Earthworm Abundance Research Articles

Land management modulates the environmental controls on global earthworm communities

AbstractAimSoils and their biological communities face increasing pressure from multiple global drivers, including land management and climate change. In soils, earthworms play key roles in ecosystem functioning, but the environmental controls on their global communities are not fully understood. Here, an earthworm dataset was compiled to investigate the effects of environmental variables and land management on global earthworm communities.Location40° S–65° N.Time period1962 to 2016.Major taxa studiedEarthworms.MethodsA dataset of 899 earthworm community observations, together with environmental variables, was compiled across 169 globally distributed sites. Sites included natural forest and grassland or managed arable, pasture and plantation ecosystems. Total, anecic, endogeic and epigeic abundances and total species richness were compared in natural and managed ecosystems to quantify the effects of land management across climates. A hierarchical model was used to test the importance of environmental controls in predicting the relationship between total earthworm species richness and abundance at a global scale.ResultsLand management prompted little change in total earthworm abundance at the global scale, but reduced species richness and shifted community composition. Endogeic earthworms were more abundant in managed ecosystems, while anecic and epigeic earthworms showed variable responses across ecosystem types. Global relationships between total earthworm species richness and abundance were explained by climate, soil pH and land management.Main conclusionsLand management modulates the effects of environmental controls on global earthworm communities, through direct disturbance and indirect changes in edaphic conditions.

Earthworm community and soil microstructure changes with long-term organic fertilization

ABSTRACTThe aim of this study was to evaluate the effects of sludge compost (SC) in two rates and pig slurry (PS) on soil quality, in the framework of a field experiment (19-year-old) in a Mediterranean rainfed system. The treatments were compared with mineral fertilization (MF) plus a control treatment (no N fertilization). Soil microstructure and types of voids, earthworm community and its bioturbation were studied using micromorphological methods. Two earthworm species, Koinodrilus roseus and Nicodrilus trapezoides were identified; the latter was not present in the SC treatments. Earthworm abundance and biomass were not affected by fertilization. Pig slurry increased bioturbation associated with earthworm activity, improved soil microstructure (crumb type) and increased the biopore presence (compound packing voids). The control and MF plots showed a platy to massive microstructure with an absence of faunal chambers. In SC plots, non-mixed soil-organic materials were observed and soil vughs were not visible. Composition differences between SC and PS and the total amount of OM applied may have had an impact on the activity and species of earthworms; such changes can be an early indicator of further potential impacts on soil quality, however further contaminant studies are needed to validate this initial assessment.Abbreviations: CO: control; DM: dry matter; MF: mineral fertilizer; OM: organic matter; PS: pig slurry; SC: sewage sludge compost.

Woodland restoration on agricultural land: long‐term impacts on soil quality

Woodland restoration is underway globally to counter the negative soil quality and ecological impacts of agricultural expansion and woodland fragmentation, and restore or enhance biodiversity, ecosystem functions and services. However, we lack information about the long‐term effects of woodland restoration on agricultural soils, particularly at temporal scales meaningful to woodland and soil development. This study utilized soil and earthworm sampling across a chronosequence of sites transitioning from “agricultural land” to “secondary woodland” (50–110 years) and “ancient woodland” (>400 years), with the goal of quantifying the effects of woodland restoration on agricultural land, on key soil quality parameters (soil bulk density, pH, carbon and nitrogen stocks, and earthworm abundance, biomass, species richness and diversity). Broad‐leaved woodland restoration led to significantly greater soil organic carbon (SOC) stocks compared to arable land, and young (50–60 years) secondary woodland increased earthworm species and functional diversity compared to both arable and pasture agricultural land. SOC stocks in secondary broad‐leaved woodlands (50–110 years) were comparable to those found in long‐term ancient woodlands (>400 years). Our findings show that broad‐leaved woodland restoration of agricultural land can lead to meaningful soil ecological improvement and gains in SOC within 50–110 years, and provide intel on how restoration activities may be best targeted to maximize soil quality and functions.

