Thesis (MScAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: This study is an integral part of a multidisciplinary research project concerning the effects of soil and climate on wine quality. The motive, which led to the setting up of this project, was that producers could not determine beforehand whether a specific location would yield wines of high or low quality. If a specific cultivar were to be planted at the wrong location, then it was likely that wine of table quality would result, rather than the export quality wine that was intended. The long term objectives of this multidisciplinary project were the compilation of guidelines by means of which different sites may be classified according to their potential for the production of high quality wines, and the identification of the most important climatic and soil factors responsible for differences in wine quality and character. In this multidisciplinary project, measurements (soil water, leaf water potential, cane mass and yield) were made under dry land conditions in Sauvignon blanc vineyards at six different localities: five in the Stellenbosch district (Simonsberg, Kuils River, Helshoogte, Papegaaiberg and Devon Valley) and one in Durbanville. Each vineyard was owned by a private commercial producer. The vines were approximately 10 years old in all cases, and were trained on a hedge system. Measurements were made in plots, each of which contained 20 vines. Two different soil types were identified at each locality. Vine growth and wine quality differed markedly on these contrasting soils, even though they were located in close physical proximity. The measurements that were made at high and low production plots at each locality during this study were obtained from points which were not more than 60 m metres apart. An automatic weather station was erected halfway between the two, contrasting, experimental plots. Within the overall scope of the multidisciplinary project, the study which forms the subject of this thesis, concentrated on the effects of soil parent material as a soil forming parameter and as a possible predetermining character with regard to vine growth and wine character. From literature it was clear at the outset of this work that the geology of the coastal wine region is very complex and varies over short distances. The geological history indicates different types of rock formation and rock forming process (sedimentary, igneous as well as metamorphic), plate tectonic activity, mountain building, erosion and weathering, over a period of approximately 1 000 million years. The present landscape includes a coastal plane, hills, and eroding mountains. Statistical analyses indicated that the soils from the different localities could mainly be characterised in terms of differences in their sand size fractions. Soils from Durbanville are dominated by fine sand and correlates with the underlying phyllitic shales. Soils from Kuils River contain significantly more coarse sand when compared with the other sites. This appears to be a reflection of the underlying coarse granitic material, and implies that in situ weathering played an important role in soil development. .The data did not, however, prove that the Kuils River soils formed solely from underlying rocks. The gravel and stone fraction for the Kuils River soils were nevertheless correlated with those of the underlying parent material. Soils from Helshoogte and Simonsberg (both of which are underlain by granites), Papegaaiberg and Devon Valley (both underlain by hornfels) were not significantly dominated by any particular sand fraction. Soils from these localities therefore did not only reflect the underlying material as a source of soil parent material. This implied mixing of parent material and/or the incursion of eolian sand at Helshoogte, Simonsberg and Devon Valley. A marine incursion may have affected the soil parent material at Papegaaiberg. In order to obtain more information concerning the origins and possible mixing of parent materials prior to and during soil formation, samples from the different soil horizons in each profile were subjected to a chemical analysis. Particular emphasis was placed on potassium, which is an extremely important nutrient mineral