Earthworm Biomass Research Articles

Effects of residue types and plastic mulch on earthworm aporrectodea trapezoides (Duges, 1828) within mesocosms at a salt-affected soil

ABSTRACT Earthworm colonization is an effective management practice to improve soil conditions. In a salt-affected reclamation soil, we conducted a mesocosm experiment to test the effects of organic residue application (no organic residues, clover residues or sheep manure) and plastic film (mulching or no mulching) on the survival, biomass and production of earthworms (Aporrectodea trapezoides (Duges, 1828)). Results showed that application of organic residues yielded a higher survival rate (37–100%) and biomass (0.43–0.98 g) of earthworms than the treatments without organic residue, regardless of plastic mulch. Moreover, the application of sheep manure significantly increased earthworm survival (58%) and biomass (160%) compared to the application of clover residues, which may be due to high soil available resources and nutrients in the soils with sheep manure. No significant differences (p = 0.26) in the survival rate (37–100% and 47–82%) or biomass of A. trapezoides were observed between the mulch and no-mulch treatments. This study indicated that animal manure out-performed clover residues in promoting the growth and survival of A. trapezoides in a reclaimed, salt-affected soil. Moreover, plastic film mulching improved soil moisture, but had no effect on the survival and biomass of A. trapezoides.

Impact of crop establishment and residue management on soil properties and productivity in rice‐fallow ecosystems in India

AbstractThe degradation of agricultural land, both chemical and biological, is a big concern all over the world. Crop cultivation practices that are distinctive to each location have negative consequences for agricultural production. Therefore, there is an urgent need for better crop and soil management techniques. This experiment was conducted for 5 years (2016–2020) to identify the best crop establishment‐cum‐residue management (CERM) practices and suitable crops for succession after the rice harvest in rice‐fallow ecosystems of India. Experimentation was conducted in the split‐plot design and each treatment was replicated thrice, having CERM in main‐plot and post‐rainy season/winter crops in sub‐plot. All the CERM treatments had two variants, with crop residue (R+) and without crop residue (R−). Rice yields were markedly higher (19.1%–32.2%) in transplanted puddled rice with residue (TPR‐R+) over conventional‐till direct seeded rice (CTDSR) and zero‐till DSR (ZTDSR) treatments. However, TPR adversely impacted the performance of all the post‐rainy pulses/oilseed crops. Post‐rainy season crop yields under ZTDSR/CTDSR were 14.9%–45.8% higher leading to higher system productivity as compared to TPR. ZTDSR with residue retention showed higher soil aggregation. The practice of ZTDSR increased the soil dehydrogenase activity (46.2%), urease activity (29.8%), soil microbial biomass carbon (65.4), and fluorescein diacetate activity (9.0%) in the crop root zone with 3.3‐ and 4.47‐times higher earthworm population and earthworm biomass, respectively. The rice‐pulse system showed 1.74‐times more earthworm population over rice‐oilseed sequences. Total soil organic carbon (SOC) stock in ZTDSR was 21.8% higher over TPR in 0–45 cm soil profile. Thus, the adoption of ZTDSR practices and diversification of rice‐fallows with pulses crops is recommended for enhancing the crop productivity, increasing SOC stock, and improving soil biological properties in the rice‐fallow ecosystems of India.

Municipal solid waste as the prospective substrate for earthworm Eisenia fetida to convert waste into manure

Organic wastes or bio-wastes are not “waste” but prospective bio-resources. Management of bio-waste by technical methods has become a burning issue in the present time. In the present study cow dung (CD), Mango litter (ML) and Municipal solid waste (MSW) was treated with earthworm Eisenia fetida in different mixture ratios of the substrate. Waste was converted into organic manure along with increase in biomass and number of earthworms. This is supposed to be due to the rich concentration of OC, N, P and microbial population.

Effects of one-dimensional nanomaterial polyaniline nanorods on earthworm biomarkers and soil enzymes.

