Biological Sciences
Nematodes in Soil
Nematodes in soil are microscopic roundworms that play important roles in nutrient cycling, decomposition, and soil health. They can be both beneficial and harmful to plants, as some nematodes are parasitic and can damage crops, while others contribute to soil fertility by breaking down organic matter and releasing nutrients. Understanding the diversity and ecological functions of nematodes in soil is crucial for sustainable agriculture and ecosystem management.
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12 Key excerpts on "Nematodes in Soil"
eBook - PDF- Sarma, Brinchi Kuamr(Authors)
- 2018(Publication Date)
- Biotech(Publisher)
The nematodes are basically aquatic animals but they have adopted terrestrial habits (Tunlid and Ahren, 2011). Cobb (1914) remarked that .... if all matter in universe except nematodes were swept away, the world will still be recognizable dimly by its mountains, hills, valleys, lakes and oceans represented by a film of nematodes. At present, the number of known species is about 15,000 but the estimate of existing species is around 5,00,000 or more. It is only in the last few decades ecologist have undertaken detailed studies of belowground soil processes, and this has led to a better understanding of the nature of the soil environment and the complex biological communities that live in soil (Stirling, 2011, Tunlid and Ahren, 2011). Earlier it was assumed that bacteria and fungi are the most numerically abundant member of the soil biota, but culture-independent molecular tools are now indicating that they are far more numerous and diverse than previously thought (Tunlid and Ahren, 2011). Knowledge of the feeding habits of the microfauna ( e.g. protozoa), mesofauna ( e.g. rotifers, nematodes, tardigrades, collembolans, mites and enchytraeids) and macrofauna (e.g. earthworms, termites and millipedes) is also improving, and this is giving us a better insight into the numerous biotic interactions that occur within the soil environment, and how these interactions influence ecosystem processes (Stirling, 2011, Tunlid and Ahren, 2011). Within soil ecosystems, thousand of the nematodes of different kinds-the free living (microbivorous), the predators, and a few hundreds of them plant parasites were living inside the soil (Walia and Bajaj, 2003; Upadhyay and Dwivedi, 2008). For the vast majority of plant-parasitic nematodes, the soil system and its various components constitute their environments.
- Kaushal, K K(Authors)
- 2021(Publication Date)
- Biotech(Publisher)
Nematodes are second only to insects in the number of species in the animal kingdom. One cubic foot of soil may contain millions of individual nematodes belonging to several different taxonomic groups. Amongst the soil inhabitants, they constitute one of the most important groups of organisms which quite often play a vital role in the deterioration of the health of the standing crops. With intensification in agriculture and also with continued and uninter-rupted new introductions in countries, it is obvious that there is likelihood of hitherto unknown problems which may become serious in the near future. The golden nematode problem in Long Islands, U.S.A. and in the southern part of India is one of the most outstanding examples of such type. Considerable information has been generated on the losses caused by the nematodes to staple and other crops in many countries where well established infra structure and man power is available in the subject. At the same time this is also a fact that there is still no reliable information on the exact losses caused by the nematodes to various crops. Most of the reports are approximations based on indirect evidences, interpreted on the basis of pot trials and chemical trials under field conditions. The validity of the results on yield increases, as a result of chemical applications, is open to question since the total effect on biological flora of the soil is not fully understood and This ebook is exclusively for this university only. Cannot be resold/distributed. therefore, it might not be justifiable to interpret results of field trials with nematode damage alone. The quantitative aspect of the nematode damage to the crops is not only affected by the size of the nematode population but also on other variables such as the species of the host plant, temperature and other environmental conditions, the flora and fauna of the soil, which singly or jointly may contribute to the overall expression of disease syndrome.
