Earthworm Populations Research Articles

Earthworm species in public parks in Curitiba, Paraná, Brazil.

Earthworms are important macroinvertebrates that provide soil ecosystem services and are also useful environmental bioindicators. Urban areas around the world have major impacts on biodiversity and the objective of the present study was to assess the role of urban parks of Curitiba, Paraná State, in preserving native earthworm species. Earthworm populations were sampled in five parks (Barigui, Tingui, Barreirinha, Passaúna and the Botanic Garden), in two land use systems (grass lawns and secondary forest fragments) in two seasons, summer (November 2013) and winter (June 2014). A total of twelve earthworm species were identified, belonging to six families: Glossoscolex sp.1, Fimoscolex sp.1, sp.2 and sp.3 (Glossoscolecidae), Pontoscolex corethrurus (Rhinodrilidae), Eukerria tucumana (Ocnerodrilidae), Amynthas gracilis, Amynthas corticis, Metaphire californica (Megascolecidae), Aporrectodea rosea and Lumbricus rubellus (Lumbricidae), the latter being the first record for this species in Brazil. In addition, a single unidentified juvenile Dichogaster sp. (Acanthodrilidae) was found. Four new species were found and three out of five urban parks of Curitiba (especially the Botanic Garden) were able to preserve native species, though their abundance was low and exotic species (n=8) predominated, attributed to human disturbance that favors invasion and colonization of exotic earthworms.

Earthworm species in no-tillage agroecosystems and native Atlantic forests in Western Paraná, Brazil.

Earthworm populations often increase with the adoption of no-tillage (NT) practices, but few studies have evaluated earthworm diversity in these agroecosystems. In the present study we assessed earthworm species richness in 40 sites under NT and six native Atlantic forest fragments in Western Paraná, Southern Brazil. At each site earthworms were sampled quantitatively (n=5) and qualitatively (n=5), by handsorting soil monoliths (20 x 20 cm width x 20 cm depth), totaling 460 samples overall. Earthworms were killed and fixed in 96% ethanol, counted and identified. Overall, 18 species were found, in the families Acanthodrilidae, Glossoscolecidae, Megascolecidae, Rhinodrilidae and Ocnerodrilidae, of which 10 were native and eight exotic. No-tillage agroecosystems had larger earthworm populations and higher species richness overall than native forests, although this was mainly due to colonization of these agricultural fields by exotic species. Mostly native species were found in the Atlantic forests, highlighting the importance of these habitats as refugia for native earthworm species conservation.

Dynamics of earthworm species at different depths of orchard soil receiving organic or chemical fertilizer amendments

We investigated the dynamics of different earthworm species through the soil profile, which had received short-term amendments of either organic or inorganic fertilizer in an orchard during the spring of 2016. Earthworm populations were sampled at two consecutive depths of soil on 20 and 60 days after addition of fertilizers. The dominant earthworm species were Eisenia fetida (Savigny, 1826), Dendrobaena veneta (Rosa, 1886), Dendrobaena hortensis (Michaelsen, 1890), Lumbricus terrestris (Linnaeus, 1758) and Aporrectodea longa (Ude, 1885). Seven different types of fertilizers including Urea, Ammonium sulfate (AS), Diammonium phosphate (DAP), Solupotas, NPK (15-5-25), (NPK+OM) and organic manure (OM) as experimental treatments were studied. Fluctuations in earthworm numbers and biomass were attributed to changes in time and depth of sampling, in addition to the types of fertilizers. The results of the means comparison showed that on the 20th day, at 0-20 cm soil depth, E. fetida species abundance was decreased significantly in AS and Urea treatments compared to the control plot (p˂0.05). We highlighted that from epigeic group, D. hortensis species had a better chance to survive and its population in AS treatment was more than that of Urea treatment. Results also showed that the anecic L. terrestris , had a greater tolerance to chemical fertilizers compared to the A. Longa species. The results of this study outline more clear horizons in managing the use of chemical fertilizers while simultaneously maintaining the biodiversity of soil organisms.

