS) may modify the influence of earthworm activity on soil microbial and biochemical properties through an increase of substrate availability. However, the effect of earthworm activity on microbial community is poorly known in calcareous soils amended with MSS. Such knowledge would lead to better understanding of how earthworms and microorganisms interact following MSS application in agroecosystems. This study aimed to investigate how MSS application can modify the impact of earthworms on microbial performance and biochemical attributes of a calcareous soil amended with MSS. Experimental treatments were MSS application (without and with 1.5% MSS) and earthworm addition (no earthworm, epigeic Eisenia fetida, endogeic Aporrectodea caliginosa and a combination of the two earthworm species) setup as a 2×4 full factorial experiment using a completely randomized design with three replications for each treatment combination under greenhouse conditions over 90 days. Addition of MSS had a positive effect on the measured biochemical and microbiological indicators of the study soil. Municipal sewage sludge application resulted in a significant (p<0.001) increase in the amounts of microbial biomass carbon (MBC) and basal respiration rate (RR); but without an effect on the level of dissolved organic carbon (DOC). While the presence of earthworms decreased the quantity of DOC and MBC (p<0.001); other soil attributes such as basal respiration rate, the metabolic quotient (qCO2) and the ratio of fungal to bacterial (F/B) respiration were all increased significantly (p<0.001) with earthworm addition. Nevertheless, the magnitude of the earthworm effect was largely dependent upon the MSS treatment. Application of MSS decreased the stimulatory effect of earthworms on soil microbial indicators and this effect was less pronounced in the presence of E. fetida than A. caliginosa species. This is probably due to the preference of epigeic E. fetida to feed on MSS as an essential food resource rather than only feeding and grazing on microbial populations. In contrast, the endogeic A. caliginosa species was not dependent upon MSS as food resources. Moreover, the interaction effect between the two earthworm species on soil microbial and biochemical properties was mostly additive in nature (without interaction) in both MSS-amended and unamended soils. Results indicated that earthworm effect and its interaction with MSS were important factors for soil microbial biomass, community composition and performance and that earthworm effects should decrease in MSS-treated soils.

The effect of earthworm activity on soil bioporosity – Investigated with X-ray computed tomography and endoscopy

Bioporosity in subsoils is strongly influenced by either deep rooting taproots or earthworms, which can affect important properties for plant growth provided by soils. The open question of this study was, in how far the combination of X-ray computed tomography (XRCT) and endoscopy may support the analysis of soil bioporosity and the effects induced by earthworm activity. The hypothesis were that earthworms can re-open, close and re-connect pores as well as change the biopore wall properties (by leaving coatings at the wall) and that with a combination of XRCT and endoscopy much more detailed information about those changes can be observed. Soil monoliths were collected from a Haplic Luvisol (developed from loess) at the experimental station Klein Altendorf (University of Bonn, Germany). The microcosms were then prepared under laboratory conditions in terms of temperature, soil temperature gradient, relative humidity, illumination, watering and fertilizer. The microcosms were examined before cultivation and incubation, and re-examined after one-month earthworm incubation (Lumbricus terrestris L.), three months wheat growth period and shoot harvesting. XRCT and endoscopy were used to qualitatively and quantitatively analyze the soil microcosms. After the incubation with earthworms, physical properties like porosity and accessible surface area of biopores have changed with respect to the original state. Coatings at the biopore walls resulted in smaller pore diameters of large biopores with a diameter >0.5cm, while some of them have previously been pores with diameters <0.5cm. Contrary to this, biopores with a diameter <0.5cm were increased after earthworms, i.e. widened due earthworm passage. It was found that earthworms may have disconnected lateral pores that reach into the bulk soil from the vertical biopores by pore wall coatings. After incubation, biopores lined with fresh earthworm coatings in the monolith increased from 30% to 80%, which may indicate that earthworms potentially have a considerable influence on biopore properties and therefore the physical, chemical and microbiological environment which roots are exposed to in biopores.

