Soil organic matter distribution and microaggregate characteristics as affected by agricultural management and earthworm activity

Stable microaggregates can physically protect occluded soil organic matter (SOM) against decomposition. We studied the effects of agricultural management on the amount and characteristics of microaggregates and on SOM distribution in a marine loam soil in the Netherlands. Three long‐term farming systems were compared: a permanent pasture, a conventional‐arable system and an organic‐arable system. Whole soil samples were separated into microaggregates (53–250 µm), 20–53 µm and < 20 µm organo‐mineral fractions, sand and particulate organic matter, after complete disruption of macroaggregates. Equal amounts of microaggregates were isolated, irrespective of management. However, microaggregates from the pasture contained a larger fraction of total soil organic C and were more stable than microaggregates from the two arable fields, suggesting greater SOM stabilization in microaggregates under pasture. Moreover, differences in the relative contribution of coarse silt (> 20 µm) versus fine mineral particles in the microaggregates of the different management systems demonstrate that different types of microaggregates were isolated. These results, in combination with micromorphological study of thin sections, indicate that the great earthworm activity under permanent pasture is an important factor explaining the presence of very stable microaggregates that are relatively enriched in organic C and fine mineral particles. Despite a distinctly greater total SOM content and earthworm activity in the organic‐ versus the conventional‐arable system, differences in microaggregate characteristics between both arable systems were small. The formation of stable and strongly organic C‐enriched microaggregates seems much less effective under arable conditions than under pasture. This might be related to differences in earthworm species' composition, SOM characteristics and/or mechanical disturbance between pasture and arable land.     

Earthworm burrowing activity of two non-Lumbricidae earthworm species incubated in soils with contrasting organic carbon content (Vertisol vs. Ultisol)

The aim of this study was to investigate the burrowing activity of two earthworm species: the endogeic Drawida sinica and one undescribed Amynthas species incubated in Vertisol and Ultisol presenting different soil organic C content. Because of their contrasting feeding behaviours, we hypothesised that soil type would have a bigger influence on the burrowing activity of the endogeic than the anecic species. Repacked soil columns inoculated with earthworms for 30 days were scanned using X-ray tomography and the compiled images used to characterise the burrow systems. After scanning, the saturated hydraulic conductivity (K _sat) was also measured. The Amynthas species burrows were less numerous (30 vs. 180), more vertically oriented (57 vs. 37°), more connected from the surface to the bottom of the columns (73 vs. 5 cm³) and had a higher global connectivity index (83 vs. 28%) than those of D. sinica. The K _sat was threefold faster in columns incubated with Amynthas and was linked to the volume of percolating burrows (R ² = 0.81). The soil type did not influence Amynthas burrow characteristics. In contrast, there were 30% more D. sinica burrows in the Vertisol than in the Ultisol while other burrow characteristics were not affected. This result suggests that these burrows were more refilled with casts leading to shorter and discontinuous burrows. The K _sat was negatively related to the number of burrows (R ² = 0.44) but was not statistically different between the Vertisol and the Ultisol, suggesting a constant impact of this species on the K _sat. We found that a decrease in the amount of soil organic C by 50% had only a small influence on earthworm burrowing activity and no effect on the K _sat.     

Discrete functional pools of soil organic matter in a UK grassland soil are differentially affected by temperature and priming

We show that both temperature and priming act differently on distinct C pools in a temperate grassland soil. We used SOM which was ¹⁴C-labelled in four different ways: by labelling soil with ¹⁴C-glucose, by adding leaf litter from plants pre-labelled with ¹⁴CO₂, and by labelling in situ with ¹⁴CO₂ applied to the ryegrass canopy either 6 or 18 months earlier. Samples of each type of ¹⁴C labelled soil were incubated at either 4, 10, 15, or 20 °C and the exponential loss of ¹⁴CO₂ used to characterise treatment effects. ¹⁴C allocation to microbial fractions was greater, and so overall mineralization by microbes was greater, as temperature rose, but turnover of the microbial labile pool was temperature-insensitive, and the turnover of microbial structural material was reduced as temperature rose. The ability of the microbial population to degrade just one fraction of plant litter was increased greatly by temperature. A pool of SOM with a half-life of about 70 d was degraded faster at higher temperatures. Less tractable but abundant pools of SOM were not accessed more readily at higher temperatures by the microbial population. Priming with glucose or amino-acids only speeded the mineralization of recent SOM (probably from the living microbial biomass), and was not altered by temperature. These results have implications for the impacts of climate change on soil C cycling.     