Bioconversion of Scotch broom into a high-quality organic fertiliser: Vermicomposting as a sustainable option.

Wild Scotch broom ( Cytisus scoparius (L.) Link) shrubs are widely distributed throughout the world and, in some countries, are considered to be a threat to other plant species. The use of plant biomass from Scotch broom as a fertiliser seems to be the optimum solution for its disposal because it contains considerable amounts of macronutrients. However, its direct application to soils may cause phytotoxicity due to the release of polyphenols, which could negatively affect crop growth. This study evaluated the efficiency of vermicomposting in processing this leguminous plant on an industrial scale. Vermicomposting substantially reduced the biomass of Scotch broom (by 84%), mainly as a result of the loss of volatile solids. Simultaneously, the initial population of earthworms ( Eisenia andrei) increased remarkably throughout the process, offering the possibility of obtaining earthworm protein for animal feed. A nutrient-rich and stabilised peat-like material without polyphenol-associated phytotoxicity was obtained after 42 days of vermicomposting. Lower values of microbial biomass and activity, indicative of stabilised materials, were recorded at the end of the trial. These findings suggest that vermicomposting is an environmentally sound management system for Scotch broom and could easily be scaled up for industrial application.

Soil properties and earthworm dynamics affected by land use systems in western Chitwan, Nepal

Field experiments were conducted in acidic soils of Mangalpur and Fulbari Village Development Committees in western Chitwan, Nepal to study the effects of different land use systems on soil properties and earthworm dynamics. Seven land use systems (cereal based lowland, cereal based upland, vegetable farm land, fruit orchard land, pasture land, forest land and farmer’s field) were used and they were replicated four times in randomized complete block designs. Soil organic matter and total soil nitrogen were significantly higher from pasture land (4.7 % and 0.2 %) and the lowest were from farmer’s field (2.4 % and 0.1 %). However, available soil phosphorous content was significantly higher from cereal based upland (448.3 kg ha-1) and it was the lowest from forest land (13.0 kg ha-1). The highest earthworm count was observed from pasture land (10.1 numbers per trap) than others but it was the lowest from farmer’s field. There were significant positive correlations between soil organic matter content and the earthworm count (r= 0.96**) and between total soil nitrogen content and earthworm count (r= 0.80**). In contrast, a significant negative correlation was observed between earthworm count and available P (r= -0.51**). Correlation between earthworm count and silt content was positive (r= 0.68**) but between earthworm count and sand content was negative (r= -0.64**). However, there were no significant relationships of earthworm count with available K, pH, bulk density and clay content of soils. The soil organic matter, total soil nitrogen and earthworm count were higher from pasture soil than other soils. As soil organic matter, total soil N, available soil P and soil texture regulated earthworm dynamics in soils. Earthworm population may be used as a bio-indicator of soil fertility status and it can be developed as an alternative technique for soil fertility evaluation after quantification and verification from further experiments on earthworm dynamics under different land use systems.Journal of the Institute of Agriculture and Animal Science.Vol. 33-34, 2015, page: 123-128

Measuring Soil Respiration with a Gas Chromatograph

Measuring Soil Respiration with a Gas Chromatograph

Exotic Asian pheretimoid earthworms (Amynthas spp., Metaphire spp.): Potential for colonisation of south-eastern Canada and effects on forest ecosystems