eBook - PDF- Eric C. Brevik, Lynn C. Burgess, Eric C. Brevik, Lynn C. Burgess(Authors)
- 2012(Publication Date)
- CRC Press(Publisher)
Higher-level predators Nematodes Arthropods Small vertebrates Control the populations of other soil organisms. Source: Modified from Tugel, A., Lewandowski, A., and Happe-von Arb, D. (eds), Soil Biology Primer , Soil and Water Conservation Society, Ankeny, IA, 2000. 20 Soils and Human Health access to sunlight for photosynthesis. Soil algae secrete polysaccharides that have a favorable effect on soil aggregation and are also important in desert environments where they form microbiotic crusts on the soil surface with cyanobacteria, fungi, and other microorganisms. Bacteria are the most diverse group of soil organisms; they occur in all soils, under all conditions, and in all cli-mates. Bacteria participate in virtually all soil organic transactions, including those that promote soil aggregation, making their presence very important to a healthy soil ecosystem. Nematodes are unsegmented roundworms that live in soil water. Most nematodes are either predators of other microorganisms or plant parasites. The plant parasite nematodes can cause serious problems in crop production, but managing agricultural soils to promote conditions that favor predator nematodes can help keep plant parasites in check. Protozoa are mobile, single-celled creatures that include amoebas, ciliates, and flagellates. They release plant-available nitrogen into the soil as they feed and help regulate bacteria populations in the soil through predation. FIGURE 1.14 A termite mound in Africa with a person standing beside it for scale. All the material in the mound has been dug out of the termite tunnels and moved to the soil surface, a process that results in signifi-cant mixing of soil materials and cycling of nutrients. (Courtesy of Jeffrey Homburg.) FIGURE 1.15 The fungi growing on the end of this log are slowly breaking the log down. Eventually, some of the organic materials from the log will be incorporated into the soil the log is laying on. (Photo by Eric Brevik.)
eBook - PDFFauna in Soil Ecosystems
Recycling Processes, Nutrient Fluxes, and Agricultural Production
- Gero Benckiser(Author)
- 1997(Publication Date)
- CRC Press(Publisher)
120 Zunke and Perry VII. FREE LIVING SOIL NEMATODES AND AGRICULTURAL PRODUCTION In comparison to the extensive literature on plant parasitic nematodes, little is known about the contribution of microbivorous, fungivorous, and omnivorous nematodes (Fig. 2) to agricultural production and general ecology. Among the groups of soil fauna, nematodes are ideally suited to use in an ecological soil classification system (Bongers, 1990a) and as an indication of soil quality (Bongers, 1990b). Bongers (1990b) based the ecological classification of nema todes on trophic biology and life strategies: colonizers versus persisters. The development of the Maturity Index (Bongers, 1990b) from this classification has provided a robust, standard biological gauge for different types of environmental disturbance, including pollution effects. Changes in the occurrence of groups of nematodes can be useful as indicators of the effects of heavy metals, acidifica tion, and deposition of nitrogenous compounds, for example. In this approach, nematodes are being used essentially as indicator organisms without any need to assess whether the nematodes are merely responding to change or are actually involved in causing change. There is an increasing interest in the role of nematodes in changing the soil environment through nutrient cycling, and it is now clear that, to assess this role effectively, nematodes need to be assigned more exactly to a feeding habit. Yeates et al. (1993a) list eight different feeding types: (1) plant feeder, (2) hyphal feeder, (3) bacterial feeder, (4) substrate ingester, (5) predator of animals, (6) unicellular eucaryote feeder, (7) dispersal or infective stage of parasites, and (8) omnivore. They consider that accurate group ing of feeding types will aid future understanding of the role of Nematodes in Soil and the influences of environmental factors on populations.
eBook - PDFHandbook of Soil Sciences
Properties and Processes, Second Edition
- Pan Ming Huang, Yuncong Li, Malcolm E. Sumner, Pan Ming Huang, Yuncong Li, Malcolm E. Sumner(Authors)
- 2011(Publication Date)
- CRC Press(Publisher)
Nematodes are particularly useful as bioindicators of organic enrichment and condition of soil food webs (Ferris et al., 2001; Ferris and Bongers, 2006). They have potential as bioindi-cators of pollution from heavy metals (Ekschmitt and Korthals, 2006), and possibly as bioindicators of historical changes and alterations in land use (Todd et al., 2006). As global climate changes, geographic distributions of plant-parasitic nematodes could slowly expand into cooler areas when temperatures increase. Yeates and Boag (2003) speculate that plant-parasitic nematodes and their hosts would likely migrate together. Increasing soil temperature affected the nematode community, resulting in shifts to higher percentages of fungivo-rous and plant-parasitic genera (Ruess et al., 1999). Because the nematode life cycle is temperature-dependent, life cycles would become more rapid, possibly resulting in an extra generation per year in some cases. If agriculture expands into regions that now have short growing seasons, it is likely that the plant-parasitic nematode problems typical of those crops will follow. References Anderson, R.C. 1992. Nematode parasites of vertebrates. CABI, Wallingford, U.K. Andrassy, I. 1976. Evolution as a basis for the systematization of nematodes. Pitman Publishing, San Francisco, CA. Andrassy, I. 1983. A taxonomic review of the suborder Rhabditina (Nematoda: Secernentia). ORSTOM, Paris, France. Ayoub, S.M. 1980. Plant nematology, an agricultural training aid. Nema Aid Publications, Sacramento, CA. Barker, K.R., and C.L. Campbell. 1981. Sampling nematode pop-ulations, p. 451–474. In B.M. Zuckerman and R.A. Rohde (eds.) Plant parasitic nematodes. Vol. 3. Academic Press, New York. Barker, K.R., and C.J. Nusbaum. 1971. Diagnostic and advi-sory programs, p. 303–323. In B.M. Zuckerman, W.F. Mai, and R.A. Rohde (eds.) Plant parasitic nematodes. Vol. I. Academic Press, New York. Barker, K.R., G.A. Pederson, and G.L. Windham. 1998. Plant and nematode interactions.