Developing a systematic sampling method for earthworms in and around deadwood

BackgroundThe ecological importance of deadwood is widely acknowledged, however popular forestry practices may reduce deadwood from a site, and most European forests now fall below recommended targets, putting deadwood-associated species at risk. There is increasing evidence that earthworm species which live in alternative habitats such as deadwood can be missed by traditional sampling methods, which can lead to false classifications regarding species distributions and conservation status and value. Resolving the current lack of a systematic and quantitative methodology for surveying earthworms in microhabitats such as deadwood may therefore lead to valuable insights into earthworm species ecologies in forest ecosystems. The main aim of this research was to develop and trial a systematic method for surveying deadwood-associated earthworms, with potential future application to other invertebrates. Sampling of earthworms within soil, deadwood and soil beneath deadwood was carried out across a chronosequence of unmanaged oak forest stands. The results were then used to investigate the influence of soil and deadwood environmental factors and woodland age on the earthworm populations of oak-dominated broadleaf woodlands.ResultsResults from our surveys successfully show that in oak woodland habitats with deadwood, omitting deadwood microhabitats from earthworm sampling can lead to underestimates of total earthworm species richness, abundance and biomass. We also found a significantly greater proportion of juveniles within the earthworm communities of broadleaf deadwood, where temperature and moisture conditions were more favourable than surrounding open soil habitats.ConclusionsThe systematic method presented should be considered as additional and complementary to traditional sampling protocols, to provide a realistic estimate of earthworm populations in woodland systems. Adopting this quantitative approach to surveying the biodiversity value of deadwood may enable forest management practices to more effectively balance wood production against ecological and conservation values. Opportunities for further development of the sampling methodology are proposed.

The effects of various tillage treatments on soil physical properties, earthworm abundance and crop yield in Hungary

Historically, tillage has been essential for seedbed preparation and weed control, but it has also accelerated soil degradation through erosion and loss of soil organic matter (SOM). Our objective was to quantify the changes in soil physical properties and earthworm abundance under six tillage treatments on an Endocalcic Chernozem (Loamic) soil (2016 and 2017). The long-term tillage experiment was set up in 2002 with the following tillage treatments: disking 12 to 14 cm deep (D); shallow tine cultivation (18 to 20 cm) (SC); no-tillage (NT); deep tine cultivation (22 to 25 cm) (DC); loosening to a depth of 40 to 45 cm (L); moldboard ploughing to a depth of 28 to 30 cm, followed by leveling (P). Soil samples were collected in the autumn of 2015 from four depth increments (0–10, 10–20, 20–30, 30–40 cm). Soil moisture content (SMC), soil penetration resistance (SPR), soil texture, pH(H2O), soil organic carbon (SOC), and earthworm abundance were measured. SMC and SPR were taken at 30-day intervals unless the weather prevented sampling. Earthworms were sampled in situ seven times per year by hand-sorting 25 × 25 x 30 cm soil blocks. No-tillage had a positive effect on crop yield and earthworm abundance. Compared to conventional tillage (P), SMC and SPR were improved by conservation tillage (DC, SC, D or NT). When measured during the summer months, SPR reached 6 MPa for all tillage treatments due to low SMC. Overall, NT had the highest earthworm abundance while conventional tillage (P) had the lowest. Maize (Zea mays L.) yield was highest with SC (9.32 Mg ha−1), lowest with D (7.92 Mg ha−1). For winter oat (Avena fatua L.), L resulted in the highest yield (5.87 Mg ha−1) but required more time and energy. As weather patterns become more erratic, tillage has the potential to make crop production even riskier. Therefore, to improve both physical and biological soil properties, efforts should be made to decrease tillage intensity each year.

Fertilización con purín porcino: impacto sobre las lombrices de tierra en agricultura de secano

Earthworms play an important role in the maintenance of soil ecosystem services. Their presence and activity are influenced by agricultural practices as fertilization. The objective of this research was to identify earthworm species and to quantify their abundance and biomass in a field experiment where different fertilization strategies were applied for a period of 12 years. The experiment was carried out under a semiarid Mediterranean climate, in a fallow year of a rainfed cereal system. Fertilization strategies were based on pig slurries from fattening pigs (PE) and from sows (PM) at different fresh doses distributed in six treatments: three treatments only included PE (one rate was 30 t ha−1 yr−1 applied at pre-sowing, and the other two treatments received 40 and 60 t ha−1 yr−1 applied at cereal tillering), two treatments only included PM (60 and 90 t ha−1 yr−1 applied at cereal tillering) and the last, it combined PE and PM (30 t ha−1 yr−1 of PE at pre-sowing plus 90 t ha−1 yr−1 of PM at cereal tillering). Fertilization included a mineral fertilization treatment (0−FM) acting as a control. There were no variations in the abundance and biomass of earthworms registered according to the type of fertilization. Two earthworm species were identified. The endogeic species Koinodrilus roseus was the most abundant (80%−100%). The anecic species Nicodrilus trapezoides was not detected in plots receiving the two highest doses of PE at cereal tillering. The absence of N. trapezoides can be considered as a bioindicator of PE over-fertilization.