Exotic species invasions are among the most significant global-scale problems caused by human activities. They can seriously threaten the conservation of biological diversity and of natural resources. Exotic European earthworms have been colonizing forest ecosystems in northeastern United States and southern Canada since the European settlement. By comparison, Asian earthworms began colonizing forests in the northeastern United States more recently. Since Asian species have biological traits compatible with a greater potential for colonization and disturbance than some European species, apprehension is growing about their dispersal into new territories. Here we review the extent of the current northern range of Asian earthworms in northeastern North America, the factors facilitating or limiting their propagation and colonization, and the potential effects of their invasion on forest ecosystems. Data compilation shows that Asian earthworms are present in all northeastern American states. So far, only one mention has been reported in Canada. Data confirm that their distribution has now reached the Canadian border, particularly along the Michigan–Ontario, New York–Ontario, Maine–New Brunswick, and Vermont–Québec frontiers. Studies report that the presence of Asian earthworms is strongly associated with human activities such as horticulture, vermicomposting, and the use of worms as fish bait. Some climatic (temperature, soil moisture) and edaphic (soil pH) factors may also influence their distribution. Controlling their dispersal at the source is essential to limiting their spread, as there is currently no effective way to eradicate established earthworm populations without unacceptable nontarget effects. Proposed management options in the United States include the prohibition of fish bait disposal and better management of the international trade of horticultural goods, commercial nurseries, and vermicomposting industries. We conclude that although regulations and awareness may delay their expansion, Asian earthworms are likely to spread further north into Canada. They are expected to cause important changes to biodiversity and dynamics of the newly invaded forest ecosystems.

Effects of agricultural management practices on soil quality: A review of long-term experiments for Europe and China

In this paper we present effects of four paired agricultural management practices (organic matter (OM) addition versus no organic matter input, no-tillage (NT) versus conventional tillage, crop rotation versus monoculture, and organic agriculture versus conventional agriculture) on five key soil quality indicators, i.e., soil organic matter (SOM) content, pH, aggregate stability, earthworms (numbers) and crop yield. We have considered organic matter addition, no-tillage, crop rotation and organic agriculture as “promising practices”; no organic matter input, conventional tillage, monoculture and conventional farming were taken as the respective references or “standard practice” (baseline). Relative effects were analysed through indicator response ratio (RR) under each paired practice. For this we considered data of 30 long-term experiments collected from 13 case study sites in Europe and China as collated in the framework of the EU-China funded iSQAPER project. These were complemented with data from 42 long-term experiments across China and 402 observations of long-term trials published in the literature. Out of these, we only considered experiments covering at least five years. The results show that OM addition favourably affected all the indicators under consideration. The most favourable effect was reported on earthworm numbers, followed by yield, SOM content and soil aggregate stability. For pH, effects depended on soil type; OM input favourably affected the pH of acidic soils, whereas no clear trend was observed under NT. NT generally led to increased aggregate stability and greater SOM content in upper soil horizons. However, the magnitude of the relative effects varied, e.g. with soil texture. No-tillage practices enhanced earthworm populations, but not where herbicides or pesticides were applied to combat weeds and pests. Overall, in this review, yield slightly decreased under NT. Crop rotation had a positive effect on SOM content and yield; rotation with ley very positively influenced earthworms’ numbers. Overall, crop rotation had little impact on soil pH and aggregate stability − depending on the type of intercrop; alternatively, rotation of arable crops only resulted in adverse effects. A clear positive trend was observed for earthworm abundance under organic agriculture. Further, organic agriculture generally resulted in increased aggregate stability and greater SOM content. Overall, no clear trend was found for pH; a decrease in yield was observed under organic agriculture in this review.

Effects of composted green waste on soil quality and tree growth on a reclaimed landfill site

The addition of composted green waste (CGW) into soil-forming materials during land reclamation can benefit tree growth by improvement of soil properties and provide an effective waste management solution. CGW addition may also assist the establishment of earthworm populations, which in turn aid soil development through their burrowing and feeding activities. An experiment was set up on a reclaimed landfill site, to measure the effects of CGW addition on soil physical and chemical quality and subsequently on the survival and growth of two tree species (Acer platanoides and Alnus cordata). A further objective was to measure the influence of earthworm (Aporrectodea longa) addition on the above. CGW addition led to significantly greater A. cordata growth (height and diameter) and increased survival rate. No benefits from CGW addition were observed on A. platanoides growth or survival, although this is likely due to soil drought conditions during establishment. CGW addition significantly increased levels of organic carbon and essential plant macro-nutrients in the reclaimed soil. Soil pH rose slightly across all treatments, with highest final pH under the control treatment. Earthworm inoculation, as used, was unsuccessful at increasing population density of A. longa. This experiment showed that CGW application can effectively improve tree establishment and soil quality on reclaimed landfill; however tree species selection is an important consideration, based on individual species tolerance and sensitivity to certain soil conditions. These findings will be informative to decisions on soil amendment and afforestation activities on similar reclaimed landfill sites.