Changes in forest soil organic matter quality affected by windstorm and wildfire

Purpose

Windthrows and fires are major natural disturbances in forest ecosystems, which can affect organic matter in the surface and the mineral layer of forest soil. The main aim of this study was to evaluate the changes occurring in the structure and properties of humic acid (HA) in the lands where windthrows and wildfires occurred.

Materials and methods

In November 2004, the forest in the area of 12,000 ha in the Tatra National Park, Slovakia, was seriously damaged by northern wind gusts exceeding 200 km/h. In July 2005, a wildfire broke out in a 220 ha of wind-damaged area. The HAs have been isolated from four research plots: (a) the area where the fallen trees were removed (EXT); (b) an area after windstorm covered by wood from struck trees (NEX), left for spontaneous succession; (c) an area after extracted timber, damaged by the surface wildfire (FIR); and (d) a reference intact spruce forest area (REF). Changes in the chemical structure of the HAs isolated from the research plots were determined on the basis of elemental analysis and UV-Vis, EPR, IR, and ¹³C NMR spectroscopy.

Results and discussion

All used analytical methods showed a decrease in the humification degree of the humic acids extracted from the soils where the spruce forest has been affected by a wildfire and a windthrow. In the case of the control sample HA (REF), the calculated atomic H/C and O/C ratios and the degree of aromaticity (α) calculated from the ¹³C NMR spectra were higher, indicating higher aromaticity of HA from the REF area. The more complex and developed structure of REF HA was confirmed by the higher value of E^1%₆ and the lower E4/E6 ratio obtained using UV-Vis spectroscopy. Also, the higher g-parameters determined from the EPR spectra of the stable radicals present in HA confirmed the lower aromaticity on the plots that have been subjected to the calamities. The ¹³C NMR spectra and the elemental analysis show that the structure of the HA extracted from the NEX plot is the closest to the REF.

Conclusions

The results of the systematic research showed significant changes in the structure of HA taken from spruce forest soils that were subjected to windstorms and fires. An enrichment of the HAs in aliphatic carbon and so a lower humification degree of the organic matter in the areas calamity-affected were observed. The results clearly indicate that the HAs extracted from the disturbed plots of the spruce forest are not as stable as those extracted taken from the control plot.

     

On the determination of total heavy metal content in saline soils and soils rich in organic matter

Abstract

Methods of soil decomposition for determination of heavy metal total content were considered. Two saline soils (chloride and sulphate solonchak solonetz) and one rich in organic matter were uzed for investigation. It has been established that decomposition by using HF‐HCl with a preliminary ignition at 500°C is a very suitable method. The type of the studied soils and the results obtained allow for this method to be recommended for decomposition of various soils.

On the basis of experiments with modelled soils it has been proved that possibilities for heavy metal losses on ignition are created when NaCl content and the percentage of weakly bound heavy metals (water‐soluble, exchangeable, etc.) are high. Under the conditions of the experiment (acid soils ‐ pH 4.3 and 5.0) losses of Zn and Pb but not of Cu have been incurred. Although these cases are not typical, this requires the applicability of the method for such particular occasions to be checked.     

Variability of the quality and quantity of organic matter in soil affected by multiple wildfires

Purpose

Fire in mountainous areas can lead to increased variability of their soil organic matter (SOM) due to spatial inhomogeneity and pre-fire fuel distribution. Here, we elucidated if this was the case in our study area and how this affected the reliability of solid-state ¹³C NMR spectroscopy applied for the study of the medium-term impact of fire on SOM

Materials and methods

The study occurred in the Sierra de Aznalcóllar, Southern Spain, which experienced their last intense fire 7 years before sampling. In a first approach (method 1), the corners and the center of a randomly chosen square with a side length of 15 m were sampled and analyzed separately. For comparison, composite samples (method 2) were obtained from three soils. We characterized material from unburnt, burnt, and double burnt regions. Data describing the physical and chemical properties of the soils together with the NMR spectroscopic characterization were analyzed using ANOVA.

Results and discussion

Both sampling methods yielded comparable results with comparable standard errors. No major differences between the fire-affected and unburnt soils were observed with respect to physical and chemical properties and C and N contents, but solid-state ¹³C NMR spectroscopy indicated a small but significant elevation of aromaticity in the soils with fire history.