Polyaniline nanorods (PANRs) are typical one-dimensional nanomaterials (1D NMs), which are widely used in medicine, batteries and water treatment, etc. Applications of PANRs will eventually enter the soil environment, but their ecotoxicity has been barely reported. Therefore, we measured earthworm biomass, earthworm biomarkers and soil enzymes to investigate the ecotoxicity of PANRs. The result of positive and increasing growth inhibition rates (GIR) showed that PANRs inhibited earthworm growth. As for earthworm biomarkers, PANRs caused a decrease in protein content, indicating that PANRs stress would increase earthworm energy consumption. Except for the 7th day, the activities of SOD, CAT and POD consistently increased, suggesting that PANRs activated the earthworm antioxidant system. The continually augment of MDA content indicated that PANRs stress would cause earthworm lipid damage. Na+-K+-ATPase increased with an excellent dose-time relationship. Differently, cellulase and AChE activities promoted at low concentrations and inhibited at high concentrations. The positive and dose-dependent IBRv2 indicated that the higher the concentrations of PANRs, the greater the ecotoxicity to earthworms. PANRs inhibited the soil enzyme activities such as sucrase, neutral phosphatase, protease and urease, while induced catalase activity in a dose-dependent manner. Earthworm addition reduced catalase activity by 10.74-29.99%, but improved other soil enzymes activities, demonstrating that earthworms played a positive role in regulating soil enzyme activity. GMean and T-SQI consistently increased due to earthworm activity, meaning a higher soil microbial functional diversity. Generally, this study provided data support for future PANRs toxicity studies, but their toxicity mechanisms still need to be further studied.

Litter layer and earthworms as an indicator of coffee production in the coffee and pine based agroforestry system

Critical support for successful coffee-based agroforestry production is the amount of litter input and the activity of macro-organisms. The purpose of this study was to analyze the relationship between the amount of litter on the soil surface, the population of earthworms, and the growth and production of coffee. The research was conducted between June 2019 and March 2020 at the Universitas Brawijaya Forest, East Java, Indonesia. For the coffee plants, a proportional random sampling method was used to capture the range of plant sizes within the study location. The range of diameters at breast height (DBH) recorded were divided into ten decils and four replicates within each decil. For each plant, DBH was transformed into tree biomass and fresh coffee bean weight was also measured. Litter weight and depth were measured using a 50 x 50 cm quadrat frame. A sampling of earthworms used the TSBF monolith method. There was a positive relationship between litter thickness, litter weight, the number of earthworms, and earthworm biomass against the dry weight coffee bean, while the four variables have no significant relationship with coffee tree biomass. We concluded that litter layer and earthworm biomass can be used as a simple indicator of coffee production.

Population characteristics and influencing factors of terrestrial earthworms in Qinling Mountains

Earthworms can have an important effect on a variety of processes that determine soil fertility and play a very important role in natural ecosystems. The biomass and density of earthworms in 4 different land utilize types in the Qinling mountains were investigated using the wet funnel method. The relationship between the characteristics of earthworm populations characteristics and environmental factors were analysed, and the significant differences in soil earthworm density (P < 0.05) and fresh weight (P < 0.05) were discovered under different land utilize types, and all showed the highest value in orchard land, followed by woodland and grassland, in addition, the lowest was discovered in cultivated land. In addition, Pearson correlation analysis indicate that soil earthworm population characteristics was strongly negatively correlated with soil ammonium nitrogen (NH4+-N), and strongly positively correlated with fine root biomass. The clarified relationship between earthworm population characteristics and soil physical and chemical properties will help qualitatively predict and evaluate the ecological functions of terrestrial earthworms in Qinling mountains.

Comparative Study on Effect of Pesticides and Vermicompost on the Growth of Eisenia foetida