element, from the viewpoints of vine growth and wine quality. Because the soils used in this study were all located in production vineyards, the probability that fertiliser residues would have contaminated the soils was high. The lower soil horizons were considered to be least affected by this contamination and therefore most likely to be indicative of the natural soil chemical composition. However, the lower horizon K content of the soils in this study could not be reliably correlated with any known or predicted characteristic that might link the soil parent material with local rock types. At Durbanville, both soils contained small quantities of K in the lower horizons, reflecting the underlying phyllitic shales, but at Devon Valley and Papegaaiberg, the lower horizons contained more K than expected. The soils at these localities are situated on hornfels, containing low quantities of K. The large quantities of K in the soils may have indicated that these soils are situated close to a granite/Malmesbury contact zone. Soils from Kuils River, Simonsberg and Helshoogte are situated on K-rich porhyritic granites and it was expected that these soils would contain relatively large quantities of K in the lower horizons. This, however, was not the case. It was therefore concluded that dilution with K-poor material had taken place. Such material could have been derived from higher-lying sandstones, or from eolian processes during the Cenozoic. Alternatively, the K content of the soil might have been depleted by long continued leaching. A semi-quantitative analysis of the minerals in the soil clay fractions was also carried out. The objective was to identify the clay minerals that were present in the different soil horizons and to relate the minerals to weathering conditions. Evidence linking the minerals in the clay fractions of the soil samples with the mineralogical composition of the soil parent materials was sought. The clay fraction mineralogy data indicated that all soils in the study area are in an advanced stage of weathering and are dominated by kaolinite, and in certain soils quartz. It was difficult to relate these minerals directly with soil parent material because the primary minerals originating from the soil parent materials have been extensively broken down. The simultaneous presence of quartz and gibbsite in the clay fraction of both soils at Simonsberg, Helshoogte and Durbanville as well as one soil form from bath Kuils River and Simonsberg, indicated non-uniform distribution of clay fraction minerals, indicating that different stages of weathering were present during soil formation. This could have been a result of mixing of parent materials, but may also reflect different periods of weathering of the same material. Both soils at Papegaaiberg, both soils at Devon Valley and other soils at Simonsberg and Kuils River indicated uniform clay fraction mineralogy distribution, mainly because the absence of gibbsite is related to the presence of quartz in the clay fraction. The soil characteristics, as determined in this study, were also compared with vine growth, wine quality and wine character, as obtained in the broader multidisciplinary research project. For most soils in this study, an increase in clay fraction kaolinite was associated with a reduction in vegetative growth, overall wine quality, and fresh vegetative character. An increase in clay fraction quartz was associated with higher overall wine quality. Increased shoot growth also affected fresh vegetative character positively. Better growth occurred on higher altitudes and this resulted, for Sauvignon blanc, in higher wine quality. Wines produced from vines situated on both phyllitic shales and porhyritic granites showed high quality (Durbanville and Helshoogte), but both were related to low clay fraction kaolinite content and high altitude. It was not possible to relate parent material directly with vine growth, wine quality and/or wine character. The lowest quality wines, however, were produced from vines situated on hornfels (Papegaaiberg and Devon Valley), both containing high quantities of clay fraction kaolinite and situated on low altitudes. High levels of K in soils containing high levels of clay fraction kaolinite may have been