Feedstock composition influences vermicomposting performance of Dichogaster annae relative to Eudrilus eugeniae and Perionyx excavatus.

Carbon to nitrogen (C/N) ratio influences substrate combinations and earthworm performance in vermicomposting systems. To elucidate these factor effects, a comparative evaluation of species, C/N ratio combined with feed rate, was conducted on three local earthworm species: Perionyx excavatus, Eudrilus eugeniae, and Dichogaster annae. Earthworms were stocked at similar densities and fed shredded paper (SP), cattle manure (CM), and lawn clippings (LC) combined to form C/N ratios of 28, 36, and 53. Earthworms were fed at rates of 1, 1.25, and 2g feed (dry wt.)/g worm/day for a period of 8weeks. Percent vermiconversion, earthworm adult and juvenile biomass, and vermicast quality were measured. Vermicast production was significantly affected by the combination of C/N ratio and feed rate and varied among species. All treatment combinations resulted in > 70% conversion, except E. eugenaie fed at the medium rate. Vermiconversion increased for P. excavatus and D. annae with increasing C/N ratio but decreased with increasing the feed rate. Vermicast EC, pH, and C/N ratio was strongly affected by species, relative to other experimental factors. D. annae showed the greatest change in biomass, which peaked at the highest feed rate and lowest C/N ratio. Average adult biomass decreased for P. excavatus with increasing feed rate, while differences were nonsignificant for E. eugenaie and D. annae. Significant increases in average juvenile biomass were only evident for D. annae in response to increasing feed rates. Feed rate had a greater influence on earthworm population dynamics and vermicast quality compared to initial feedstock C/N ratio.

EGrowth: A global database on intraspecific body growth variability in earthworm

Earthworms play a key role in soil and ecosystem functioning. Predicting their abundance and spatial distribution is required to understand their ecological role. There is growing evidence that mechanistic models of earthworm population dynamics are promising tools to tackle this issue. However, this approach requires a fair amount of data because it explicitly integrates the three fundamental biological processes: growth, reproduction and mortality. Hitherto, the lack of comprehensive databases on life history parameters related to these three processes hampered the widespread development of mechanistic earthworm population dynamics models. As a consequence, predicting earthworm abundance in a variety of conditions across species is still difficult.The clear bottleneck for making progress is the lack of databases on the intraspecific variability of earthworm life history traits in response to environmental conditions. Data related to body growth and body size are critical because body size largely determines reproduction and mortality rates. Body growth is therefore the backbone of mechanistic models of earthworm population dynamics.Here I present EGrowth, the first comprehensive database on intraspecific variability of earthworm body growth in relation to environmental conditions. The EGrowth database contains 1073 growth curves of 51 species of earthworms, representing 16002 measures of body mass. It covers publications on earthworm body size from 1900 to 2016. The environmental conditions in which the growth curves were produced are also reported. The database is open access and can be browsed from a graphical user interface. EGrowth will be updated regularly in the future as new studies are published. I propose a standardized framework for reporting future data on body growth of earthworms.

Corn residue inputs influence earthworm population dynamics in a no-till corn-soybean rotation

Temporal dynamics of earthworm populations in temperate agroecosystems are related to climatic and edaphic conditions, agricultural management and crop residue inputs. The amount of crop residue present and its suitability as a food resource for earthworms changes as the material decomposes. A readily-decomposable crop residue (low C:N ratio, low lignin content) may be a transient food resource for earthworms, whereas residues that decompose more slowly could be a persistent food resource to sustain the earthworm populations. Chemical composition of the crop residue and the particulate organic matter (POM) content in soil, a measure of the partially-decomposed residues, are indicators of the food resources for earthworms. The objective of this study was to determine how the quantity and chemistry of crop residues, and the soil POM content, were related to earthworm population dynamics during a two-year field experiment in no-till corn-soybean rotations. The high residue treatment provided an additional 3–5 Mg ha−1 y−1 in corn residue, compared to the low residue treatment. As hypothesized, earthworm abundance and biomass were strongly affected by the quantity of crop residues left in the agroecosystem after harvest. Greater corn residue inputs in the high residue treatment supported an earthworm community that had similar species composition and age structure, but was nearly twice as large as the earthworm community in the low residue treatment. Soybean residue appeared to be a transient food resource for earthworm populations in the field. Earthworm abundance and biomass were related to the amount of surface residue present, but were not correlated to the chemical composition of crop residue and the soil POM content during this two-year study. Under field conditions, earthworm populations respond to the quantity of residues present as a food resource rather than the chemical composition of the residue.