Earthworms are important soil invertebrates and play an important role in improving soil quality. They act as nature´s best fertilizers and have beneficial role in the process of vermicomposting which is very useful in crop production. The Indiscrete use of chemical fertilizers and pesticides poses a threat to soil quality, crop production and also hampered the growth of earthworms. In the present study the impact of pesticides and vermicompost in potato crops field and on Eisenia foetida was evaluated. The study aimed to understand the effect of chemical and biological fertilizers on the life table attributes of earthworm, Eisenia foetida. Laboratory adapted Eisenia foetida were reared on artificial soil supplemented with chemical fertilizers and vermicompost. Changes in number and biomass of Eisenia foetida were monitored four times in various applications of pesticides and in vermicompost. Four pesticides that are commonly used in potato crops are Chlorpyrifos, Malathion, Carbofuran and Cypermethrin. Thus, the negative impact of these pesticides on Eisenia foetida and Potato crops has been reported when compared to the control (Vermicompost). The effect of Pesticides was noted in following order: Chlorpyrifos ˃ Malathion ˃ Cabofuran ˃ Cypermethrin. Application of Chlorpyrifos to the potato crop field harboring earthworms reduced the number of earthworms from 200 in the control group to 20 after 60 days of the application. The effect was more pronounced on the total biomass of the culture owing to the high toxicity of Chlorpyrifos. The Pesticides treatment decreased the percent survival of the earthworms by 70% and 40%, respectively. The number and biomass of Earthworm decreased on increasing the application of pesticides thus, reduces crop production. On the other hand, the vermicompost had a positive effect on the earthworm’s biology.

Vermicomposting of cow manure: Effect of time on earthworm biomass and chemical, physical, and biological properties of vermicompost

Vermicomposting is a biological process for efficient cattle manure treatment, but the vermicomposting time determines the quality of the vermicompost. The objective of this study was to evaluate the effect of cattle manure vermicomposting time on earthworm biomass and the changes in physical, chemical, and biological in properties of the vermicompost. The cattle manure was inoculated with Eisenia andrei earthworms and conducted vermicomposting for 0, 15, 30, 45, 60, and 120 days. The analysis of 44 chemical, physical, and biological properties allowed the vermicomposting process to be divided into initial (<45 days) and final (45–120 days) phases. The initial phase was characterized by high microbial activity and the final by high physical–chemical transformation of the vermicompost and an increase in earthworm density. The organic matter aromaticity increased until the 45th day, subsequently decreasing. Although 30 d of vermicompost are sufficient to obtain a high-quality organic fertilizer, 120 d are necessary for producing matrices.

Introduction of mechanized vermicomposting for utilization of vegetable waste of horticultural farms

The article deals with the expediency of using vermicomposting technologies in horticulture. Recommendations for the introduction of vermiculture technology in horticulture have been developed. Before the introduction of vermiculture technology, it is necessary to prepare the substrate. It is recommended to use the following composition of the substrate: plant tops; sawdust; tree leaves; peat, lime (up to 2 % by weight of the substrate). The substrate must undergo fermentation for at least 3 months, 3–5 months in winter. Storage of the substrate can last 8–10 months at a humidity of 70–80 %. The readiness of the substrate for consumption is determined by the ratio of carbon to nitrogen, which should be about 20. Acidity 6–8 pN. Selection of raw compost is carried out 2 times a year. Then it is used as fertilizer or sent for processing. If you process the shredded branches, the full selection can be done in 1.5 years. The dependence for determining the required biomass of earthworms on the productivity of vermigulture to process the established mass of substrate for the year of vermiculture has been established. It is determined that to create a vermigree with a capacity of 100 tons of substrate/year requires 10 kg of earthworm biomass, 500 tons of substrate/year – 45 kg, 1000 tons of substrate/year – 91 kg, 1500 tons of substrate/year – 137 kg, 2000 tons substrate/year – 182 kg. The given methodical bases of mechanized vermig farms give the chance to carry out the calculations necessary for processing of waste of vegetable origin in garden and park farms and reception of biohumus and biomass of earthworms. The introduction of such technology will allow the safe disposal of waste of plant origin of horticulture: tree leaves, waste from flower production, etc. to obtain a highly effective fertilizer – compost. Key words: vermicomposting, earthworms, compost, equipment, organic waste.