Tillage and residue management drive rapid changes in soil macrofauna communities and soil properties in a semiarid cropping system of Eastern Colorado

Tillage and stover harvest are common management practices in maize-based cropping systems around the globe. However, frequent soil disturbance and biomass export are likely to have negative long-term impacts on soil biological activity and a range of associated soil properties, and thus, there is great concern surrounding the sustainability of these practices. To address this issue, we examined soil macrofauna communities and a suite of soil chemical and physical properties in a recently established experiment (2.5 yrs. old) in Akron, Colorado. No-tillage and residue retention practices were included in a full factorial randomized block design with the following treatments: no-till + residue retention (NT/R); no-till + residue harvest (NT/RH); conventional tillage + residue retention (CT/R); and conventional tillage + residue harvest (CT/RH). In year three of the experiment, soil health parameters were assessed including: soil macrofauna diversity and abundance, aggregate stability, potential infiltration, and chemical fertility measures. The combined practice of residue retention with no-tillage (NT/R) resulted in greater macrofauna abundance, including a five-fold increase in earthworm abundance and biomass. Greater earthworm populations were associated with an increase in aggregate stability and a trend towards greater water infiltration under NT/R. While univariate tests did not reveal significant treatment differences in arthropod taxa, multivariate analyses indicated clear treatment effects on macrofauna communities, with tillage generally separating communities more than residue management. Soil chemical parameters indicated relatively less dramatic differences between treatments, but with some notable impacts of both residue retention and tillage on soil C and N dynamics. Findings from our study, among the first to examine whole soil macrofauna communities in the semi-arid Great Plains, suggest that no-till and residue retention practices offer promise for improving soil biological activity and soil structural properties of soil, especially when these two practices are employed in combination.

Earthworms contribute to ecosystem process in no-till systems with high crop rotation intensity in Argentina

In the Pampas region of Argentina agriculture is dominated by intensive no-till (NT) soybean cropping which produce negative consequences on soil quality. A group of farmers started to use the Good Agricultural Practices (GAP) which include a higher crop rotation, use of winter cover crops and nutrient restoration. In this NT system earthworms have a significant role in soil functioning, particularly in organic matter cycling and soil structure formation. The aim of this paper was to examine the contribution of earthworm activity to the process of C incorporation and soil structure maintenance in soils with different NT variants of: NT with GAP for 30 years (NT + r30); NT with some of the GAP for 12 years (NT-r12) and NT with soybean monoculture (NTm). Also a natural grassland (NA) was sampled as a reference. Earthworm aggregates were obtained by gently separating them from surrounding soil. Fine (HOC) and coarse (POC) organic matter fractions, water-stable aggregates (WSA) and mean weight diameter (MWD) were calculated for earthworm aggregates and bulk soil. In all sites only one species (Aporrectodea caliginosa) was found, with higher density in the NA, followed by NT + r30, that had about 9 times more earthworms than NTm. The number of earthworm aggregates was higher in the NT + r30 followed by the NA, both showing differences with the other NT systems. The earthworm aggregates in NA and NT + r30 had significantly more POC than the surrounding soil (230% increase in NA and 100% NT + r30). Earthworm casts had higher values of MWD and WSA than physical soil aggregates in both NA and NT + r30 management treatments. Our results show the existence of a positive feedback loop we called earthworm-driven virtuous cycle. The increase in earthworm abundance promotes higher production of earthworm aggregates which are richer in organic matter and more water stable than the surrounding soil. This has favourable results in terms of soil quality but also increase crop yields (57% in maize and 18% in soybean), by means of biologically mediated soil processes, which is a highly desirable way to sustainability of agricultural production. Farmers, politicians and the whole society should pay more attention to soil as a key component supporting agricultural production by means of internal biological soil functioning.