eBook - PDF- Pierre Davet(Author)
- 2004(Publication Date)
- CRC Press(Publisher)
The simplest and easiest method exploits the ability of these animals to move in water (Fig. 2.10). Other techniques consist of washing the soil on net sieves with progressively smaller meshes in the presence of also Rhabditida stylet Living Components of the Soil 55 Fig. 2.10 Procedure for harvesting soil nematodes. The soil sample is suspended in water and poured into a funnel containing a metallic grill supporting a filter paper at the bottom. A piece of flexible tube, closed with a clip, is attached to the stem of the funnel (a). The nematodes swim and traverse the filter paper. After a few hours, most of them collect at the bottom of the tube (b). They can then be collected in a few ml of the suspension by loosening the clip (c). countercurrents, which prevent sedimentation of the animals with mineral particles. Eventually the resultant suspension is centrifuged. For purposes of counting, 1 ml of a suspension is placed in a haemocytometer cell and observed under the microscope. A large number of samples must necessarily be studied to obtain a correct estimation because the distribution of nematodes in the soil is highly heterogeneous. Most soil nematodes can be maintained artificially in the laboratory on agar media or on plant fragments. Because of the diversity of and number of individuals, nematodes are the most important constituents of the soil animal biomass. Under temperate conditions, their average biomass is in the range of 150 kg ha' 1 . Their number can surpass 200 billion ha 1 , representing a biomass of 200 to 400 kg. Earthworms are annelids, constituting a biomass considerably greater than nematodes. They are agronomically very important and have a role in pedogenesis. However, they are not discussed here because they belong neither to microfauna nor to mesofauna given their large size. Unlike nematodes, the specific diversity of earthworms is very limited, especially in northern regions.
eBook - ePubBiological Control of Plant-parasitic Nematodes
Soil Ecosystem Management in Sustainable Agriculture
- Graham R. Stirling(Author)
- 2014(Publication Date)
- CAB International(Publisher)
Over the last three decades, there has been a major increase in research in soil microbial ecology, and the scientific literature is replete with books, reviews and papers on soil biodiversity, decomposition processes, the soil food web, rhizosphere effects, microorganism–invertebrate interactions and many other related topics. We now know much more about the soil biological community than we did 30 years ago, but this knowledge has not been translated into improvements in the way soil organisms are managed on-farm. For example, research has shown that nematode pests can be suppressed by naturally occurring parasites and predators, and ecologists often indicate that biological suppressiveness is an important ecosystem service, but most farmers have no knowledge of these issues. They assume that crop losses from nematodes are inevitable, and are usually not aware that nematodes have natural enemies that could possibly provide an alternative to nematicides and resistant cultivars.In my opinion, the above situation is the result of the detachment that exists between agricultural scientists, soil ecologists and the farming community. The lack of interaction between the former groups is particularly concerning, and is manifested in some of the issues outlined as follows.• Many agricultural scientists do not view agriculture from an ecological perspective. They focus on maximizing the provisioning services provided by cropping and livestock enterprises, and give little thought to the many other services that an agroecosystem should provide. Their understanding of the energy flows and nutrient cycling processes that occur within agroecosystems is generally relatively simplistic, and their knowledge of soil biological processes is limited. This lack of detailed ecological knowledge, particularly as it relates to soil biology, means that agricultural scientists are unlikely to read the ecological literature, and rarely talk to soil ecologists. Much the same criticism could be applied to discipline-based specialists who work with soil. They tend to work with a limited range of organisms, and their ecological knowledge is often limited to understanding how abiotic factors such as temperature or moisture influence particular soilborne pests or pathogens.