Earthworm-induced shifts in microbial diversity in soils with rare versus established invasive earthworm populations.

European earthworms have colonised many parts of Australia, although their impact on soil microbial communities remains largely uncharacterised. An experiment was conducted to contrast the responses to Aporrectodea trapezoides introduction between soils from sites with established (Talmo, 64 A. trapezoides m-2) and rare (Glenrock, 0.6 A. trapezoides m-2) A. trapezoides populations. Our hypothesis was that earthworm introduction would lead to similar changes in bacterial communities in both soils. The effects of earthworm introduction (earthworm activity and cadaver decomposition) did not lead to a convergence of bacterial community composition between the two soils. However, in both soils, the Firmicutes decreased in abundance and a common set of bacteria responded positively to earthworms. The increase in the abundance of Flavobacterium, Chitinophagaceae, Rhodocyclaceae and Sphingobacteriales were consistent with previous studies. Evidence for possible soil resistance to earthworms was observed, with lower earthworm survival in Glenrock microcosms coinciding with A. trapezoides rarity in this site, lower soil organic matter and clay content and differences in the diversity and abundance of potential earthworm mutualist bacteria. These results suggest that while the impacts of earthworms vary between different soils, the consistent response of some bacteria may aid in predicting the impacts of earthworms on soil ecosystems.

Rye cover crop increases earthworm populations and reduces losses of broadcast, fall-applied, fertilizers in surface runoff

Corn (Zea mays L.) silage and soybean [Glycine max (L.) Merr.] rotations in the US Upper Midwest leave minimal amounts of surface residues, which can contribute to soil degradation, increased surface runoff, and reduced water quality. Planting cover crops after harvest can reduce these concerns, but their effectiveness in reducing nutrient losses in surface runoff shortly after fall planting and fertilization has not been thoroughly investigated. Therefore, we applied 65 mm of simulated rainfall in 60 min to five replicate, 1.5 by 3.0 m, field plots in a no-till, corn silage-soybean rotation into which a rye (Secale cereale L.) cover crop was planted for 14 consecutive years and to five replicate plots with no cover crop history. Natural slope of the plots ranged from 0.1 to 2.7%. The study was conducted in October 2014, about one month after corn silage harvest and rye planting and ∼1 h after broadcast application of monoammonium phosphate and potassium chloride fertilizers. The living rye cover crop significantly (P ≤ 0.05) delayed surface runoff by 5.7 min and decreased total runoff by 65% compared to plots with no cover crop. This resulted in a significant 68% reduction in sediment loss and even greater significant reductions in fertilizer nutrient losses (i.e., NH4-N - 86%; total P - 83%; total dissolved P - 84%; K - 91%). Earthworm population and biomass, measured using electrical extraction shortly after the rainfall simulations, were 1.2 and 1.4 times greater in cover crop plots than in no cover plots and 3.2 and 2.5 times greater the following spring. Our results suggested that a living cover crop and their long-term usage can contribute to improvements in soil structure and increased earthworm populations that can substantially reduce sediment and nutrient losses in surface runoff due to a severe storm shortly after post-harvest broadcast application of fertilizer.

