Earthworm activities and the soil system (original) (raw)

Earthworms: 'Soil and Ecosystem Engineers' – a Review

World Journal of Agricultural Research, 2014

Earthworms can alter the soil environment by changing soil properties. They have great potentiality to enhance soil physical properties like bulk density, infiltrability, hydraulic conductivity, porosity, aggregate stability. Due to this ability they are only species which plays significant role in pedoturbation. Similarly, their role in nutrient cycling and organic matter breakdown is of unique interest. Earthworm cast fortified with the microbial population. Increasing microbial activity in soil, increases the nutrient mineralization and release. Earthworm activity enhances root distribution so that immobile macro nutrients like phosphorous and other micronutrients, which are absorbed by plant through root interception, are easily available to the plants. Hence, earthworms play important role in bioturbation, they are considered as 'soil engineer.' However, their activity differs with the agroecosystems. Their population density is more in reduced tillage system than conventional tillage system, aerobic condition than anaerobic conditions, grasslands than forest. Low population of earthworm was found in dry land agroecosystems. But earthworm presence in extreme environment is not studied well yet. So, this paper was reviewed to explore the role of earthworm as soil and ecosystem engineer. This was already established fact but main aim of this paper is to collect the related information and conclude the future research prospects to strengthen the earthworm role as soil and ecosystem engineer.

Earthworms: Ecosystem and soil Engineers - a review

Earthworms can alter the soil environment by changing soil properties. They have great potentiality to enhance soil physical properties like bulk density, infiltrability, hydraulic conductivity, porosity, aggregate stability. Due to this ability they are only species which plays significant role in pedoturbation. Similarly, their role in nutrient cycling and organic matter breakdown is of unique interest. Earthworm cast fortified with the microbial population. Increasing microbial activity in soil, increases the nutrient mineralization and release. Earthworm activity enhances root distribution so that immobile macro nutrients like phosphorous and other micronutrients, which are absorbed by plant through root interception, are easily available to the plants. Hence, earthworms play important role in bioturbation, they are considered as 'soil engineer.' However, their activity differs with the agroecosystems. Their population density is more in reduced tillage system than conventional tillage system, aerobic condition than anaerobic conditions, grasslands than forest. Low population of earthworm was found in dry land agroecosystems. But earthworm presence in extreme environment is not studied well yet. So, this paper was reviewed to explore the role of earthworm as soil and ecosystem engineer. This was already established fact but main aim of this paper is to collect the related information and conclude the future research prospects to strengthen the earthworm role as soil and ecosystem engineer.

EARTHWORM AS SOIL ECOSYSTEM ENGINEERS: A REVIEW

Earthworm and microorganisms are interdependent on each other. The interactions between them help to regulate the biogeochemical cycle of terrestrial life. A large diversity of fungi, bacteria, yeast, actinomycetes and protozoa are found to be present in the gut and cast of earthworms. Their number and species depend on their feed substrates obtained in soil. It has been studied that the microbial proliferation is more in the casts, due to the environment prevailing-rich nutrient supply and large surface area available for growth and reproduction of the microbes that lead to the enhanced microbial activity and humic acid contents in casts. Diversity of microorganisms is also found in vermicompost and vermiwash. This in turn depended on the raw material used for compost. A significant increase was noted in flora after composting. Within an ecological group, habitat was found to be a more important determinant of the gut wall associated community composition than the host species.

Impacts of earthworms on soil components and dynamics. A review

Earthworm populations are important decomposers contributing to aggregate formation and nutrient cycling processes involving nitrogen cycles, phosphorus and carbon. They are known to influence soil fertility by participating to important processes in soil such as soil structure regulation and organic matter dynamics. Earthworms also modify the microbial communities through digestion, stimulation and dispersion in casts. Consequently, changes in the activities of earthworm communities, as a result of soil management practices, can also be used as indicators of soil fertility and quality. It is therefore important to understand how earthworm communities affect soil dynamics. This review adresses the current state of knowledge on earthworm's impacts on soil structure and soil organic matter (carbon, nitrogen, and phosphorus) dynamics, with special emphasis on the effects of land management practices on earthworm communities.

A review of earthworm impact on soil function and ecosystem services

European Journal of Soil Science, 2013

Biodiversity is responsible for the provision of many ecosystem services; human well-being is based on these services, and consequently on biodiversity. In soil, earthworms represent the largest component of the animal biomass and are commonly termed ‘ecosystem engineers’. This review considers the contribution of earthworms to ecosystem services through pedogenesis, development of soil structure, water regulation, nutrient cycling, primary production, climate regulation, pollution remediation and cultural services. Although there has been much research into the role of earthworms in soil ecology, this review demonstrates substantial gaps in our knowledge related in particular to difficulties in identifying the effects of species, land use and climate. The review aims to assist people involved in all aspects of land management, including conservation, agriculture, mining or other industries, to obtain a broad knowledge of earthworms and ecosystem services.

Role of Earthworms in Soil Fertility and Factors Affecting Their Population Dynamics: A Review

2015

Earthworms mix soil layers and incorporate organic matter into the soil. This mixing allows the dispersion of the organic matter through the soil and makes the nutrients held in it available to plants and improves the fertility of the soil. Earthworms when present improve the soil physical, chemical and biological properties and acts as soil conditioner. They do so by fragmentation, aeration, breakdown of organic matter in soil and release plant available nutrients and also due to secretion of plant growth hormones, their role in nitrogen fixation, carbon dynamics, and phosphorous dynamics. But their population in soil is threatened by a number of soil and environmental factors. Agricultural practices like heavy tillage operation and application of chemical fertilizers also contribute in the reduction of earthworms in soil. Change in land use due to increase in human population brings change in the system and make it unsuitable for the growth and development of earthworms. This revi...

Effects of Earthworms on Soil Structure and Physical Properties

2016

1Laboratoire Biologie et Organisation des Sols Tropicaux, IRo, Fort-de-France, Martinique; 2Laboratoire d'Étude du Comportement des Sols Cultivés, IRD, Montpellier, France; 3/CRAF, La Molina, Peru/Laboratoire d'Ecologie des Sols Tropicaux, IRo, Bondy, France; 5Laboratoire de Pédobiologie, IRo, Dakar, 5enegal; 6Department of Terrestrial Ecology and Nature Conservation, Agricultural University, Wageningen, the Netherlands; 7ICRAF/INIA, Estaci6n Experimental 'San Ram6n', Yurimaguas, Peru