Conclusions

The analysis showed that sampling with reduced replicates (method 1) can still lead to representative NMR data. The more complex sampling of comparing three composite samples (method 2) did not decrease the standard error. Our results also indicate that in the study area typical properties of the soil and its SOM induced by former burnings will not persist beyond a few decades.

     

Mulching effect of plant residues of chemically contrasting compositions on soil organic matter content and cation exchange capacity

Abstract

Effects of five types of plant residues [Acioa, presently Dactyladenia barteri, Gliricidia sepium, and Leucaena lecocephala prunings, maize (Zea mays) stover and rice (Oryza sativa) straw] applied as mulch on soil organic matter (SOM) content and effective cation exchange capacity (ECEC) were studied on an Alfisol in the humid tropics. Plant residue mulch resulted in a decline in SOM and ECEC during two years of cropping following six years of grass fallow. Rice straw mulch resulted in less and maize stover mulch in a greater decrease of SOM and ECEC than the other mulches. Decrease in SOM and ECEC is attributed to the mulching effect on the soil micro‐climate which enhanced the decomposition of SOM accumulated during the grass fallow prior to the initiation of the experiment. In order to maintain SOM for a tropical soil, plant residues with high lignin, polyphenols, and silica will have to be among residue species when applied in continuous cropping systems.     

Compaction and rotovation effects on soil pore characteristics of a loamy sand soil with contrasting organic matter content

The high input of mechanical energy in common agricultural practice can negatively affect soil structure. The impact of compaction (P) and rotovation (R) on soil pore characteristics was compared with those in soil from untreated reference (U) plots of a loamy sand soil receiving for 14 yr, either only mineral fertilizer (MF) or, in addition, animal manure (OF). Undisturbed soil cores were taken from two separate fields in consecutive years at an identical stage in the crop rotation. We measured soil organic carbon (OC), soil microbial biomass carbon (BC), and hot‐water extractable carbon (C_hot). Water retention, air permeability and gas diffusivity were determined at ?100 hPa in both years and for a range of water potentials in one of the years. The continued addition of animal manure had increased OC, BC, and C_hot compared with the soil receiving only mineral fertilizer. Soil under treatment OF had larger porosity than that from treatment MF. Treatment P eliminated this difference and significantly reduced the volume of macropores. This interaction between soil organic matter content and mechanical impact was also reflected in the gas diffusion data. Specific air permeability was mainly influenced by mechanical treatment. Modelling the diffusion data normalized to the inter‐aggregate pore space showed no significant treatment effects on pore‐connectivity, although there was a tendency of more water blockage in soil under treatment MF. More studies are needed to confirm this interpretation. Our studies indicate that organic manure increases soil porosity, but compaction reduces the related gas exchange effects to the level of compacted soils receiving mineral fertilizer.     

高温快速发酵对鸡粪重金属形态分布及有机质含量影响

以鸡粪、玉米秸秆为主要原料,通过添加酵素进行好氧堆肥发酵试验,研究了不同温度和时间下堆肥 pH值、EC值、重金属含量与形态、腐殖质含量变化以及红外光谱特征。结果表明,与堆肥前相比,pH值随温度升高和时间的延长而增大,最大可增加 0.53个单位,而 EC值随堆肥时间延长表现为先增加后降低的趋势,在 85℃处理下最低。由于浓缩效应,重金属含量均不同程度增加,Cu、Zn、Cr、Cd和 As含量较堆肥前相比最大增幅分别达到35.6%、11.5%、35.0%、35.3%和23.8%。然而,重金属可交换态分配率则有所降低,残渣态比例相应增加,与堆肥前相比,鸡粪有机肥中Cu、Zn、Cr、Cd和 As钝化率分别为24.8%、26.0%、27.6%、26.9%和13.9%。高温处理下,胡敏酸和富里酸含量较低,胡敏酸 /富里酸(HA/FA)比值随着堆肥时间和温度增加而增大,且随着堆肥进程脂肪族、芳香族、羧酸类分子以及多糖类物质均有所减少。结果显示高温下(85℃)不仅加快堆肥发酵进程,而且可以有效钝化重金属,可达到无害化效果。     

