This document discusses the drilosphere, which is the zone of soil influenced by earthworm activity and casts. It describes the components of the drilosphere, including the earthworm gut microbiome and secretions, casts, middens, and burrows. These structures and secretions influence soil organic matter dynamics, microbial communities, aggregation, porosity, and plant growth. The drilosphere interacts closely with other spheres like the rhizosphere to regulate key soil functions over various spatial and temporal scales. Soil organic matter pools are also impacted, with earthworms and microbes influencing active and protected carbon.

1. Regulation Of Soil Organic MatterRegulation Of Soil Organic Matter
Dynamics And Microbial Activity InDynamics And Microbial Activity In
The Drilosphere And The Role OfThe Drilosphere And The Role Of
Interactions With Other EdaphicInteractions With Other Edaphic
Functional DomainsFunctional Domains
Presented By-
Ishwar Prakash Sharma

2. Functions of Soil MicrobesFunctions of Soil Microbes
 Decomposition & Transformation
 In the Ecosystem Process
 For Biological Interaction
 Improving Soil Quality

3. Soil QualitySoil Quality
Soil Quality Concept
Soil Quality is defined as how well soil does
what we want it to do. Healthy soil gives us
clean air and water, bountiful crops and forests,
productive rangeland, diverse wildlife, and
beautiful landscapes.
It is the capacity of soil to maintain some key
ecological functions, such as decomposition and
formation of soil organic matter. Microbial
processes are important for the improvement of
soil quality.

4. DrilosphereDrilosphere
 The term was coined by Bouche, originally to
describe the zone 2 mm thick around earthworm
burrow walls, while the term ‘vermisphere’ was
used by Hamilton and Dindal for Lumbricus
terrestris .
 Lavelle expended the meaning of ‘drilosphere’ to
include earthworm populations and all the soil
volume, microbial and invertebrate populations
affected by earthworm activities.

5. Drilosphere ComponentsDrilosphere Components
(According to Bouche)(According to Bouche)
Mucus (Microbial Primer)
Earthworm salivary gland produces their body mucus
it is rich of nutrients and polysaccharides.
 Earthworm Excretion
It is byproducts of gut passage and it contains
mainly nitrogenous compound. It is in the form of
cast.

6. Main Components Of DrilosphereMain Components Of Drilosphere
(According to Lavelle)(According to Lavelle)
 The internal micro-environment of the earthworm
gut
 The earthworm surface in contact with soil
 Surface and below-ground casts
 Middens and
 Burrows.

7. The internal micro-environment ofThe internal micro-environment of
the earthworm gutthe earthworm gut
 Microbes - Proteobacteria, Aspergillus flavus, A.
fumigatus, and Streptomyces aureus.
Earthworm enzymes
 The major enzymes found in the gut of different
earthworm species are: chitinase, protease,
phosphatase, cellulase and many other glucosidic
enzymes
 These enzymes allow them to digest bacteria,
protozoa, fungi and partly decomposed plant debris

8.  No enzymes capable of digesting lignin or other
polyphenolic and humified substances have been
found so far
 Peroxidases, which destroy the aromatic links of
lignin, have been observed in earthworm guts (e.g.
Eisenia fetida)
 Few detailed studies on earthworm gut glucosidic
enzyme systems has been performed
 Each species had a distinct enzyme complex and
activity, and its origin could be from the gut wall,
or from the microbiota living in the gut.

9. Mutualistic digestion of soil organic matter in earthworm guts.

10. Myxococccales, Bacilli, Verrucomicrobia and
Planctomycetes, Aspergillus flavus, A.
fumigatus, and Streptomyces aureus. The bacteria
of family ‘Lumbricoplasmataceae’ (obligate
earthworm-associated organisms) and
Gammaproteobacteria (Escherichia coli, Vibrio
cholerae, Pseudomonas aeruginosa, Salmonella spp.
etc.) and although bacteria of the genus
Pseudomonas, Alphaproteobacteria, and
Alcaligenes faecalis.
The earthworm surface in contactThe earthworm surface in contact
with soilwith soil

11. Surface and below-ground casts
Earthworms excrete material known as casts. Surface
casts are usually deposited by earthworms that form
vertical burrows. The casts are very fertile,
containing digested soil and plant material, and
microbial agents that continue to transform nutrients.
They are usually high in phosphorus, nitrogen and
potassium.
Types:- Globular Granular

12. MiddenMidden
 Midden, a pile of cast material mixed with leave
stems and debris about 5 cm in diameter and perhaps
1-2 cm high.

13. BurrowsBurrows
Burrows, produced as the earthworm works its way
through the soil, can be permanent or temporary, are
mostly important in water and gaseous exchange and
movement into the soil, and can serve as
preferential pathways for plant root expansion.

14. Drilosphere & PorosphereDrilosphere & Porosphere
Earthworm derived pores are of two types-
• Macropores (>2mm in diameter)
• Micropores (<2mm in diameter)
The rhizosphere, or the zone <0.5 mm
surrounding plant roots, deeply influenced by
earthworm, both
Drilosphere & Rhizosphere
• Directly
• Indirectly

15. Overlap of the drilosphere with the other edaphic biological regulation
spheres.

16. Schematic representation of the functional relationships between
earthworms and their external environment .

17. The effect of drilosphere structures and processes (internal and external) on
soil organic matter dynamics and microbial activity at different scales of space
and time, from the earthworm gut up to the soil profile and from a few hours
up to decades of time.

18. The effect of earthworms and microbes on active and protected soil C pools. Circle and
box sizes represent the approximate contribution of each pool to the total soil C.
Earthworms are considered separately from the active C pool for graphical purposes and
because they act as a controlling mechanism in the processes of C protection
(stabilization) and priming (disturbance).

19. Soil Organic Matter (SOM)Soil Organic Matter (SOM)
SOM is the organic matter component of
soil. It can be divided into three general
pools:-
 Living biomass of microorganisms
 Fresh and partially decomposed residues
 Humus: the well-decomposed organic
matter and highly stable organic material.

20. Components of SOMComponents of SOM

21. CONCLUSION
The drilosphere can exert and important
regulatory role in soil function including
its –
 physical structure (aggregation, porosity),
 Chemical properties and processes,
 biological interactions and plant
production.
There is considerable overlap between the

22. ReferencesReferences
 Brown GG, Baroisa I, and Lavelle P (2000) Regulation of soil organic
matter dynamics and microbial activity in drilosphere and role of interaction
with other edaphic functional domains. Eur J Soil biol. 36:177-198.
 Drake HL and Horn MA (2007) As the Worm Turns:The Earthworm Gut as
Transient Habitat for Soil Microbial Biomes. Annu Rev Microbiol. 61:169–89.
 Kumar R, Singh BL, Verma D and Shweta (2010) Enzyme Activities and
Microflora of Earthworm Gut and Vermireactors as Indicators of the
Stabilization of Waste Degradation Process. Bioremediation Journal, 14(3):150–
157.

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