Pioneer plant Phalaris arundinacea and earthworms promote initial soil structure formation despite strong alluvial dynamics in a semi-controlled field experiment

Soil structure formation is among the most important processes in river floodplains which are strongly influenced by alluvial dynamics. In the context of river restoration projects, a better understanding of soil structure formation in habitats adjacent to the river can help to prevent damages caused by riverbank erosion. Ecosystem engineers such as pioneer herbaceous plants and earthworms likely contribute to soil structure formation even despite less favourable environmental conditions. This study aims to assess the capacity of the herbaceous perennial and native species Phalaris arundinacea and earthworm communities to promote a stable soil structure in alluvial sediments, in particular fresh alluvial deposits, in the short term. Delimited plots were set-up in a restored floodplain adjacent to the Thur River in NE Switzerland and exposed to natural alluvial dynamics for 19 months. Four treatments were replicated in a randomised complete block design: (i) plots with Phalaris arundinacea as only vegetation, (ii) plots with all vegetation constantly removed, (iii) and (iv) the earthworm community reduced by mustard treatment, otherwise as (i) and (ii), respectively. Soil structure formation was analysed at the end of the experiment using different indicators: aggregate stability, field-saturated hydraulic conductivity and the porosity calculated from X-ray CT reconstructions of freeze cores. Phalaris arundinacea was capable of improving the porosity and aggregate stability of both alluvial sediments present at the beginning of the experiment but also of sediments freshly deposited during the observation period. The latter indicates a structuring effect within only one vegetation period. Earthworm abundance was as a whole very low, most likely due to the large proportion of sand. There was a small earthworm effect on soil structure formation, and only in combination with Phalaris.arundinacea. Our findings highlight the ability of Phalaris arundinacea in efficiently structuring sandy alluvial sediments in the short term even under strong alluvial dynamics. Phalaris arundinacea can therefore play a key role in the early stage of river restoration projects. Thus, facilitating the colonisation by such native pioneer herbaceous plants is a suitable step to improve the success of river restoration projects.

Intensive Cultivation of Kiwifruit Alters the Detrital Foodweb and Accelerates Soil C and N Losses.

The detrital food web plays an important role in the functioning of agro-ecosystems due to their positive effect on organic matter transformations and nutrient supply to the growing crops, however, the activities of the organisms involved are strongly influenced by agricultural practices. In NW Spain, commercial Hayward kiwifruit (Actinidia chinensis var. deliciosa) is intensively produced using conventional techniques (CONV), however, more sustainable methods, such as integrated (INT) and organic (ORG), have been increasingly adopted to decrease the negative impacts on the environment. We investigated the effects of these agricultural managements on earthworm abundance and functional diversity as well as microbial biomass and enzyme activity and evaluated the potential implications for nutrient retention and runoff in kiwifruit orchards. Our results showed that the CONV soils significantly contained fewer earthworms (ca. 80% less individuals than the INT and ORG systems), with their communities being mainly dominated by small epigeics, but a higher microbial biomass (0.53 ± 0.06 mg C g-1 dw soil compared to <0.25 mg C g-1 dw soil in INT and ORG), and 20% more activity of the enzymes involved in C (β-glucosidase) and N mineralization (urease). Consequently, more C and N was lost from these soils (on average, >37% more CO2, and five times more DIN) than from the less intensively managed soils. In contrast, the INT and ORG systems sustained a more complex and functionally diverse soil food web that lead to higher soil C and N retention. Therefore, agriculture management (i.e., intensive vs. less intensive) and its effects on the structure of the below-ground communities (i.e., microorganisms plus surface detritivores vs. deep burrowers plus geophagous forms) determine the nutrient sink/source function of these agro-ecosystems. These findings highlight the importance of including the contribution of soil biota to soil processes when optimizing fertilization loads and mitigating environmental impacts of agricultural practices.

Invasive earthworm and soil litter response to the experimental removal of white-tailed deer and an invasive shrub.