铵、钾同时存在时, 土壤对铵的优先吸附

The water stability of aggregates in various size classes separated from 18 samples of red soils under different managements, and the mechanisms responsible for the formation of water-stable soil aggregates were studied. The results showed that the water stability of soil aggregates declined with increasing size, especially for the low organic matter soils. Organic matter plays a key role in the formation of water-stable soil aggregates. The larger the soil aggregate size, the greater the impact of organic matter on the water stability of soil aggregates. Removal of organic matter markedly disintegrated the large water-stable aggregates (> 2.0 mm) and increased the small ones (< 0.25-0.5mm) to some extent, whereas removal of free iron(aluminium) oxides considerably destroyed aggregates of all sizes, especially the < 0.25-0.5 mm classes. The contents of organic matter in water-stable aggregates increased with aggregate sizes. It is concluded from this study that small water-stable aggregates (< 0.25-0.5 mm) were chiefly cemented by Fe and Al oxides whilst the large ones (> 2.0 mm) were mainly glued up by organic matter. Both free oxides and organic matter contribute to the formation and water stability of aggregates in red soils.     

Soil aggregate stability and organic matter as affected by land-use change in central Iran

This study aimed to evaluate the soil aggregate stability and selected soil quality indicators in various land uses in a semiarid region in central Iran. Random soil sampling was used to collect soil samples from surface (0–5 cm) and subsurface (5–25 cm) soil layers in rangelands of different condition classes, dry farmland and abandoned land. The aggregate size distribution indices including mean weight diameter (MWD), geometric mean diameter (GMD) and median diameter (D₅₀) of water-stable aggregates in the collected soil samples were measured. Our findings showed that percent of macroaggregates (>0.25 mm) of the surface and subsurface layers in rangelands of different condition classes were significantly higher than dry farmlands and abandoned lands (P < 0.05). Results showed that the trend of changes in soil organic matter was similar to soil aggregate stability in different land uses in both soil layers as follows: rangeland with good condition > rangeland with poor condition > abandoned land > dry farmlands. The structural stability indices (i.e. MWD, GMD and D₅₀) of rangelands with good condition were significantly greater than other land uses (P < 0.05). This highlights the importance of maintaining native rangeland to prevent organic matter loss, structure deterioration and soil erosion.     

Clonal diversity and morphometry in the parthenogenetic earthworm Eiseniella tetraedra (Sav.) as affected by habitat characteristics including radioactive pollution

Eiseniella tetraedra (Sav.) is a cosmopolitan earthworm reproducing by obligate parthenogenesis. Here, we examined whether habitat characteristics affected the clone pool diversities and morphometric variability of the stenotopic riparian species E. tetraedra along a west–east transect from the Scandinavian mountains to lowland habitats of the Swedish east coast through Finland and to Russia (the Komi Republic) near the Ural Mountains. The transect comprised a geographical distance that cuts through the maritime to continental climatological zones within the boreal forest belt. It terminated in the Komi Republic, thus adding habitat (soil) characteristics to the factor of radioactive pollution. We found that mountain brooks in Sweden hosted the lowest numbers of clones, but in the lowland samples the clone pool diversities decreased in general from Sweden through Finland and Russia, i.e. from west to east. Nevertheless, high levels of clonal variability were observed within the countries, so that even monomorphic pools were found. However, no clones were shared between the countries. The fresh body weights and posterior body lengths of adult earthworms decreased from west to east. The numbers of posterior segments did not, however, differ between the countries, due to decreased segment size. The location of the clitellum, tubercula pubertatis and male pores showed no clear-cut morphometric clines along the W–E gradient, but the tubercula pubertatis and male pores were more clearly demarcated in adults of the Russian material than in those from the West. Eiseniella adults from the Swedish mountains carried spermatophores considerably more often than those from the other localities. E. tetraedra from localities with radioactive pollution in Russia (the Komi Republic) showed no clear-cut clone pool diversities in comparison to the clone pools of the other sites within the area. Monomorphic clone pools were recorded in localities with low as well as high levels of long-term ionizing radiation and exposure to heavy metals. We found no morphological malformations, such as dislocations of characters, in comparison to individuals from sites with lower levels of environmental radiation.     

