Earthworms as bioindicators of soil health in a conservation agriculture setting in the Western Cape

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dc.contributor.advisorRoets, Francoisen_ZA
dc.contributor.advisorStrauss, Johannen_ZA
dc.contributor.advisorNxele, Thembekaen_ZA
dc.contributor.authorSteyl, An-Marien_ZA
dc.contributor.otherStellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.en_ZA
dc.date.accessioned2023-03-06T08:17:08Z
dc.date.accessioned2023-05-18T07:16:02Z
dc.date.available2023-03-06T08:17:08Z
dc.date.available2023-05-18T07:16:02Z
dc.date.issued2023-03
dc.descriptionThesis (MScConsEcol)--Stellenbosch University, 2023en_ZA
dc.description.abstractENGLISH ABSTRACT: Adopting conservation agriculture (CA) principles aims to increase crop production while improving overall soil health. One benefit of adopting these principles is increased biological activity, such as earthworms. Earthworms are essential soil ecosystem engineers and sensitive to management practices, making them suitable as potential soil health indicators. Since conservation agriculture could promote the numbers and activity of earthworms, they can most likely be used as soil health indicators in these systems. However, this has received very little attention in the Mediterranean climatic region of the Western Cape province. This study assessed whether conservation agricultural practices increase earthworm populations and whether earthworms have the potential to be used as indicators of soil health in these systems. The study was based on two experimental farms in the Western Cape province, each with a mixture of different CA crop rotations, varying levels of legume incorporation, and two conventional tillage sites used as controls. Earthworm samples were collected using three different sampling techniques: hand-sorting, mustard extraction and a combination of the two methods during four sampling stages based on crop growing season. The influence of the sampling method, sampling stage and farming system on earthworm abundance and generic richness was tested. Earthworm abundance and generic richness were also correlated against different soil variables to investigate whether earthworms can be indicators of soil health parameters. The hand-sorting method proved sufficient for obtaining a good representation of earthworm fauna in these systems. CA practices, even those with increased utilization of legume crops, did not necessarily benefit earthworm populations. However, a strong link between soil moisture, earthworm abundance, and generic richness appears to be the most crucial factor driving earthworm numbers in this dry region. Furthermore, earthworm abundance only correlated with a few soil variables, indicating that earthworms could potentially not be useful as indicators of soil health in this region. The exception was a strong correlation between earthworm abundance and soil organic carbon content, indicating that earthworms could be used to indicate this agriculturally important soil variable. Based on this study's results, practices that conserve water and increase carbon content in the soil will likely increase earthworm populations in this region and improve the services they provide.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Die toepassing van bewaringslandbou praktyke beoog om gewas produksie asook algemene grondgesondheid te bevorder. Deur die toepassing van hierdie praktyke kan biologiese aktiwiteit van organisms soos erdwurms vermeerder word. Erdwurms speel ‘n noodsaaklike rol in die grond en is baie sensitief vir boerdery bestuurspraktyke, daarom het hulle die potensiaal om as bioindikators vir grondgesondheid gebruik te word. Bewaringslandbou kan erdwurm getalle bevorder in die grond wat hulle geskik maak as moontlike bioindikators in hierdie stelsels. Tot dusver is daar ‘n tekort aan navorsing hieroor in die Mediterreense klimaat van die Wes-Kaap. Die doel van hierdie studie was om te bepaal of bewaringslandbou praktyke erdwurm populasies vermeerder en of erdwurms kan gebruik word as bioindikators in hierdie stelses. Die studie het plaasgevind op twee proefplase in die Wes-Kaap, elk met ‘n mengsel van bewaringslandbou gewas rotasies, verskillende vlakke van peulgewas inkorporering en twee konvensionele ploeg persele wat as kontroles gedien het. Erdwurms was versamel deur gebruik te maak van drie verskillende metodes, hand-sortering, ‘n mostert oplossing en ‘n kombinasie van die twee metodes Dit was gedoen oor vier verskillende stadiums van die jaar gebaseer op die groei seisoen. In die studie was die invloed van versamel metode, versamel tydperk en plaas stelsel op erdwurm getalle en diversiteit getoets. Erdwurm getalle en diversiteit was ook getoets vir korrelasies met ander grondfaktore om te bepaal of hulle gebruik kan word as bioindikators vir hierdie faktore. Die hand- sorteer metode was effektief genoeg om ‘n goeie verteenwoordiging van erdwurms te versamel in hierdie stelsels. Die bewaringslandbou praktyke, insluitende dié met hoër benutting van ‘n peulgewas, het nie noodwendig die erdwurm populasies bevoordeel nie. Inteendeel, daar was ‘n sterker korrelasie tussen grondvog inhoud en die erdwurm getalle en diversiteit. Dit is dus ‘n beduidende faktor wat erdwurm getalle dryf in hierdie droë area. Erdwurm getalle het ook net met ‘n paar grondfaktore gekorreleer wat aandui dat hul potensieël nie geskik is as bioindikators in hierdie area nie. Daar was wel ‘n sterk korrelasie tussen erdwurm getalle en organiese koolstof inhou, wat aandui dat dit die potensiaal het om gebruik te word as indikator vir hierdie belangrike grondfaktor. Na aanleiding van die resultate van hierdie studie kan enige praktyke wat grondvog bewaar en koolstof inhoud vermeeder moontlik erdwurm populasies vermeerder en so ook die ekosisteem dienste wat hulle verskaf in die grond verseker.af_ZA
dc.description.versionMastersen_ZA
dc.format.extentx, 65 pages : illustrations (some color), mapsen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/127322
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subjectbioindicators, conservation agriculture, earthworms, soil healthen_ZA
dc.subject.lcshEarthworms -- Ecology -- South Africa -- Western Capeen_ZA
dc.subject.lcshConservation agriculture -- South Africa -- Western Capeen_ZA
dc.subject.lcshIndicators (Biology)en_ZA
dc.subject.lcshBioindicatorsen_ZA
dc.subject.lcshSoils -- Carbon contenten_ZA
dc.subject.lcshSoil healthen_ZA
dc.subject.nameUCTDen_ZA
dc.titleEarthworms as bioindicators of soil health in a conservation agriculture setting in the Western Capeen_ZA
dc.typeThesisen_ZA
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Masters Degrees (Conservation Ecology and Entomology)