eBook - PDF- Gusau, W L(Authors)
- 2018(Publication Date)
- Agri Horti Press(Publisher)
Cannot be resold/distributed. Soil Machinery and Biological Methods 227 produce hormones that stimulate plant growth. Other strains of Azospirillum fix atmospheric nitrogen and may or may not make it available to the grass. Soil Organisms Dependent on each Other The soil food web is a way of illustrating the way in which soil organisms relate to each other based on what they eat. The soil food web begins with organic matter, such as crop residues, pasture or any animal or plant material in the soil. Bacteria and fungi consume organic matter and are, in turn, consumed by nematodes, protozoa, earthworms, collembola and some mite species. Nematodes and protozoa are consumed by some mites. Mites and collembola are eaten by beetles and ants. It is important to remember that the soil is a very complex habitat, in which the diversity of organisms is greater than that of the most diverse plant or animal community. This also means that it s not easy or accurate to generalize about all soil food web processes because the extent to which they occur will be different in different soils, at different times. The same processes (eg. mineralization) can be carried out by different groups of microorganisms. Soil Animals Soil animals are an extremely diverse group of organisms. Soil animals are grouped roughly according to their size, into three groups. The first group is the microfauna. These are the smallest of the soil animals ranging from 20 - 200 µm. The main soil animals in this group are protozoa. The mesofauna is the next largest group and range in size from 200 µm - 10mm. The most important animals in this group are mites, collembola (or spring tails) and nematodes. The macrofauna contain the largest soil animals such as earthworms, beetles and termites. Generally, the most common soil animals are protozoa, nematodes, mites and collembola.
eBook - PDF- A.B.R. Beemster, G.J. Bollen, M. Gerlagh, M.A. Ruissen, B. Schippers, A. Tempel(Authors)
- 2012(Publication Date)
- Elsevier Science(Publisher)
Studies on the biological and ecological aspects of certain Indian earthworms. Cited in: C.A. Edwards & K.E. Fletcher, 1988: Interactions between earthworms and micro-organisms in organic matter break-down. Agriculture, Ecosystems & Environment, 24: 235-247. Riffle, J.W., 1971. Effect of nematodes on root-inhabiting fungi. In: E. Hacskaylo (Editor), Mycorrhizae. U.S.D.A., for serra misc. Publ. 11891, 97-113. Rössner, J., 1981. Einfluss von Regenwürmern auf phytoparasitäre Nematoden. Nematologica, 27: 340-348. Rössner, J., & Urland, Κ., 1983. Mycophage Nematoden der Gattung Aphelenchoides an der Halmbasis von Getreidepflanzen und ihre Wirkung gegen Fusskrankheitserreger von Getreide. Nematologica, 29: 454-462. 19 Rouelle, J., 1983. Introduction of Amoebae and Rhizobium japonicum into the gut of Eisenia foetida (sav.) and Lumbricus terrestris . In: J.E. Satchell (Editor): Earthworm ecology, Chapman and Hall, London, 375-381. Shaw, P.J.H., 1988. A consistent hierachy in the fungal feeding preference of the collembola Onychiurus armatus . Pedobiologia, 31: 179-187. Schaerffenberg, B. & Trendl, Η., 1951. Untersuchungen über das Verhalten der Enchytraeiden gegenüber den Zuckerrüben-nematoden Heterodera schachtii (Schm.). Z. angew. Ent., 32: 476-488. Seastedt, T.R., 1984. The role of micr-arthropods in decomposition and mineralization process. Ann. Rev. Ent., 29: 25-46. Steiner, Η., El Titi, Α., & Bosch, J., 1986. Integrierter Pflanzenschutz in Ackerbau: Das Lautenbach Projekt I. Versuchsprogramm. Z. PflKrankh. PflSchutz., 93: 1-18. Storch, R.H., Frank, J.A. & Manzer, F.E., 1978. Fungi associated wiTh Collembola and mites isolated from scabby potatoes. American Potato Journal, 55: 197-201. Ulber, Β., 1980. Untersuchungen zum Nahrungswahl von Onychiurus fimatus Gisin (Onychiuridae, Collembola) , einem Aufgangsschädling der Zuckerrübe.