Modelling the transformations and sequestration of soil organic matter in two contrasting ecosystems of the Andes

The mechanisms linking soil respiration to climate and soil physical properties are important for modelling transformation and sequestration of C and N in the soil. We investigated them by incubating ¹⁴C and ¹⁵N labelled straw in soils of the dry puna (Bolivian altiplano, semi‐arid shrubland at 3789 m above sea level) and the humid paramo (Venezuelan tropical alpine vegetation at 3400 m). These two ecosystems of the high Andes are comparable in terms of altitude, mean temperature and land use, but are very different regarding organic matter content, rainfall patterns and soil physical properties. Total ¹⁴C and ¹⁵N, microbial‐biomass ¹⁴C and ¹⁵N, soil moisture and meteorological data were recorded over 2 years. Daily soil moisture was predicted from a water balance model. The data from the paramo site were used to calibrate MOMOS‐6, a model of organic matter decomposition based on microbial activity and requiring only kinetic constant parameters to describe: (i) inputs to microbial biomass from plant debris and microbial metabolites, and (ii) losses from the biomass by mortality and respiration (respiration coefficient and microbial metabolic quotient qCO₂). The simulated qCO₂–¹⁴C agrees well with qCO₂–¹⁴C and qCO₂ measured at the calibration site and with published data. To apply MOMOS‐6 to the puna site, only the respiration coefficient of the biomass was re‐estimated. The dynamics of ¹⁴C and ¹⁵N were very different in the two systems. In the puna, the transformation processes stop during the long dry periods, though total annual mineralization is greater than in the paramo. The change in the value of the respiration coefficient enables us to predict that the amount of C and N sequestered in the stable humus is greater in the paramo than in the puna. The data in this paper can be used to estimate values of the respiration coefficient so that MOMOS‐6 can be applied to other systems.     

Effect of earthworm cast formation on the stabilization of organic matter in fine soil fractions

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

26年连作影响下土壤酶活性和有机质组成

The study was to determine the long-term effects of subtropical monoculture and rotational cropping systems and fertilization on soil enzyme activities and soil C, N, and P levels. Cropping systems included continuous sorghum(Sorghum bicolor L.), cotton(Gossypium hirsutum L.), corn(Zea mays L.), and cotton/sorghum rotations after 26 years of treatment imposition. Soil under continuous sorghum and continuous corn had 15% and 11%, respectively, greater C concentrations than soil under continuous cotton.Organic C was 10% higher at 0–7.5 cm than at 7.5–15 cm. Total N followed similar trends with soil depth as organic C. Continuous sorghum had 19% higher total N than other crop species and rotations. With fertilization, continuous cotton had the highest total P at 0–7.5 cm and sorghum had the highest at 7.5–15 cm. Soil total P was 14% higher at 0–7.5 than at 7.5–15 cm, and fertilization increased 15% total P compared to unfertilized soil. Arylsulfatase, alkaline phosphatase, and β-d-glucosidase activity were the highest for sorghum and the lowest for cotton. Rotation increased enzyme activities compared to continuous cotton but not for continuous sorghum. Of all crop species and rotations, continuous cotton generally showed the lowest levels of organic matter and enzyme activities after 26 years. Fertilization significantly increased the yields for all cropping systems, but rotation had no significant effect on either sorghum or cotton lint yield compared to each crop grown in monoculture. Long-term cropping did not increase soil organic matter levels beyond short-term gains, indicating the difficulty in promoting C sequestration in subtropical soils.     

Potassium retention and leaching in an organic crop rotation on loamy sand as affected by contrasting potassium budgets

Abstract. In organic farming, potassium (K) deficiency may become a significant problem due to nutrient import restrictions. Knowledge about potential K leaching in systems with different K budgets is therefore important for effective agricultural management. We investigated the effect of four organic farming systems (two livestock densities in combination with two types of organic manure) on crop yields, K leaching and K balances in a six course crop rotation from 1993/94 to 1997/98. Average K concentrations in soil water extracted by means of ceramic suction cups at 1 m depth were 0.6 mg K l⁻¹ corresponding to a K leaching loss of 1.5 kg ha⁻¹ yr⁻¹ which was less than expected from values reported in the literature. Variation in K budgets from −12 to +30 kg ha⁻¹ yr⁻¹ did not affect K leaching. In an additional experiment with application of 988 kg K ha⁻¹ as KCl, K leaching accounted for only 0.2% of the applied K although 40% of the accompanying Cl was leached. The main part of the applied K was retained in the topsoil. It was concluded that K leaching was a result of the fertilizer history rather than of the current K budget.     