Veterinary antibiotics can reduce crop yields by modifying soil bacterial community and earthworm population in agro-ecosystems

Veterinary antibiotics are intensively and widely used in animal farming to treat or prevent diseases, as well as improve growth rate and feed efficiency. Animal manure is an important reservoir of veterinary antibiotics due to their high excretion rates, and thus manure application has been a critical source of veterinary antibiotics in agro-ecosystems. However, how veterinary antibiotics affect agroecosystem functions is still unclearly understood. In this study, we evaluated the effects of veterinary antibiotics on soil bacteria and earthworms in agricultural land with long-term manure application. The potential mechanisms of antibiotic-induced changes in crop yields were also revealed. The results showed that the increasing prevalence of veterinary antibiotics in agro-ecosystems inhibited earthworm abundance and bacterial diversity, and then decreased the bioavailability of soil nutrients. Furthermore, high-dose exposure to veterinary antibiotics improved the abundance of plant pathogenic bacteria. Analysis indicated that veterinary antibiotics played an important underlying role in driving the negative effects on peanut grain yields via disturbing microbe- and earthworm-mediated soil available nutrient contents. The direct toxicity effects of antibiotics on peanut relative yields were stronger than their indirect mediating effects. Additionally, the tradeoffs between antibiotics and agroecosystem functions increased at low exposure levels and then decreased at high exposure levels, which indicated the effects of antibiotics on agroecosystem functions were dose-dependent, except for earthworm biomass. Antibiotic contamination which will impose threats to agricultural sustainability was highlighted and should be paid more attention.

Enhanced growth of ginger plants by an eco- friendly nitrogen-fixing Pseudomonas protegens inoculant in glasshouse fields.

BACKGROUNDExcessive nitrogen (N) fertilization in glasshouse fields greatly increases N loss and fossil‐fuel energy consumption resulting in serious environmental risks. Microbial inoculants are strongly emerging as potential alternatives to agrochemicals and offer an eco‐friendly fertilization strategy to reduce our dependence on synthetic chemical fertilizers. Effects of a N‐fixing strain Pseudomonas protegens CHA0‐ΔretS‐nif on ginger plant growth, yield, and nutrient uptake, and on earthworm biomass and the microbial community were investigated in glasshouse fields in Shandong Province, northern China.RESULTSApplication of CHA0‐ΔretS‐nif could promote ginger plant development, and significantly increased rhizome yields, by 12.93% and 7.09%, respectively, when compared to uninoculated plants and plants treated with the wild‐type bacterial strain. Inoculation of CHA0‐ΔretS‐nif had little impact on plant phosphorus (P) acquisition, whereas it was associated with enhanced N and potassium (K) acquisition by ginger plants. Moreover, inoculation of CHA0‐ΔretS‐nif had positive effects on the bacteria population size and the number of earthworms in the rhizosphere. Similar enhanced performances were also found in CHA0‐ΔretS‐nif‐inoculated ginger plants even when the N‐fertilizer application rate was reduced by 15%. A chemical N input of 573.8 kg ha−1 with a ginger rhizome yield of 1.31 × 105 kg ha−1 was feasible.CONCLUSIONSThe combined application of CHA0‐ΔretS‐nif and a reduced level of N‐fertilizers can be employed in glasshouse ginger production for the purpose of achieving high yields while at the same time reducing the inorganic‐N pollution from traditional farming practices. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Field application of pure polyethylene microplastic has no significant short-term effect on soil biological quality and function

Plastics are now widespread in the natural environment. Due to their size, microplastics (MPs; defined as particles <5 mm) in particular, have the potential to cause damage and harm to organisms and may lead to a potential loss of ecosystem services. Research has demonstrated the significant impact of MPs on aquatic systems; however, little is known about their effects on the terrestrial environment, particularly within agroecosystems, the cornerstone of global food production. Soil biology is highly responsive to environmental perturbation and change. Hereby, we investigated the effect of pure low-density polyethylene (LDPE) MP loading (0, 100, 1000, or 10000 kg ha−1) on soil and plant biological health in a field environment over a cropping season. Our results showed that MP loading had no significant effect (p > 0.05) on the soil bacterial community diversity (as measured by amplicon sequencing of bacterial 16S rRNA gene), the size and structure of the PLFA-derived soil microbial community, or the abundance and biomass of earthworms. In addition, metabolomic profiling revealed no dose-dependent effect of MP loading on soil biogenic amine concentrations. The growth and yield of wheat plants (Triticum aestivum L., cv. Mulika) were also unaffected by MP dose, even at extremely high (≥1000 kg ha−1) loading levels. Nitrogen (N) cycling gene abundance before and after N fertiliser application on the MP loaded experimental plots showed relatively little change, although further experimentation is suggested, with similar trends evident for soil nitrous oxide (N2O) flux. Overall, we illustrate that MPs themselves may not pose a significant problem in the short term (days to months), due to their recalcitrant nature. We also emphasise that most MPs in the environment are not pure or uncontaminated, containing additives (e.g. plasticisers, pigments and stabilisers) that are generally not chemically bound to the plastic polymer and may be prone to leaching into the soil matrix. Understanding the effect of additives on soil biology as well as the longer-term (years to decades) impact of MPs on soil biological and ecological health in the field environment is recommended.