Effects of earthworm activity on humus composition and humic acid characteristics of soil in a maize residue amended rice–wheat rotation agroecosystem

The effect of earthworms on humus composition and humic acid (HA) characteristics was studied in a rice–wheat rotation agroecosystem. Experimental plots in the rotation had five treatments, i.e., incorporation or mulching of maize residues with or without added earthworms and a control. Compared with the control, the application of maize residues to soil either alone or in combinations with earthworms strongly affected the humus composition and HA characteristics. In the presence of earthworms, the carbon ratio of HA to fulvic acid (FA), and the alkyl C/O-alkyl C and hydrophobic C/hydrophilic C ratios of HA were slightly higher, while the aliphatic C/aromatic C ratio of HA was slightly lower following maize residue incorporation than the same treatment without earthworms. In contrast, these ratios generally remained almost constant following maize residue mulching. Thus, earthworm activity following maize residue incorporation was more favorable for the HA formation, and was associated with a decrease in aliphaticity of HA, and an increase in its degree of humification and hydrophobicity.

Enhancement of chlorophenol sorption on soil by geophagous earthworms ( Metaphire guillelmi)

Earthworms are the dominant soil biomass of many terrestrial ecosystems and markedly influence the physico-chemical and biological properties of soil; however, little is known about the effects of earthworm activities on the environmental behavior of micropollutants in soil. We studied the sorption and desorption of 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol on geophagous earthworm (anecic Metaphire guillelmi) casts of various aging times and on the parent soil. The casts were characteristic of lower pH and higher content of fine particles (silt and clay) than the parent soil. The sorption of the chlorophenols on the soil and casts were well fitted to linear isotherms, with sorption capacity in the order of pentachlorophenol > 2,4-dichlorophenol > 2,4,6-trichlorophenol. The sorption on the cast with different aging time was quite similar and was higher than on the parent soil. The sorption on the soil did not change between pH 7.07 of the soil and pH 6.76 of the casts. The desorption hysteresis of the chlorophenols on the soil and casts was compound specific and 2,4,6-trichlorophenol showed the highest hysteresis. The higher sorption capacity of the casts was not owing to the lowered pH of the casts, but mainly to the higher fine particles in the casts and the possible changes of nature of the soil organic matter through the earthworm gut passage. Our results indicate that geophagous earthworms may change sorption behavior and thus the bioavailability and transport of chlorophenols in soil. Earthworm effects should be considered when evaluating the environmental behavior and risk of organic pollutants in the ecosystems where earthworms are abundant.

Tree rings detect earthworm invasions and their effects in northern Hardwood forests

Invasions of European earthworms into the forests of northern North America are causing dramatic changes in forest floor structure, vegetation communities, biogeochemical cycling, and site hydrology. However, long-term studies on the effects of invasive earthworms are limited because little data exist on the timing and rate of earthworm invasion at specific sites. We successfully used tree rings to identify the timing of earthworm invasions and the effects of earthworm activity on the Acer saccharum overstory of two recently invaded sites in northern Minnesota, thereby establishing a method to date earthworm invasions at other sites. In addition to identifying a tree-ring signature related to earthworm invasion, we found trees growing in invaded conditions were more sensitive to drought than trees growing in earthworm-free conditions. Increased drought sensitivity by A. saccharum has important implications for possible range shifts under climate change scenarios that include increasing drought frequency and severity.

Earthworm populations under different tillage systems in organic farming

To understand how earthworms could improve soil porosity in no-tillage organic farming systems, the aim of our study was to compare the effect of different tillage systems on earthworm populations, from conventional (traditional mouldboard ploughing, MP and shallow mouldboard ploughing, SMP) to conservation tillage (reduced tillage, RT, direct drilling or very superficial tillage, NT) in three organic arable systems in France (sites A–C). In a second stage, the effect of earthworm activity on soil porosity under the four tillage systems was assessed at sites A and B. Earthworm abundance, biomass and diversity were measured over a 2–3-year period at the 3 sites. During the same period, soil structure (soil profile description and soil bulk density) and open worm burrows in the soil were assessed at sites A and B. After 3 years of experiments, it was found that at 2 sites earthworm abundance and biomass were higher in NT than with ploughing or reduced tillage. The increase of earthworms in NT is mainly due to anecic species increase. Earthworm abundance and biomass tend to decrease regardless of the tillage techniques employed at sites with a ley, and conversely, tend to increase in NT and RT at sites initially ploughed. In the short term, the increase of anecic species in NT has no effect on soil porosity evolution: NT soils were more compacted than those which were ploughed. A long-term experiment is required to assess the effect of biological activity on the physical components of soil in organic farming.