Recent studies have shown that complex species interactions can regulate above- and belowground processes in terrestrial systems. Ungulate herbivory and invasive species are known to have strong effects on plant communities in some systems, but their impacts on soil biota and belowground processes are lesser known. Growing evidence suggests white-tailed deer (Odocoileus virginianus) and invasive plants facilitate increased abundance of exotic earthworms in temperate forests of the eastern United States. We conducted an experimental study that manipulated deer access and the presence of an invasive understory shrub in an eastern deciduous forest of southwestern Ohio, USA, from 2013 to 2017. Earthworm density and biomass, and standing litter biomass were measured in five paired deer access and exclosure plots, each with a split-plot removal of Amur honeysuckle (Lonicera maackii). Earthworm density declined in response to the experimental exclusion of deer, with earthworm density decreasing over time in the deer exclosure plots relative to deer access plots. Deer exclusion produced greater variation in earthworm species composition relative to access plots. Multivariate analyses indicated that larger earthworms in the genus Lumbricus were associated with deer exclosure plots, while smaller endogeic species were ubiquitous in both treatments. Standing litter biomass decreased over time in the deer-access plots. In contrast, honeysuckle removal had little effect on earthworm density and standing litter biomass. There was an interaction between deer and honeysuckle treatments on earthworm biomass, with honeysuckle removal reducing earthworm biomass when deer were excluded. Our results demonstrate strong effects of herbivores on invasive earthworms and ecosystem processes, but indicate a weaker influence of invasive shrubs. Further, our findings suggest that the effects of deer overabundance in forest ecosystems are potentially reversible with long-term intervention.

Earthworm activity and availability for meadow birds is restricted in intensively managed grasslands

Abstract Earthworms are an important prey for the endangered meadow birds of northwest Europe. Although intensive grassland management with high manure inputs generally promotes earthworm abundance, it may reduce the effective food availability for meadow birds through desiccation of the topsoil, which causes earthworms to remain deeper in the soil. We studied the response of Red Worm Lumbricus rubellus, a detritivore, and Grey Worm Aporrectodea caliginosa, a geophage, to soil moisture profiles in the field and under experimental conditions. Surfacing earthworms were counted weekly in eight intensively managed grasslands (treated with high inputs of slurry by slit injection) with variable groundwater tables in the Netherlands. At each count, soil penetration resistance, soil moisture tension and groundwater level were measured, while air temperature and humidity were obtained from a nearby weather station. The response to variation in the vertical distribution of soil moisture was also experimentally studied in the two earthworm species. In the field, earthworms’ surfacing activity at night was negatively associated with soil moisture tension and positively by relative air humidity. Surprisingly, there was no effect of groundwater level; an important management variable in meadow bird conservation. Under experimental conditions, both L. rubellus and A. caliginosa moved to deeper soil layers (&gt;20 cm) in drier soil moisture treatments, avoiding the upper layer when moisture levels dropped below 30%. Synthesis and applications. We propose that in intensively managed grasslands with slurry application, topsoil desiccation reduces earthworm availability for meadow birds. This can be counteracted by keeping soil moisture tensions of the top soil above −15 kPa. We suggest that the late raising of groundwater tables in spring and the disturbance of the soil by slit injection of slurry increase topsoil desiccation. This decreases earthworm availability when it matters most for breeding meadow birds. Meadow bird conservation will benefit from revised manure application strategies that promote earthworm activity near or at the soil surface.

Earthworms affect decomposition of soil-borne plant pathogen Sclerotinia sclerotiorum in a cover crop field experiment

Earthworms provide important ecosystem services in agricultural systems. However, little is known with regards to which extent earthworms feed on soil-borne plant fungal pathogens, thereby potentially reducing pathogen infection of crops. Using a food choice arena in the laboratory, we examined (i) whether the hardened resting structures (i.e., sclerotia) of white mould (Sclerotinia sclerotiorum (Lib.) de Bary) are consumed by the earthworm Lumbricus terrestris L. (Lumbricidae) and (ii) to what extent this consumption is affected by a possible hydration of sclerotia. We found that earthworms fed on sclerotia, preferably when sclerotia were hydrated. After 13 weeks of sclerotia hydration, on average, 61.1 ± 26.0% were consumed. In field plots, we further tested the interaction between earthworms, cover crops (mustard (Sinapis alba L.), oilseed radish (Raphanus sativus subsp. oleiferus M.), oat (Avena sativa L.), grass pea (Lathyrus sativus L.)) and sclerotia. After eight months, the number of remained sclerotia was lower when earthworms had access (51 ± 19%) than when earthworm had restricted access (79 ± 11%; Sidak; P = 0.01). Oilseed radish increased earthworm abundance, however cover crops did not directly reduce sclerotia. Our findings indicate that sclerotia can be reduced by supporting cover crops that favour earthworms rather than having bare fallow.