WORM BIOMASS AND VERMICOMPOST PRODUCTION BY THE EPIGEIC EARTHWORM, PERIONYX EXCAVATUS BY USING DIFFERENT ORGANIC WASTES

As the epigeic earthworms are known to be efcient and potential biodegrades and nutrient releasers, tolerant to wide range of ecological disturbances, aids in litter communication and efcient decomposers. Therefore, the present study was undertaken to nd out the inuence of various organic wastes (such as False Ashoka waste-FAW (Polyalthia longifolia), Parthenium wastePW (Parthenium hysterophorus), Cotton residue waste-CRW (Gossypium), Lawn grass waste-LGW (Agrostis) and Cattle manure-CM) on the production of worm biomass and vermicompost by the epigeic earthworm, Perionyx excavatus along with control compost experiments without worms (in triplicates) to know the potentiality of this worm species in processing of various organic wastes for the production of worm biomass as vermiprotein and vermicompost as biofertilizer. Both compost and vermicompost experimental pots were terminated after 35 and 70 days time intervals. Observations were made with respect to number of old and new adult worms, new sub-clitellates, juveniles, cocoons with their weight were noted to determine the total worm biomass (Gross biomass), biomass ratio (WBR) and Fold Increase in Worm Number (FIWN). Percent compost and vermicompost produced out of different organic waste were also calculated at the end of each experiment at35 and 70 days. The results of the present study revealed that the biomass of Perionyx excavatus such as Gross worm biomass (GWB), Worm biomass ratio (WBR) and Fold increase in worm number (FIWN) increased from 35days to 70 days time intervals in all the organic wastes (FAW, PW, CRW, LGW and CM). It was maximum in CM and minimum in FAW among all the organic wastes. There is a signicant variation was noticed in worm biomass production (GWB, WBR, and FIWN) among and between all the organic wastes except between few organic wastes at 35 and 70 days time intervals. The vermicompost production was more as compared to normal compost in all the organic wastes. Further, both compost and vermicompost production were more in CM followed by LGW, CRW, PW and minimum in FAW among all organic wastes. The signicant difference was also observed in the production of compost and vermicompost among and between different organic wastes except between few organic wastes at different time intervals. Based on the results, it can be concluded that the earthworm, Perionyx excavatus is an efcient epigeic earthworm species, effectively used in vermicomposting for the production of vermicompost and as well as in vermifarming in the production of worm biomass as vermiprotein. Further, earthworm biomass, compost and vermicompost production primarily depends on nature of organic wastes and secondly on the potentiality of earthworm species used in the experimental studies.

Formulation of Organic Wastes as Growth Media for Cultivation of Earthworm Nutrient-Rich Eisenia foetida

Inadequate management of solid organic waste can lead to the spread of diseases and negatively affects the environment. Fermentation and vermicomposting of organic waste could have dual benefits by generating earthworm biomass for a source of animal feed protein, and, at the same time, turning the organic waste into readily used compost. This study investigated the effect of an organic waste source (as a sole source or blended with others) totaling 24 media for the cultivation of the earthworm Eisenia foetida. Eight media sources were applied, namely cow manure, horse manure, goat manure, broiler chicken manure, market organic waste, household organic waste, rice straw, and beef rumen content. E. foetida was cultivated for 40 days, then the number of cocoons, earthworms, and the total biomass weight were measured at the end of the cultivation. Results demonstrated that the media source affected E. foetida earthworm cultivation. The most effective media were those containing horse manure that led to the production of the highest earthworms and the highest biomass. The produced cocoons and earthworms were poorly correlated with an r-value of 0.26 and p-value of 0.21. Meanwhile, the number and weight of the earthworms correlated well with an r-value of 0.784 and p-value of &lt;0.01. However, the average numbers and weights of the produced earthworms in the media containing horse manure, cow manure, goat manure, and non-blended organic waste were insignificant. Overall results suggest that blended organic wastes can undergo composting to produce nutrient-rich earthworm biomass while turning the solid organic waste into readily used compost.