Heavy metal accumulation by two earthworm species and its relationship to total and DTPA-extractable metals in soils

The concentrations of Zn, Cd, Pb and Cu in earthworm tissues were compared with the total and DTPA-extractable contents of these heavy metals in contaminated soils. Samples were taken from a pasture polluted by waste from a metallurgic industry over 70 y ago. Three individuals of Aporrectodea caliginosa and Lumbricus rubellus and soil samples were collected at six points along a gradient of increasing pollution. Total metal contents of earthworms, soil, and metals extracted by DTPA from the soil were measured. Total heavy metal contents of the soils ranged from 165.7 to 1231.7 mg Zn kg⁻¹, 2.7 to 5.2 mg Cd kg⁻¹, 45.8 to 465.5 mg Pb kg⁻¹ and 30.0 to 107.5 mg Cu kg⁻¹. Their correlations with metals extracted by DTPA were highly significant. Contents of the metals in earthworm tissues were higher in A. caliginosa than in L. rubellus, with values ranging from 556 to 3381 mg Zn kg⁻¹, 11.6 to 102.9 mg Cd kg⁻¹, 1.9 to 182.8 mg Pb kg⁻¹ and 17.9 to 35.9 mg Cu kg⁻¹ in A. caliginosa, and from 667.9 to 2645 mg Zn kg⁻¹, 7.7 to 26.3 mg Cd kg⁻¹, 0.5 to 37.9 mg Pb kg⁻¹ and 16.0 to 37.6 mg Cu kg⁻¹ in L. rubellus, respectively. Correlations between body loads in earthworms with either total or DTPA-extractable contents of soil metals were significant, except for Cd in L. rubellus and Cu in A. caliginosa. Considering its simple analytical procedure, DTPA-extractable fraction may be preferable to total metal content as a predictor of bio-concentrations of heavy metals in earthworms. Biota-to-Soil Accumulation Factor (BSAF) of these four metals are Cd>Zn>Cu>Pb, with range of mean values between: Cd (6.18-17.02), Zn (1.95-7.91), Cu (0.27-0.89) and Pb (0.08-0.38) in A. caliginosa, and Cd (3.64-6.34), Zn (1.5-6.35), Cu (0.29-0.87) and Pb (0.04-0.13) in L. rubellus. The BSAF of Ca, Fe and Mn are Ca>Mn>Fe, with mean values of: Ca (0.46-1.31), Mn (0.041-0.111), Fe (0.017-0.07) in A. caliginosa and Ca (0.98-2.13), Mn (0.14-0.23), Fe (0.019-0.048) in L. rubellus, respectively. Results of principal component analysis showed that the two earthworm species differ in the pattern of metal bioaccumulation which is related to their ecological roles in contaminated soils.     

Regulation of soil organic matter dynamics and microbial activityin the drilosphere and the role of interactionswith other edaphic functional domains

The moment the soil enters into contact with an earthworm, both superficially and internally, physicochemical and biological changes take place. The drilosphere represents the whole soil volume under earthworm influence. Thus it includes the body surfaces, the gut and all the internal features of the worm that are in contact with the ingested soil, as well as the external structures (casts, burrows, middens) created by earthworm activities. The extent of the drilosphere and its particular characteristics depend on the species and ecological categories of the earthworm community present as well as the spatial and temporal scale of interest. Spatially, the drilosphere can interact with other soil functional domains and lead to significant changes in the litter system or detritusphere (generally decreasing litter stocks) and the rhizosphere (affecting both root biomass and density), the two main sources of organic matter (OM) additions to the soil, as well as in the aggregatusphere and the porosphere. Drilosphere effects on microbial activity and OM decomposition can be completely different (and opposite) depending on the spatio-temporal scale of observation. At the level of the gut, microbial activity is dramatically stimulated in a matter of a few hours via a mutualistic digestion system. In this process, water and soluble-C in the form of intestinal mucus (the Kiss) produced by the earthworm (Prince Charming) awakens the dormant microflora (Sleeping Beauties), thereby increasing decomposition of the stable forms of soil OM ingested. During gut passage populations of other organisms (e.g. protozoa, nematodes, fungi) may decline with digestion, although these organisms probably form a minor component of the earthworm’s energy needs. In the casts and on the burrow walls, the abundant nutrient resources for soil microflora continue the priming effect of the gut, increasing over a short time period mineralization rates and plant nutrient bio-availability. However as castings, particularly of the ‘compacting group’, and burrow walls begin to dry and stabilize with age (days to weeks), OM decomposition, nutrient mineralization and microbial activity decrease, often reaching levels lower than uningested soil due to ‘protection’. Finally at the scale of years to decades and soil profile, it appears that the drilosphere can exert an important regulation on OM incorporation and turnover rates, and soil C stocks.