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The potential contribution of regolith to nutrient supply for Eucalyptus plantations in KwaZulu-Natal, South Africa
Thesis (PhDAgric)--Stellenbosch University, 2026.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2026
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| _version_ | 1869484249336250368 |
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| access_status_str | Open Access |
| author | Cooper, Glen David |
| author2 | Rozanov, Andrei |
| author_browse | Cooper, Glen David Rozanov, Andrei |
| author_facet | Rozanov, Andrei Cooper, Glen David |
| author_sort | Cooper, Glen David |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhDAgric)--Stellenbosch University, 2026. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/135699 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-07-01T04:11:53.517Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/135699 The potential contribution of regolith to nutrient supply for Eucalyptus plantations in KwaZulu-Natal, South Africa Cooper, Glen David Rozanov, Andrei Burgdorf, Richard Morris, Andrew Stellenbosch University. Faculty of AgriSciences. Dept. of Soil Science. Eucalyptus -- Nutrition -- South Africa -- KwaZulu-Natal Regolith Plant nutrients -- South Africa -- KwaZulu-Natal Soils and nutrition Plant-soil relationships -- South Africa -- KwaZulu-Natal Sustainable forestry -- South Africa -- KwaZulu-Natal Soil mineralogy Nutrient cycles UCTD Thesis (PhDAgric)--Stellenbosch University, 2026. Cooper, G. D. 2026. The potential contribution of regolith to nutrient supply for Eucalyptus plantations in KwaZulu-Natal, South Africa. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/af7e46bf-2b6e-48f8-950c-947ff36297c8 ENGLISH ABSTRACT: The regolith is a key component of the Critical Zone and integral to maintaining the supply of water and nutrients to forest ecosystems. The deep regolith has been shown to contribute to nutrient supply in arid and temperate forest systems. However, it has received limited attention regarding eucalypt plantations. Previous research on plantation nutrient supply has focused on the upper soil (<1m depth), where additions from fertilization, litter mineralization, and atmospheric inputs are easily accounted for. Eucalyptus spp. are deep-rooting and have been shown to rapidly develop a large mass of fine roots to depths of several meters when nutrient and water demand is high. This study aimed to assess the potential of the entire regolith profile to supply phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) to eucalypt plantations in a South African context. To achieve this, five regolith profiles were sampled from two transects on contrasting lithologies: a Natal Group sandstone and a Dwyka tillite. The entire profile was sampled using rotary core drilling at the crest and mid-slope positions of each transect, and a fifth profile from a dolerite intrusion on the sandstone mid-slope. These profiles were described by their degree of weathering, rooting presence, and mineralogical and chemical characteristics. Both topography and parent material influenced the formation of the regolith, with the deepest in-situ weathering at the crest positions, while the mid-slopes were influenced by transported materials. The deepest profiles were the sandstone crest (24.0 m), tillite mid-slope (18.0 m), and dolerite mid-slope (15.4 m), while the tillite crest (8.2 m) and sandstone mid-slope (6.2 m) were shallowest. The densest rooting was in the upper 0.5 – 0.7 m of the profiles; however, fine rooting was observed to depths of < 5 m. Parent material and profile depth influenced the available nutrient stocks, with large stocks of P. K and Ca in the subsoil and saprolite horizons. At the shallowest profiles, the largest proportion of nutrient were in the saprolite and saprock. The tillite profiles had the largest stocks of P, Ca, and Mg, while the dolerite profile had the largest of K. A pot trial to assess the bioavailability of nutrients from different regolith horizons found that the tillite had the greatest bio-availability of the lithologies. Within each lithology, the soil horizons were shown to have the greatest nutrient availability. All substrates were found to have a limited supply of P, K, and Ca. A simulation of nutrient loss at harvest illustrated that P and K were susceptible to depletion with increased biomass removal. The inclusion of available nutrient stocks from within the entire observed rooting depth was found to increase the sustainability of the site. It was found that there were large stocks of available nutrients within the deeper regolith horizons. The presence of rooting activity within these horizons suggests that they play a key role in meeting the nutrient demand of eucalypt plantations, most importantly during early establishment. AFRIKAANSE OPSOMMING: Die regoliet is ’n sleutelkomponent van die Kritieke Sone en is integraal tot die handhawing van die voorsiening van water en voedingstowwe aan bosekosisteme. Daar is getoon dat diep regoliet ’n beduidende bydrae lewer tot voedingstofvoorsiening in beide droë en gematigde woudstelsels; dit het egter beperkte aandag in eukaliptusplantasies ontvang. Vorige navorsing oor voedingstofvoorsiening in plantasies het hoofsaaklik op die boonste grondlaag (< 1 m diepte) gefokus, waar insette vanuit bemesting, strooiselmineralisasie en atmosferiese neerslag makliker gekwantifiseer kan word. Eucalyptus spp. is diepwortelend en kan vinnig ’n aansienlike massa fyn wortels tot op dieptes van verskeie meter ontwikkel wanneer die vraag na water en voedingstowwe hoog is. AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die potensiaal van die volledige regolietprofiel te evalueer om fosfor (P), kalium (K), kalsium (Ca) en magnesium (Mg) aan eukaliptusplantasies in ’n Suid-Afrikaanse konteks te voorsien. Vyf regolietprofiele is langs twee transekte op kontrasterende litologieë bemonster: Natalgroep-sandsteen en Dwyka-tilliet. Profiele is deur middel van roterende kernboring by kruin- en middelhellingposisies op elke transek verkry, met ’n addisionele profiel wat vanaf ’n dolerietintrusie op die sandsteen-middelhelling bemonster is. Elke profiel is beskryf ten opsigte van verweringsgraad, wortelteenwoordigheid, asook mineralogiese en chemiese eienskappe. Beide topografie en moedermateriaal het die ontwikkeling van die regoliet beïnvloed. Die diepste in situ-verwering is by die kruinposisies waargeneem, terwyl middelhellingprofiele tekens van getransporteerde materiaal getoon het. Die diepste profiele was die sandsteen-kruin (24,0 m), tilliet-middelhelling (18,0 m) en doleriet-middelhelling (15,4 m). Daarteenoor was die tilliet-kruin (8,2 m) en sandsteen-middelhelling (6,2 m) die vlakste. Worteldigtheid was die hoogste in die boonste 0,5–0,7 m; fyn wortels is egter tot op dieptes van tot 5 m waargeneem. Moedermateriaal en profieldiepte het ’n sterk invloed op beskikbare voedingstofvoorrade gehad. Aansienlike reserwes van P, K en Ca was in die ondergrond- en saproliethorisonte teenwoordig. In die vlakste profiele was die grootste proporsie voedingstowwe in die saproliet en saproklip gekonsentreer. Die tillietprofiele het die grootste voorrade van P, Ca en Mg bevat, terwyl die dolerietprofiel die grootste K-voorraad gehad het. ’n Potproef om die biobeskikbaarheid van voedingstowwe uit verskillende regoliethorisonte te evalueer, het getoon dat tilliet die hoogste algehele biobeskikbaarheid onder die litologieë gehad het. Binne elke litologie het die grondhorisonte die hoogste voedingstofbeskikbaarheid getoon. Nieteenstaande hierdie verskille het alle substrate beperkte voorrade van P, K en Ca getoon. ’n Simulasie van voedingstofverlies tydens oes het getoon dat P en K besonder vatbaar is vir uitputting met verhoogde biomassa-verwydering. Die insluiting van beskikbare voedingstofvoorrade vanuit die volle waargenome worteldiepte het die volhoubaarheid van die terrein aansienlik verbeter. Oor die algemeen is groot voorrade beskikbare voedingstowwe in die dieper regoliethorisonte geïdentifiseer. Die teenwoordigheid van aktiewe wortels in hierdie sones dui daarop dat hulle ’n belangrike rol speel in die voldoening aan die voedingstofbehoefte van eukaliptusplantasies, veral tydens vroeë vestiging Doctoral 2026-04-08T08:18:29Z 2026-04-08T08:18:29Z 2026-03 Thesis https://scholar.sun.ac.za/handle/10019.1/135699 en Stellenbosch University xvi, 229 pages : illustrations, maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Eucalyptus -- Nutrition -- South Africa -- KwaZulu-Natal Regolith Plant nutrients -- South Africa -- KwaZulu-Natal Soils and nutrition Plant-soil relationships -- South Africa -- KwaZulu-Natal Sustainable forestry -- South Africa -- KwaZulu-Natal Soil mineralogy Nutrient cycles UCTD Cooper, Glen David The potential contribution of regolith to nutrient supply for Eucalyptus plantations in KwaZulu-Natal, South Africa |
| title | The potential contribution of regolith to nutrient supply for Eucalyptus plantations in KwaZulu-Natal, South Africa |
| title_full | The potential contribution of regolith to nutrient supply for Eucalyptus plantations in KwaZulu-Natal, South Africa |
| title_fullStr | The potential contribution of regolith to nutrient supply for Eucalyptus plantations in KwaZulu-Natal, South Africa |
| title_full_unstemmed | The potential contribution of regolith to nutrient supply for Eucalyptus plantations in KwaZulu-Natal, South Africa |
| title_short | The potential contribution of regolith to nutrient supply for Eucalyptus plantations in KwaZulu-Natal, South Africa |
| title_sort | potential contribution of regolith to nutrient supply for eucalyptus plantations in kwazulu natal south africa |
| topic | Eucalyptus -- Nutrition -- South Africa -- KwaZulu-Natal Regolith Plant nutrients -- South Africa -- KwaZulu-Natal Soils and nutrition Plant-soil relationships -- South Africa -- KwaZulu-Natal Sustainable forestry -- South Africa -- KwaZulu-Natal Soil mineralogy Nutrient cycles UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/135699 |
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