eBook - PDF- Urvashi Swami(Author)
- 2020(Publication Date)
- Delve Publishing(Publisher)
These swellings are referred to as elephantiasis. Other nematodes invent the human and animal stomach leading then to insufficient absorb nutrients. They can also destroy plants by boring some holes in the plant parts like the roots and stems. They can, in one way or the other, even cause a plant to dye. Most nematodes have very sharp mouths, and they can, therefore, suck the cell content in a plant when they bore the Soil-Borne Parasitic Worms 95 plant parts. Sucking of the cell content in the cell thus causes the death of the plant(Hotez et al, 2006). 5.3 IMPORTANCE OF EARTHWORMS 5.3.1 Earthworms help Improve the Nutrient Availability Earthworms eat as they extract nutrients by burrowing of materials such as plants and debris or by dragging materials from plants into the burrows. Some bacteria and nutrients are produced when earthworms leave waste products through burrowing. There are three types of burrowing; • Horizontal burrowing that contains shafts that are occasional into the soil. • There is deep vertical burrowing which has a surface with many branch entries. • The vertical burrows that are formed by the earthworms living in the soil. The dead organic matter gets decomposed into nutrients that are important to the life of the plants. For example, earthworms decompose dead animals until they cannot be seen. The bodies of worm always decompose leading to soil rich in Nitrogen. The worm pile is said to be releasing four times more phosphorus than the soil can do. Earthworms usually leave the tunnels of their worm pile that are rich in nutrients hence leaves the soil suitable for plant growth (Hotez et al, 2006). Figure 5.2: The earthworm cast. Source: https://www.sciencelearn.org.nz/resources/9-earthworms-role-in-the-ecosystem Soilborne Pathogens 96 Soil worms show a significant impact on the soil microbial community and increment nitrogen mineralization in soil.
eBook - PDF- Gupta, Rajan Kumar(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
These activities change the soils physico-chemical and biological status and may cause drastic shifts in the density, diversity, structure and activity of microbial and faunal communities within the drilosphere. Certain organisms and species may be enhanced, reduced or not be effected at all depending on their ability to adapt to the particular conditions of different earthworm drilospheres. A large host of factors (including CaCo 3 , enzymes, mucus and antimicrobial substances) influence the ability of preferentially or randomly ingested organisms to survive (or not) passage through the earthworm gut, and their resultant capacity to recover or proliferate (or not) in earthworm casts. Long before the invention of agricultural implements, earthworms ploughed the soil, mixing, tilling and building topsoil as they burrowed through the earth. Their importance has been clearly recognized for nearly This ebook is exclusively for this university only. Cannot be resold/distributed. 200 years, and even in the Fourth Century B.C., Aristotle, it is said, aptly referred to earthworms as “the intestines of the earth” though he may well have been referring to their appearance rather than to their function. But what do we know about these animals? The following will help us to understand earthworms and how we may be able to benefit from their activities. Taxonomy Earthworms are scientifically classified as animals belonging to the order Oligochaeta, class Chaetopoda, phylum Annelida. In this phylum there are about 1,800 species of earthworms grouped into five families and distributed all over the world (Lee, 1985). The most common worms in North America, Europe, and Western Asia belong to the family Lumbricidae, which has about 220 species. Only a few types are of interest to the commercial earthworm grower, and of these only two are raised on a large-scale commercial basis.
eBook - PDF- Clive A. Edwards(Author)
- 2004(Publication Date)
- CRC Press(Publisher)
146 Earthworm Ecology, Second Edition The contributions of earthworms to soil fertility have been described in several hundreds of articles and books (Lee 1985; Edwards and Bohlen 1996; Lavelle and Spain 2001). This has led to a growing expectation from soil users for provision of methods that protect soil fertility through the enhancement of biological processes. Earthworms may be considered a biological resource for farming systems, and the management of earthworm communities provides a promising Þ eld for innovation in agricultural practices (Lavelle et al. 1999). Demand for techniques, making optimal use of earthworms as a resource, is likely to increase, although basic research is still needed to support such developments. The relationships between earthworm activities and changes in soil properties are not thoroughly understood, especially at large timescales of years to decades. Most research results have been obtained in small-scale laboratory or Þ eld experiments that exaggerate the process under study and can by no means be extrapolated readily to larger scales of time and space. However, recent research on earthworm casts and other related biogenic structures have shown that these structures may persist for rather long periods and provide the soil with speci Þ c properties that may survive the death and elimination of earthworm populations that produced them. This property contributes signi Þ cantly to the resistance and resilience of soils to disturbances (Lavelle et al. 2004). This chapter synthesizes information on the effects of earthworms on soil systems at scales longer than 1 year, and earthworm behavior that may affect these processes is detailed.
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