Changes in the abundance and diversity of earthworms in hill soils under different long-term fertiliser and sheep stocking regimes

ABSTRACT This study examined the earthworm community in permanent pastures at three self-contained farmlets that make up the long-term P fertiliser and sheep grazing study located at Ballantrae Hill Country Research Station. Thirty five years after the study was established, earthworm abundance was lower at the farmlet receiving no fertiliser since 1979 (LFNF, 219 m−2), compared to that receiving 125 kg SSP/ha/year (LFLF, 384 m−2) or 375 kg SSP/ha/year (HFHF, 428 m−2). Earthworm species diversity increased from two in 1979, to nine in 2014, as a result of both accidental and deliberate anthropogenic earthworm introductions. Across all farmlets earthworm abundance was closely associated with pasture production, as well as several pasture attributes and soil variables, particularly those influenced by slope. Maximising the contribution of soil fauna to soil function in hill country requires recognising the influence of slope on earthworm habitats and associated resource availability.

Predictors and consequences of earthworm invasion in a coastal archipelago

Non-native earthworms can drive ecosystem change, simplify native plant communities, and promote invasion by non-native plants, but we know little about their pathways into island archipelagos, which currently support about 40% of the worlds threatened species. We studied links among non-native earthworms, human settlement, deer, and plant communities on 26 islands in the San Juan and Southern Gulf Island archipelagos of the Georgia Basin Ecoregion of western North America. We evaluated the (1) invasion pathways and occurrence of non-native earthworms on islands, (2) influence of non-native earthworms on herbaceous and woody plant cover, and (3) potential for synergistic interactions among deer, earthworms and non-native plants. Human settlement was a pre-condition to detecting non-native earthworms on islands. Non-native earthworm abundance was related positively to the cover of non-native herbaceous and woody plants, effects which may be exacerbated by high deer density. Our findings suggest that the absence of non-native earthworms on many small islands makes their protection crucial to the conservation of intact examples of native ecosystems, including critically endangered Garry oak and maritime meadows in Canada.

Exotic earthworms maintain soil biodiversity by altering bottom-up effects of plants on the composition of soil microbial groups and nematode communities.

Bottom-up effects of plants on soil communities can be modified by the activity of exotic earthworms, by altering resource availability for soil food webs through feeding, burrowing, and casting activities. The present study explored effects of plants (planting of shrubs) on soil micro-food webs (composition of soil microbial and nematode communities), and whether these effects were altered by the activity of exotic earthworms (exotic earthworms addition). Planted shrubs resulted in a non-significant increase of bacterial biomass and significantly increased the abundance of different nematode trophic groups and total nematode biomass, indicating that planted shrubs had significant bottom-up effects on soil bacteria and nematodes. Planted shrubs decreased nematode diversity, evenness, and richness, but increased nematode dominance in the plots where the abundance of exotic earthworms was not amended. By contrast, these effects of shrub presence on soil biodiversity were not found in the plots that received exotic earthworms. In addition, planted shrubs increased the total energy flux to the nematode community. By contrast, the elevated activity of exotic earthworms mitigated the increase in total energy flux to nematodes in the presence of shrubs, and increased the ratio of fungal to bacterial PLFAs. Both of these changes indicate reduced energy flux in the plots with added exotic earthworms. Nematode diversity decreased, while nematode dominance increased with increasing total energy flux to nematodes, probably because few species benefited from high energy flux. Our study indicates that exotic earthworms can maintain soil biodiversity by reducing the energy flux through soil food webs.

Improvement of several indicators of physical and biological properties of soil after adding crops biomass residues and yield of upland rice

Returning and addition of organic material to soil is a key to protecting the soil, plants, and the environment. A study aimed to elucidate the effect of residual biomass application on some indicators of soil physical properties, abundance of earthworms and soil microbial activities was conducted in Kebun Percobaan (KP) Natar, BPTP Lampung from February to July 2017. The treatments were three types of crops biomass residues, i.e., maize stover, rice straw, and soybean stover (fresh or compost). The dosage rates were 0, 2.5, 5.0, 7.5, and 10 t/ha. The treatments were arranged in a randomized block design with three replicates. Upland rice (Inpago 9 variety) was planted after two weeks application of biomass residues treatments. The results showed that application of crops biomass residues improved bulkdensity and significantly increased soil water content at the high dose of biomass residues (7.5 or 10 t/ha). The amount and weight of earthworms with added of compost biomass was significantly correlated with soil water content (r values 0.491 and 0.376, respectively). The dose of biomass residues had a significant effect on soil respiration that the highest soil respiration was obtained in maize compost biomass treatment (at 12 weeks observation) was 31.7 and rice straw compost (at 8 weeks observation) which was 30.19 mg/hour/m2 C-CO2.