Forecasting tillage and soil warming effects on earthworm populations

Abstract Healthy soils are crucial for sustainable food production, but tillage limits the biological regulation of essential ecosystem services. Better understanding of the mechanisms driving management effects on soil ecosystem engineers is needed to support sustainable management under environmental change. This paper presents the Energy–Environment–Earthworm (EEEworm) model, a mechanistic individual‐based model of Lumbricus terrestris populations. Lumbricus terrestris is a dominant earthworm species in undisturbed habitats and is closely associated with numerous ecosystem services such as water flow regulation, soil structure and crop production. In reduced tillage agriculture, a decline in mechanical disturbance allows for L. terrestris proliferation, whilst the activities of L. terrestris can replace many of the soil functions provided by tillage. Extensive EEEworm validation with eight published studies (average R2 = .84) demonstrates a mechanistic approach which can extrapolate between diverse soil, management and weather conditions. EEEworm simulation experiments elucidate that a combination of direct and indirect tillage effects leads to population declines in tilled fields, with litter removal from the soil surface being the main driver. We investigate the effects of different tillage intensities under historical and projected soil warming conditions and find that future warmer and drier soils in our simulation exacerbate the effects of deep ploughing on L. terrestris population declines. These effects result from warmer and drier soil conditions increasing individual metabolic rates and tillage reducing food availability to meet energy demands. Synthesis and applications. Pre‐emptive strategies to mitigate climate change impacts on soil health in agroecosystems should focus on decreasing tillage intensity and retention of crop residues following tillage. Energy–Environment–Earthworm (EEEworm) has the potential to benefit land managers, policy makers, risk assessors and regulators by providing a tool to forecast how soil systems respond to combinations of land management and environmental change. To allow better cost–benefit analysis of contrasting land management systems, a future aim of mechanistic models like EEEworm is to incorporate the links between earthworm populations, soil functions and ecosystem services.

Winter hatching in New England populations of invasive pheretimoid earthworms Amynthas agrestis and Amynthas tokioensis: a limit on population growth, or aid in peripheral expansion?

Some Asian megascolecid earthworms, e.g. Amynthas agrestis and Amynthas tokioensis, are highly invasive and have only recently been reported from natural ecosystems in the northeastern USA. There, they are annual earthworms that survive the winter as cocoons (an egg in a tough covering). Hatching occurs in mid-April when temperatures rise consistently above 10 °C. In some years, winter temperatures also reach 10 °C during short warming episodes, but hatchlings then are likely to die when temperatures drop again. To test this hypothesis, soil was collected on 7 sampling dates during January–May 2016 at one site in the Champlain Valley, Vermont and extracted for the cocoons. Both hatched and unhatched cocoons were enumerated and identified to species by both size and sequencing of the mitochondrial cytochrome c oxidase I gene (COI). A regression model on the number of unhatched cocoons over time predicted that ~ a quarter (A. agrestis) and ~ a third (A. tokioensis) would hatch before mid-May; no hatchlings were observed. Thus, hatching during warming periods in winter seemingly resulted in high mortality. Such winter hatching, and loss, may increase with climate warming in the region because winter warming periods should become more common. Climate warming could therefore reduce ability of the invasive earthworms to persist in northern habitats. Conversely, rapid hatching when the soil warms in spring could have an ecological benefit by allowing opportunities to expand at the thermal edge of the range as the climate continues to warm.

Distribution and diversity of earthworm (Annelida, Clitellata)populations across four land use types in northern Cameroon

Earthworms are present in all types of soil. Changes in land use influence populations of earthworms. However, information on the dynamics of earthworm populations in northern Cameroon is not available. This paper highlights the research carried out on the abundance, biomass, and diversity of earthworm populations throughout four types of land use in northern Cameroon. Earthworms were sampled throughout the rainy season in three regions, across pastures, woody savannahs, grass savannahs, and fields, using formaldehyde and hand sorting. Earthworms of the woody savannah and pasture have a high mean density (63 and 45 individuals/m2, respectively) and biomass (25.2 and 22 g/m2, respectively). Region rather than land use had a significant effect (P = 0.031) on earthworm diversity. The increase in earthworm abundance in woody savannah and pasture is certainly due to the modification of the soil microclimate and litter by ligneous plants, and to the input of cow dung in pastures, both of which improve the quality and quantity of the organic matter brought to the soil. This research provides insight into the patterns of earthworm populations in northern Cameroon and the need to implement adequate use and management strategies for the maintenance of these soil organisms that provide major ecosystem services.