partly responsible for low wine quality obtained on such soils. / AFRIKAANSE OPSOMMING: Hierdie studie vorm 'n integrale deel van 'n multi-dissiplinêre navorsingsprojek oor die effek van grond en klimaat op wynkwaliteit. Die motivering wat gelei het tot die beplanning van hierdie projek, was dat produsente nie vooraf kon bepaal of 'n spesifieke lokaliteit wyne kan produseer van hoë of lae kwaliteit nie. Indien 'n spesifieke kultivar op die verkeerde lokaliteit geplant word, sou dit waarskynlik tot In gewone tafelwyn lei, instede van 'n wyn van uitvoergehalte. Die langtermyn doelwitte van die multi-dissiplinêre projek was om riglyne te ontwikkel om verskillende lokaliteite te klassifiseer na aanleiding van·hul potensiaal om hoë kwaliteit wyne te produseer, asook om die belangrikste klimaats- en grondfaktore verantwoordelik vir die produksie van hoê kwalitiet wyne te identifiseer. In hierdie multidissiplinêre projek was metings (plant beskikbare water, blaarwater potensiaal, lootmassa en oes) onder droêland toestande bepaal in Sauvignon blanc wingerde by ses verskillende lokaliteite: vyf in die Stellenbosch distrik (Simonsberg, Kuilsrivier, Helshoogte, Papegaaiberg and Devon Valley) en een in Durbanville. Elke wingerd is besit deur 'n kommersiêle privaatprodusent. Die stokke was ongeveer 10 jaar oud in alle gevalle en opgelei op 'n heining sisteem. Metings was in eksperimentele blokke van 20 stokke elk uitgevoer. Twee verskillende grondtipes is by elke lokaliteit identifiseer. Lootgroei en wynkwaliteit het merkbaar verskilop die kontrasterende gronde, selfs waar gronde nabyaanmekaar was. Die metings is Liitgevoer op hoë- en lae produksie eksperimentele blokke waar gronde by spesifieke lokaliteite nie verder as 60 meter was nie. 'n Outomatiese weerstasie was halfpad tussen die twee kontrasterende grondtipes by elk van die ses lokaliteite opgerig. Binne die algemene omvang van die multi-clissiplinêre projek, het die studie wat die onderwerp van hierdie tesis is, gekonsentreer op die effek van moedermateriaal as grondvormende parameter asook as moontlike voorspeller van wingerdgroei en wynkarakter. Dit was duidelik uit die literatuur dat die geologie van die Wynkusstreek baie kompleks is en oor kort afstande varieer. Die geologiese geskiedenis dui daarop dat verskillende tipes gesteentes en verskillende prosesse van gesteente-vorming (sedimentêr, stollings- en metamorfe), plaattektoniese aktiwiteit, orogenese, erosie en verwering, oor 'n periode van ongeveer 1 000 miljoen jaar plaasgevind het. Die huidige landskap sluit kusvlaktes, heuwels en geêrodeerde berge in. Statistiese analises het aangetoon dat die gronde van die verskillende lokaliteite hoofsaaklik in terme van verskille in sandgrootte fraksies onderskei kon word. Gronde van Durbanville is gedomineer deur fyn sand en korreleer met onderliggende fillietiese skalies. Gronde van Kuilsrivier bevat betekenisvol meer growwe sand wanneer dit vergelyk word met die ander lokaliteite. Dit is waarskynlik afkomstig vanaf die onderliggende growwe granitiese materiaal en impliseer dat in situ verwering 'n belangrike rol gespeel het in grondontwikkeling. Die data het egter nie bewys dat die gronde van Kuilsrivier slegs uit die onderliggende graniete gevorm het nie. Die gruisfraksies in die gronde by Kuilsrivier was tog vergelykbaar met die onderliggende materiaal. Gronde vanaf Helshoogte and Simonsberg (beide onderlê deur graniete), Papegaaiberg and Devon Valley (beide onderlê deur hornfels) was nie betekenisvol gedomineer deur 'n spesifieke sandfraksie nie. Gronde vanaf hierdie lokaliteite het dus nie slegs die onderliggende gesteentes verteenwoordig nie. Dit dui op vermenging van moedermateriaal en/of eoliese prosesse by Helshoogte, Simonsberg and Devon Valley. 