Effects of earthworm activity on fertility and heavy metal bioavailability in sewage sludge

The potential for using earthworms ( Eisenia fetida) to improve fertility and reduce copper and cadmium availability in sewage sludge was tested by laboratory incubation experiments. Results comparing sewage sludge with and without earthworm treatment showed that earthworm activity decreased the contents of organic matter, total nitrogen, but increased the contents of available nitrogen and phosphorus and had no significant effect on the contents of total phosphorus, total potassium and available potassium. After incubation of the sewage sludge with earthworms for 60 days, the contents of Cu and Cd in the earthworms increased with the increase of additional Cu up to 250 mg kg − 1 and Cd up to 10 mg kg − 1. Bioconcentration factors (BCF) were higher than 1 only for Cd when the addition rate was lower than 5 mg kg − 1, which indicates that the earthworms can only accumulate Cd when the concentration of Cd is low in sewage sludge. Bioavailability of Cd and Cu was evaluated by applying sewage sludge with and without earthworm treatment to soil and then growing cabbage plants. The results showed that earthworm treatment increased the biomass of cabbage and decreased the bioaccumulation of Cd and Cu in the cabbage plants.

Effects of earthworm activity and P‐solubilizing bacteria on P availability in soil

AbstractThe effects of phosphate solubilizing bacteria (Bacillus megateriumi) (PSB) and earthworms (Pheretima guillelmi and Eisenia fetida) on phosphorus (P) turnover and transformation in soil were investigated in a laboratory experiment lasting for 21 days. The treatments included soil + P. guillelmi (SW1), soil + E. fetida (SW2), soil + B. megaterium (SB), soil + P. guillelmi + B. megaterium (SBW1), soil + E. fetida + B. megaterium (SBW2), and the control with sterilized soil (control) only. The results showed that the number of B. megaterium. was enhanced in all treatments especially those with earthworms added when compared with the control. Activities of acid phosphatase (pH = 6.5) increased in all treatments, especially in the presence of P. guillelmi with or without PSB (64 % and 38 %, respectively). Significant increases in both inorganic P and water‐soluble P were observed in treatments involving B. megaterium. and earthworms when compared with the control. Inoculation of both earthworms and PSB had significant effects on microbial growth, enzymatic activity, and thus enhanced the release of available P. The dual inoculation of earthworms and bacteria further accelerated P transformation. Different performances observed for the earthworm species were probably due to their different feeding habits and physiology.

Influence of earthworm activity on the abundance of collembola in soil

Effects of earthworm activity on the abundance of collembola were investigated in laboratory experiments and a field experiment on arable land. In the laboratory two earthworm species Aporrectodea caliginosa and Lumbricus terrestris were involved. Folsomia candida could choose between columns of soil which were worked and inhabited by earthworms, those which had a cylindrical, artificial soil pore and those that remained untreated. Working basically with the same design, vessels varied in shape and size. Experiments with A. caliginosa were carried out in planar plastic cuvettes that were divided into three segments, each containing one of the columns of soil described above. Triplets of plastic tubes were used for L. terrestris in the same way. While the soil — a Parabraunerde from loess — was the same in all laboratory experiments as well as in the field experiment, pore space, gravimetric water content, diameter of artificial soil pore and duration of experiments varied. No extra food was provided for the animals. For evaluation the soil columns were fractioned into several depths and extracted after the Macfadyen method. The results showed generally preferences of F. candida for earthworm burrows. In the field experiment near Braunschweig (northern Germany) the natural abundance of earthworms was increased by releasing additional earthworms on plots representing a tramline and a traffic-free control. Two months later eight soil cores were taken from these two plots and from two control plots without raised earthworm abundances. Extraction of collembola was carried out as above. Differences in abundances of collembola occurred only in the heavy compacted plots.