Conversion of spent coffee grounds into vermicompost

The present study was focused on vermicomposting of spent coffee grounds (SCG) and its mixtures with straw pellets. The process was evaluated in terms of biological and physico-chemical properties. The greatest number and biomass of earthworms was found in the treatment with 25% vol. SCG + 75% vol. straw pellets. In this treatment, the upper youngest layer exhibited 1.6-fold and 4.5-fold greater earthworm number and biomass, respectively, than the bottom oldest layer. Earthworm weight decreased in direct proportion to the layer age. The oldest treatment layer was characterized by lesser contents of fungi and six hydrolytic enzymes, compared to the younger layers. Further, the oldest treatment layer had suitable agrochemical properties. Earthworms were able to substantially reduce the caffeine stimulant content, which is considered the most representative pharmaceutically active compound.

Effects of Gleditsia sinensis pod powder, coconut shell biochar and rice husk biochar as additives on bacterial communities and compost quality during vermicomposting of pig manure and wheat straw

This study investigated the effectiveness of Gleditsia sinensis pod powder (GSPP), coconut shell biochar (CSB), rice husk biochar (RHB) and their mixtures on vermicomposting of pig manure and wheat straw using Eisenia fetida. The results indicated that the addition of GSPP or/and CSB and RHB could greatly enhance the relative abundance of Bacteroidetes, Actinobacteria, and Firmicutes, as well as the activities of celluloses, protease, and alkaline phosphatase. However, the earthworm biomass was increased in the GSPP and/or CSB addition treatments but decreased in RHB addition treatments compared with the control. Compared with the control, addition of 4%GSPP+8%CSB significantly (P < 0.05) accelerated the degradation of organic matter and increased the concentration of nutrients (total N, P, K), NO3--N in final vermicompost. Germination and growth of tomato seedings were also higher (P < 0.05) in vermicompost produced with the addition of 4%GSPP+8%CSB than in control. Consequently, 4%GSPP+8%CSB addition was suggested as an efficient method to improve the vermicomposting of pig manure and wheat straw.

Earthworm Abundance Changes Depending on Soil Management Practices in Slovenian Vineyards

Earthworms are key indicators of soil quality and health in vineyards, but research that considers different soil management systems, especially in Slovenian viticultural areas is scarce. In this investigation, the impact of different soil management practices such as permanent green cover, the use of herbicides in row and inter-row areas, use of straw mulch, and shallow soil tillage compared to meadow control for earthworm abundance, were assessed. The biomass and abundance of earthworms (m2) and distribution in various soil layers were quantified for three years. Monitoring and a survey covering 22 May 2014 to 5 October 2016 in seven different sampling dates, along with a soil profile at the depth from 0 to 60 cm, were carried out. Our results showed that the lowest mean abundance and biomass of earthworms in all sampling periods were registered along the herbicide strip (within the rows). The highest abundance was found in the straw mulch and permanent green cover treatments (higher than in the control). On the plots where the herbicide was applied to the complete inter-row area, the abundance of the earthworm community decreased from the beginning to the end of the monitoring period. In contrast, shallow tillage showed a similar trend of declining earthworm abundance, which could indicate a deterioration of soil biodiversity conditions. We concluded that different soil management practices greatly affect the soil’s environmental conditions (temperature and humidity), especially in the upper soil layer (up to 15 cm deep), which affects the abundance of the earthworm community. Our results demonstrated that these practices need to be adapted to the climate and weather conditions, and also to human impacts.