'n Styging in seevlak kon die moedermateriaal by Papegaaiberg beïnvloed het. Om meer inligting omtrent die oorsprong en moontlike vermening van moedermateriaal voor grondvorming te verkry, is die verskillende grondmonsters chemies ontleed. Kalium is In uiters belangrike voedingselement wat lootgroei en wynkwaliteit kan beïnvloed. Aangesien die gronde in hierdie studie in bestaande produksieblokke voorkom, was daar 'n goeie kans dat bemestingstowwe die chemiese samestelling kon beïnvloed. Die C horisonte van die verskillende gronde was beskou as dié wat die minste deur bemesting beYnvloedsou word en die naaste aanduiding van natuurlike grondchemiese samestelling. Die C horison K-inhoude van die gronde in die studie het egter nie gekorreleer met enige eienskap wat die moedermateriaal van die gronde met die lokale gesteentetipe kon verbind nie. By Durbanville, het beide gronde klein hoeveelhede K in die C horisonte bevat, wat die onderliggende fillietiese skalies reflekteer, maar by Devon Valley en Papegaaiberg, het die C horisonte meer K bevat as wat verwag is. Die gronde by hierdie lokaliteite word onderlê deur hornfels, wat lae hoeveelhede K bevat. Die groot hoeveelhede K in hierdie gronde dui moontlik op 'n kontaksone tussen graniet en Malmesbury gesteentes in die area. Gronde vanaf Kuilsrivier, Simonsberg en Helshoogte word onderlê deur K-ryke porfiritiese graniete wat groot hoeveelhede K in die ondergronde sou bevat. Dit was egter nie die geval nie en dit was aanvaar dat verdunning van K-arme materiaal plaasgevind het. Die oorsprong van Karme materiaal was waarskynlik vanaf hoêr-liggende sandstene, of vanaf eoliese prosesse gedurende die Cenozoikum. Alternatiewelik is K inhoude van die gronde verlaag deur lang en aanhoudende loging. 'n Semi-kwantitatiewe analise van minerale in die kleifraksie was uitgevoer om te bepaal watter minerale in die kleifraksie van die verskillende gronde teenwoordig is en om die minerale met stadia van verwering te vergelyk. Dan kon die mineralogiese samestelling in verband met moedermateriaal gebring word. Resultate het aangetoon dat al die gronde in die studie in 'n gevorderde stadium van verwering is en gedomineer word deur kaoliniet, en in sekere gronde, klei fraksie kwarts. Aangesien die primêre minerale in 'n groot mate afgebreek is, was dit moeilik om die minerale in die kleifraksie direk in verband met moedermateriaal te bring. Die voorkoms van kwarts en gibbsiet in die kleifraksie in beide gronde van Simonsberg, Helshoogte en Durbanville asook een grondvorm vanaf beide Kuilsrivier en Simonsberg, het aangetoon dat verskillende stadia van verwering gedurende grondvorming in hierdie gronde voorgekom het. Dit kan die gevolg wees van vermenging van verskillende moedermateriaal, maar kan ook verskillende periodes van verwering van dieselfde materiaal aandui. Beide gronde by Papegaaiberg, beide gronde van Devon Valley die ander gronde by Simonsberg en Kuilsrivier het slegs een fase van verwering tydens grondvorming aangedui, hoofsaaklik as gevolg van die afwesigheid van gibbsiet wanneer kwarts voorkom. Grondeienskappe, soos bepaal in hierdie studie, was ook vergelyk met lootgroei, wynkwaliteit en wynkarakter, soos verkry uit die resultate van die multi-dissiplinêre projek. Vir die meeste gronde in die studie was 'n toename in kleifraksie kaoliniet geassosieer met afname in vegetatiewe groei, algemene wynkwaliteit, asook vars vegetatiewe wynkarakter. 'n Toename in kleifraksie kwarts was geassosieer met hoër algehele wynkwaliteit. 'n Toeneme in vegetatiewe groei het ook die vars vegetatiewe karakter van die wyn positief beïnvloed. Beter vegetatiewe groei het op hoër hoogtes voorgekom en dit het gelei tot hoër wynkwaliteit vir Sauvignon blanc. Wyne afkomstig van wingerde op beide fillietiese skalies en porfiritiese graniete, was van hoër kwaliteit (Durbanville and Helshoogte), maar beide was geassosieer met lae kleifraksie kaoliniet en hoë ligging. Dit was nie moontlik om moedermateriaal direk met vegetatiewe groei, wynkwaliteit en/of wynkarakter te vergelyk nie. Wyne met die laagste kwaliteit kom egter voor op hornfels (Papegaaiberg and Devon Valley), wat beide groot hoeveelhede kleifraksie kaoliniet bevat en geleê is op lae hoogtes. Hoê vlakke van K in gronde wat groot hoeveelhede kleifraksie kaoliniet bevat kan gedeeltelik verantwoordelik wees vir lae kwaliteit wyne op sulke gronde.