Combining agro-ecological functions in grass-clover mixtures

Grass-clover mixtures show many benefits for sustainable agriculture. In the Netherlands, organic farmers often work together in a so-called partner farm concept, with the aim to close nutrient cycles on a regional level. In this system, arable farms grow one-year grass-clover leys, as fodder for a livestock farm, in exchange for, e.g., manure. This practice could also be used in the transition of conventional farms towards a more circular regenerative and nature inclusive agriculture. In the current experiment we assessed the effect of a range of grass (Lolium perenne: Lp, Lolium multiflorum: Lm) and clover (Trifolium pratense: Tp and Trifolium repens: Tr) monocultures and mixtures on both below- and aboveground parameters in light of benefits for livestock and arable farms, and biodiversity. The grass monocultures showed good weed suppression, high root density, and especially Lp had a positive effect on soil structure. Clover, on the other hand, showed high herbage dry matter yield (particularly Tp) and Nitrogen (N) yield, and Tr showed high digestibility. Moreover, clover had a positive effect on the soil mineral N, and earthworm abundance tended to be higher in the clover monocultures. When (some of) the four species were combined in grass-clover mixtures, they combined the positive effects of the species and often even outperformed the (best) monocultures. We concluded that grass-clover mixtures increased agro-ecological functions.

How dairy farmers manage the interactions between organic fertilizers and earthworm ecotypes and their predators

Most Dutch dairy farmland today is fertilized with slurry, a mixture of cattle dung and urine. As a food source for earthworms, this type of organic fertilizer is of lower quality than the traditionally used farmyard manure consisting of dung with some urine and mixed with bedding material such as straw. Earthworms living in dairy farmland belong to two distinct ecotypes, the detritivores and the geophages. Detritivores rely on farmyard manure as a food source more than geophages and therefore the type of organic fertilizer is expected to determine their relative abundances. In turn, this would affect higher trophic levels, as detritivores, when they come to the surface to collect food, are particularly important as prey for birds and mammals. Here we tested the hypothesis that dairy farmland fertilized with slurry will contain fewer detritivorous earthworms (thereby becoming less attractive for earthworm predators) by quantifying the abundance of the two earthworm ecotypes in 45 grasslands fertilized with either slurry, farmyard manure, or both. To determine the availability of detritivores for earthworm predators, we quantified earthworm surface availability by counting surfacing earthworms in the field and compared these numbers with densities belowground. To study the direct effects of different organic fertilizer types on earthworms, we measured their growth rates under controlled constant conditions using either slurry or farmyard manure, with hay as a control. We found that detritivores occurred in the highest densities in grasslands only fertilized with farmyard manure and that they also grew better on farmyard manure than on slurry. These differences were not found in geophages. Detritivores made up 25% of the total earthworm abundance in the soil, but contributed 83% to the surfacing earthworms at night; detritivore earthworms will thus be the main prey for visually hunting earthworm predators. The few dairy farmers using farmyard manure to fertilize their grasslands today will thus encourage the presence and availability of an earthworm ecotype which benefits higher trophic levels such as the endangered meadow birds.

Spatial variation of earthworm communities and soil organic carbon in temperate agroforestry

The aim of this study was to assess how soil organic C (SOC) stocks and earthworm communities were modified in agroforestry systems compared to treeless control plots and within the agroforestry plots (tree rows vs alleys). We used a network of 13 silvoarable agroforestry sites in France along a north/south gradient. Total earthworm abundance and biomass were significantly higher in the tree rows than those in the control plots, but were not modified in the alleys compared to those in the control plots. Earthworm species richness, Shannon index, and species evenness were significantly higher in the tree rows than those in the alleys. Total abundance of epigeic, epi-anecic, strict anecic, and endogeic was higher in the tree rows. Surprisingly, earthworm individual weight was significantly lower in the tree rows than that in the alleys and in the control plots. SOC stocks were significantly higher in the tree rows compared to that in the control plots across all sites. Despite higher SOC stocks in the tree rows, the amount of available C per earthworm individual was lower compared to those in the control. The absence of disturbance (no tillage, no fertilizers, no pesticides) in the tree rows rather than increased SOC stocks therefore seems to be the main factor explaining the increased total abundance, biomass, and diversity of earthworms. The observed differences in earthworm communities between tree rows and alleys may lead to modified and spatially structured SOC dynamics within agroforestry plots.