Surface alfalfa residue removal by earthworms Lumbricus terrestris L. in a no-till agroecosystem

Earthworm ( Lumbricus terrestris L.) populations increase in alfalfa ( Medicago sativa L.) and in no-till corn ( Zea mays L.) fields compared to conventionally-tilled fields. The effects of earthworm activity on surface crop residue removal in no-till corn following alfalfa have not been studied. The main objective of this research was to measure earthworm effects on crop residue removal from the soil surface. Soils were Saybrook silt loams (fine-loamy, mixed, mesic Typic Argiudolls) on 2–9% slopes in south-central Wisconsin. We used a mesh-bag method to measure earthworm removal of alfalfa residue and the influence of forage quality on removal of residue from the soil surface. Coarse-mesh bags, with mesh openings 20 × 20 mm 2, which allowed earthworms to remove alfalfa residues from the bags, had significantly greater alfalfa surface residue loss than fine-mesh bags with mesh openings 1 × 1 mm 2, which prevented worms from removing residues. Forage quality of residues did not affect quantity of residue removed. We calculated that the observed populations of 40 to 60 L. terrestris m −2 could remove surface alfalfa residues at a rate that could account for the measured 122 g m −2 October to May biomass losses, given 60 days of suitable feeding weather and based on the measured loss rate of 69 g residue lost m −2 in 30 days. Potential residue removal by earthworms should be addressed in residue management strategies, especially where populations of L. terrestris are large and where crop residues are palatable to earthworms.

Influence of Earthworms on the Sulfur Turnover in the Soil

Abstract The effects of earthworm activity on the concentration and isotopic composition of total sulfur in soils was investigated using batch experiments. Two ecologically different lumbricid species, the anecic Lumbricus terrestris and the endogeic Aporrectodea caliginosa, were used. The earthworms were fed birch leaves, beech leaves, cattle manure or mixed plant litter. All food sources differed isotopically (δ(34)S) from the soil (Parabraunerde). As a reference, one experiment was carried out without additional food. The experimental results show, that both earthworm species influence the total S-content and the δ(34)S-values in the soil by digestion of the different food sources. The differences in the total S-content of the earthworm tissues and in the S-isotopic composition of the casts can be attributed to the ecological differences between the earthworm species.

Effects of biomass and size of Millsonia anomala (Oligochaeta: Acanthodrilidae) on particle aggregation in a tropical soil in the presence of Panicum maximum (Gramineae)

The present study assessed the effect of the tropical geophagous earthworm, Millsonia anomala, on the aggregate-size distribution of a sieved (2 mm), tropical ferruginous soil in the presence and absence of the perennial tropical grass Panicum maximum. The effect of two size groupings and graded biomass densities of M. anomala on soil aggregation was analysed in time and with depth in the containers within which the plants were grown. In the absence of earthworms, aggregation was rapid although limited (13.5% of soil as aggregates >2.0 mm), and probably arose from a combination of microbial activity and physical processes (interparticle bonding due to clays and other colloids). The roots of the test species contributed little to aggregation. In contrast, the effect of earthworm activity on soil aggregation was rapid and important. The effects of both biomass and, to a lesser extent, size were significant. After 79 days, aggregation reached a maximum with 3 g per container of small earthworms (ca. 59% of soil as aggregates >2.0 mm) and a minimum with 1 g per container of large earthworms (ca. 35% of aggregates >2.0 mm). Aggregation was considered to occur through three different mechanisms: (1) A rapid aggregation due to the interactions of colloids; (2) an intermediate aggregation due to a combination of unquantified processes related to earthworm activity (mucus secretion, development of fungus hyphae); (3) egestion of soil as earthworm casts which are stable macroaggregates.

The effect of earthworm activity on the vertical distribution of plant seeds in newly reclaimed polder soils in the Netherlands

The effect of earthworm activity on the vertical distribution of plant seeds in newly reclaimed polder soils in the Netherlands