Earthworm communities are supported by perennial bioenergy cropping systems

During the last decade a variety of perennial bioenergy crops (PECs) have been introduced into European agriculture. This study was designed to investigate the impact of various PECs on earthworm community patterns (species composition, numbers, biomass, α-diversity, life-form categories) at a landscape scale in Western Germany. The PECs investigated were cup plant (CP), tall wheatgrass (TW) and giant knotweed (GK). In total, 4 field replicates of each perennial crop were investigated at 9 study sites with the exception of CP, for which only 3 replicate sites were available. PECs were compared with silage maize as an annual bioenergy crop (AEC) and permanent grasslands (PGL). The earthworm community of the study area consisted of 13 species in total. Mean species number ranged from 2.7 (AEC) < 2.8 (GK) < 3.8 (TW) < 3.9 (PGL) < 4.2 (CP). Overall, PECs took an intermediate position between AEC and PGL concerning earthworm population data including α-diversity and community structure as indicated by Shannon-Weaver index (H’), species number and Evenness (E). There was a clear and close to significant (p < 0.1) increase in the mean total earthworm number in the range AEC (43.3 ind. m−2) – PECs (86.7 ind. m−2) – PGL (114.4 ind. m−2). Fresh earthworm biomass varied from 21.1 g m−2 (AEC) to 35.7 g m−2 (PGL) to 40.1 g m−2 (PECs), however, this difference was only significant for mean biomass of juveniles. Endogeic species were highly dominant in soils cultivated with PECs. Generalized linear mixed models revealed that soil pH, amounts of soil organic carbon and plant available soil water content were partly significant environmental driving variables for the improvement of the earthworm community in soils cultivated with PECs.

Effect of the 32nd-year Soil Tillage and Nitrogen Fertilization on the Population and Biomass of Earthworm under Zea mays L.

The abundance and biomass of earthworms are affected by soil tillage and fertilization. This research aimed to study long-term 32nd-year soil tillage and nitrogen fertilization on the population and biomass of earthworms under Zea mays L. The research was conducted using a randomized block design (RBD) which consisted of two factors. The first factor was the soil tillage that was Intensive Tillage (IT), Minimum Tillage (MT), and No-Tillage (NT). The Second factor was nitrogen fertilization that was N0 = 0 kg N ha-1 and N1= 200 kg N ha-1. Data of earthworm population and biomass were tested using analysis of variance and continued with the least significant difference (LSD) test at the 95% significant level. The population and biomass of earthworms at MT or NT were higher than IT. The population and biomass of earthworms in the plots without fertilization were higher than those at 200 kg N ha-1. There was an interaction between the soil tillage and N fertilization on earthworm biomass observed 60 days after planting at a 0-10 cm depth. There was a positive correlation between soil pH and earthworm population and biomass before the tillage phase.

Distribution of epi-endogeic and endogeic earthworm species (Oligochaeta: Lumbricidae) in the forest belt of the Northwest Caucasus.

The distribution of the often dominant in density and biomass epi-endogeic and endogeic earthworm species in forests of the Northwest Caucasus was estimated based on a large array of field data and GIS modeling of modern potential areas. Quantitative accountings of earthworms were conducted annually from 2014 to 2019 in different types of forests: sticky alder forest, small-leaved forests, broadleaf forests (hornbeam and beech forests), coniferous-deciduous forests, dark coniferous forests, and pine forests (792 geographic locations). It is shown that the native species of the Caucasian fauna dominate in the number and biomass from piedmont to high mountain forests. The most widespread species that is found in all types of forests from low to high mountains and makes the main contribution to the biomass of earthworms is the Crimean-Caucasian subendemic Dendrobaena schmidti. Peregrine species of epi-endogeic and endogeic earthworms inhabit sticky alder forest, small-leaved, broadleaf and pine forests in which they inhabit together with native species, while not dominating either in numbers or in biomass among other species. Dark coniferous forests are inhabited mainly by the native endogeic species D. schmidti and A. jassyensis. Maxent modeling shows that the species of the endogeic earthworm group have wider potential areas than epi-endogeic species. The most significant bioclimatic factors that make the greatest contribution to the distribution: amount of precipitation in the driest month, altitude above the sea level, isothermality.