Thesis (MScAgric (Soil Science))--University of Stellenbosch, 2005. / This thesis forms part of a research program that is investigated by ARC Infruitec- Nietvoorbij and the University of Stellenbosch. The aim of this program is to quantify the effect of soil and climate on wine quality and character as a basis for scientific demarcation of production regions. Natural factors are first quantified and characterised so that relative homogeneous natural terroir units (NTU) can be identified. Thereafter wines made from these different localities are assessed for similarities which permit grouping of localities into viticultural terroirs. The present study involved seven research plots in the Robertson district, making use of initial measurements by ARC Infruitec-Nietvoorbij in the 2000/01 and 2001/02 seasons together with more intensive measurements in the 2002/03 and 2003/04. The seven plots are located in two wards, Le Chasseur and Vinkrivier. Sauvignon blanc plots were marked at two localities, each with two sub-plots occurring in one block. Three Cabernet Sauvignon plots were marked out. Two plots occurred in one block in Le Chasseur and one plot in Vinkrivier. Plots within the same block were located on different soil types so that the effect of soil type on wine quality and character could be monitored. Morphological examination of soil profiles at each plot was carried out together with physical and chemical analysis of samples taken at 30cm depth intervals. Soil water content was measured at regular intervals to assess soil water tension. Vineyard performance was assessed in terms of phenology, root system studies, leafwaterpotential measurements, canopy quality assessment, leaf analysis, shoot growth, and data relating to ripening, harvest and pruning. Wines were made from each plot by ARC Infruitec- Nietvoorbij and evaluated by a tasting panel after six months and then again after eighteen months. Meteorological data were collected in each ward.

Thesis (MscAgric (Viticulture and Oenology))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Little scientific information regarding the effect of different geological parent materials on grapevine performance is currently available in South Africa. This aspect is of special significance for the Helderberg area, where parent material may change from granite to shale over a short distance. This results in shale- as well as granite-derived soils often occurring within the same vineyard. The objectives of this study were to (i) quantify the nutritional status and other soil properties of different parent materials (shale and granite) and overlying soils (ii) investigate the impact of geological differences in the soil on the vine nutritional status and certain vine parameters. This study was done over two seasons (2006/2007 and 2007/2008). Two Sauvignon blanc and two Cabernet Sauvignon vineyard blocks were selected at two different localities for each cultivar in the Helderberg area, South Africa. Shale- and granitederived soils were identified within each block. Kaolinite was the dominant mineral, whereas quartz and feldspar were sub-dominant. Traces of mica were also present in some shale- and granite-derived soils. Granite- contained significantly higher contents of coarse sand than shale-derived soils, whilst the opposite occurred in terms of fine sand. These differences affected the water holding capacity, in general making it higher in shale- than granite-derived soils. Shale-derived soils had higher concentrations of total K but granite-derived soils had a higher ability to release K as they contained higher concentrations of soluble K. The Q/I parameters, potential buffering capacity of K (PBCK) and equilibrium activity ratio of K (ARK) showed no consistent responses to geological differences. Potassium concentrations were higher in the leaf blades (obtained before harvest in 2007) from Sauvignon blanc grapevines on granite- than on shale-derived soils. Potassium concentrations in the Cabernet Sauvignon juice (obtained in 2007) tended higher in juice from granite- than from shale-derived soils. In 2008, K concentrations tended higher in juice from shale- than from granite-derived soils for both cultivars. The pH of the Sauvignon blanc juice (obtained in 2008) tended higher in juice from shale-than from granite-derived soils, thus corresponding with the K concentrations in the juice in this season. Nitrogen concentrations were higher in Cabernet Sauvignon juice (obtained in 2007) and Sauvignon blanc juice (obtained in 2008) from shalethan from granite-derived soils. In terms of vine water status, vines on