Changes in Vegetation and Earthworm Populations under Free Grazing European Bison (Bison bonasus) in Broad-Leaved Forests of the Kaluzhskie Zaseki State Nature Reserve

This paper studies the impact of a free-ranging bison population on the vegetation and soil fauna in spatially adjacent biotopes (meadow-transition zone-surrounding forest) in the Kaluzhskie Zaseki State Nature Reserve. It is noted that bison maintains meadows in the absence of haymaking. Analysis of phytosociological releves shows that the forest vegetation has been significantly transformed by bison over 10–15 years, as evident from (1) differences in the ecological-coenotic structure of the vegetation in the different biotopes, (2) a larger ecological-coenotic diversity of communities in the transition zones in comparison with surrounding forests, and (3) an increase in the participation of nitrophilous species in the vegetation. A fairly high earthworm species diversity (a total of seven species in the biotopes) is found; Aporrectodea caliginosa dominates in the earthworm density and biomass. The total earthworm density and biomass became lower in the transition zone than in neighboring forests and meadows, and the differences in earthworm density between the transition zone and the meadows were statistically significant.

EARTHWORM POPULATION AT THE POST COAL MINING FIELD IN EAST KALIMANTAN, INDONESIA

Coal mining activities in Indonesia result in heavy soil degradation and significant decrease in earthworm population. This study aims to explore the population of earthworms at different ages of the plant in the post coal mining rehabilitation areas. PT. Kideco Jaya Agung, East Kalimantan. In this study, 5 samples (30 cm x 30 cm, 20 cm depth) of soil were collected from 5 rehabilitation sites. Sites were selected based on age after rehabilitation: 2, 4, 6, 8 and 10 years after replanting, and sampled with 20 m distances between samples to determine earthworm population. The depth of litter layer and species of plants were also recorded at each site. Chi square analysis was conducted to determine the significance of earthworm density in rehabilitation sites at different ages, while correlation analysis was conducted to determine correlation between litter thickness and the number of earthworms found in the research sites. Only 2 species of earthworms were found in this study; their abundance increased increased in line with the age of rehabilitation areas. The number of earthworms (density) at 10 years after rehabilitation was almost similar to that in the natural forests. In conclusion, planting tree species producing significant amount of litter might stimulate the earthworm community and initiate succession. It might also take more than 10 years to return to the previous state for the earthworms in terms of density after land rehabilitation of the coal mining areas is conducted.

The effect of urea on epigeic earthworm species (Eisenia foetida)

Long W, Ansari A, Seecharran D. 2017. The effect of urea on epigeic earthworm species (Eisenia foetida). Cell Biol Dev 1: 46-50. The use of chemical fertilizers in intensive agriculture has no doubt increased crop production but it has resulted in adverse effect on soil properties over a long period of time. The effects are clearly seen in the soil environment including the soil organisms living in that ecosystem. This study was conducted to determine effects of Urea on epigeic earthworm species (Eisenia foetida) in clay soil. A total of five doses of Urea were used i.e 50 mg/kg, 100 mg/kg, 150 mg/kg, 200 mg/kg and 250mg. They were labelled as T1, T2, T3, T4, and T5, respectively. A control group was also set up and the treatment groups were replicated three times. The results indicated that the addition of urea affected the soil chemical properties in treatments inoculated with earthworms (Eisenia foetida). The adult earthworm population was 70% in control when compared to different treatment dosage of Urea 50 mg/kg (T1)-85%, 100 mg/kg (T2)-66.67%, 150 mg/kg (T3)- 68.34%, 200 mg/kg (T4)- 86.67% and 250 mg/kg (T5)- 51.67%. The percentage mortality minimum in treatment T4 and T1 whereas it was maximum in treatment T5 (48%). 250 mg/kg was the most toxic dose of Urea in the soil inoculated with earthworms. The results were significant at p=0.05.