granite-derived soils appeared more stressed than those on shale-derived soils in both seasons at one of the vineyards. In these Sauvignon blanc and Cabernet Sauvignon vineyards, the K nutritional status was not affected by geology in a consistent manner but there were some noticeable tendencies for a specific cultivar during certain seasons. On account of vines being planted on shale- and granite-derived soils within the same block, soil preparation was done similarly for both soils, and they were exposed to similar irrigation schedules, canopy management strategies and climatic conditions. Therefore, there is a high probability that all these practices may have negated the effect of geology on the K status of soils and especially on juice K concentration at the time of harvest. It was clear that seasonal differences and fertilisation affected the nutritional status of the vines more than geology. / AFRIKAANSE OPSOMMING: In Suid-Afrika is daar tans min wetenskaplike inligting oor die effek van verskillende geologiese moedermateriale op die prestasie van wingerd beskikbaar. Hierdie aspek is veral van belang in die Helderberg-area, waar moedermateriaal oor ‘n baie kort afstand van graniet na skalie kan wissel. Dit lei daartoe dat skalie-, sowel as granietgronde, dikwels binne dieselfde wingerd voorkom. Die doelwitte van die studie was om: (i) die voedingstatus en ander grondkundige eienskappe van die verskillende moedermateriale (skalie en graniet) en oorliggende gronde te kwantifiseer (ii) die impak van geologiese verskille in die grond op wingerd se voedingstatus en sekere wingerdkundige parameters, te ondersoek. Hierdie studie is oor twee seisoene (2006/2007 en 2007/2008) gedoen. Twee Sauvignon blanc en twee Cabernet Sauvignon wingerdblokke is geselekteer by twee verskillende lokaliteite vir elke kultivar in die Helderbergarea, Suid-Afrika. Beide skalie- en granietgrond is binne elke blok geïdentifiseer. Kaoliniet was die dominante mineraal, met kwarts en veldspaat sub-dominant, terwyl spore van mika ook in beide skalie- en granietgronde gevind is. Granietgronde het betekenisvol hoër hoeveelhede growwe sand bevat, terwyl skaliegronde meer fyn sand bevat het. Hierdie verskille het ‘n effek op waterhouvermoë gehad en daartoe gelei dat waterinhoude oor die algemeen hoër was vir skaliegronde. Skaliegronde het groter hoeveelhede totale K bevat, maar granietgronde se vermoë om K vry te stel was hoër, omdat hulle ‘n hoër konsentrasie oplosbare K bevat het. Die Q/I parameters, potensiële buffervermoë vir K (PBCK) en ewewig aktiwiteitsverhouding vir K (ARK), is nie op ‘n konsekwente wyse deur geologiese verskille beïnvloed nie. Vir die Sauvignon blanc wingerde was kalium konsentrasies in blaarskywe (gemonster voor oes in 2007) hoër vir graniet- as vir skaliegronde. Kalium konsentrasies in die sap vanaf Cabernet Sauvignon (gemonster in 2007) het hoër geneig vir granietgronde. In 2008 het die kalium konsentrasies, vir beide kultivars, hoër geneig in sap vanaf skaliegronde. Gedurende dié seisoen het die pH van sap ook hoër geneig vir Sauvignon blanc vanaf skaliegronde, wat dus ooreenstem met die K inhoud van die sap. Stikstof konsentrasies was hoër in sap vanaf skaliegronde vir Cabernet Sauvignon (2007) en vir Sauvignon blanc (2008). In terme van die wingerde se waterstatus, het stokke op die granietgrond, by een van die lokaliteite, geneig om gedurende beide seisoene onder groter stremming te wees op graniet as op skaliegrond. In hierdie Sauvignon blanc en Cabernet Sauvignon wingerde, is K voedingstatus nie op ‘n konsekwente wyse deur geologie geaffekteer nie, maar gedurende sommige seisoene was daar wel duidelike tendense vir ‘n spesifieke kultivar. Omdat die stokke binne dieselfde blok op skalie- en graniet gronde geplant is, was grondvoorbereiding eenders vir die twee grondtipes terwyl besproeiingskedule, lowerbestuur en klimaatstoestande ook identies was. Daar is dus ‘n hoë waarskynlikheid dat al hierdie faktore daartoe kon bygedra het dat die effek van geologie op die K status van van gronde versluier is, veral die effek op die K inhoud van sap teen oestyd. Dit was duidelik dat seisoenale klimaatsverskile en bemestingspraktyke ’n groter effek as geologie op die voedingstatus van die wingerd gehad het.