Terroir 2004 banner
IVES 9 IVES Conference Series 9 Soil clay mineralogy and potassium buffer capacity as potential wine quality determining factors in Western Cape vineyards

Soil clay mineralogy and potassium buffer capacity as potential wine quality determining factors in Western Cape vineyards

Abstract

The potassium (K) supply characteristics and clay mineralogies of a population of Western Cape soils were investigated to determine their potential effects on vine K uptake and wine quality. The total K contents of granite-, shale- and sandstone-derived soils varied, averaging 33.7, 26.1 and 4.5 cmol(+)/kg, respectively. Corresponding M NH4Cl exchangeable soil K levels were: 0.172, 0.042 and 0.035 cmol/kg. Ability to fix applied K also varied, decreasing from 0.350 in the shale-, to 0.188 in the sandstone- to -0.177 cmol/kg in the granite-derived soils. Potential buffering capacity for K was pH / liming dependent, particularly in the shale soils. Potassium uptake by Italian rye grass correlated negatively with K fixation. The K contents of Italian rye grass grown on the sandstone, shale and granite soils were, respectively, 2.32, 2.12 and 5.56 dry mass %. These results were explicable in terms of soil mineralogy. The presence of kaolinite in the clay fraction, with mica and K-rich feldspar cores in the silt fraction enabled the granite soils to release primary K, but conferred little power to fix, or to buffer K against luxury uptake or loss through leaching. In contrast, the shale soil clay fractions consistently contained vermiculite and interstratified 2:1 minerals. These conferred marked pH / liming dependent K buffer capabilities. The shale soils also contained K in micas in the non-clay fractions. The sandstone soils varied in terms of both mineralogy and clay content. Sandstone soils, in which the sand fractions were quartzitic were unable to deliver primary K. Similarly, sandstone soils having low clay contents had severely limited K buffering capabilities. The observed differences in the abilities of sandstone-, shale- and granite-derived soils to supply and buffer K may be sufficient to affect grape vine performance and wine quality in Western Cape vineyards.

Download the PDF

DOI:

Publication date: January 12, 2022

Issue: Terroir 2004

Type: Article

Authors

J. Wooldridge

ARC Infruitec-Nietvoorbij, Private Bag X5026, 7599 Stellenbosch, South Africa

Contact the author

Keywords

Clay, buffer capacity, granite, mineral, potassium, sandstone, shale, soil, vineyard, wine

Tags

IVES Conference Series | Terroir 2004

Citation

Related articles…

Altered lignans accumulation in a somatic variant of Tempranillo with increased extractability of polyphenols during winemaking

Vegetative propagation of grapevines can generate spontaneous somatic variations, providing a valuable source for cultivar improvement. In this context, natural variation in the composition of phenolic compounds in grapevine berries and seeds stands as a pivotal factor in crafting wines with diverse oenological profiles from the same cultivar. To deepen on the understanding of the physiological and genetic mechanisms driving somatic variation in grape phenolics, here we characterized a somatic variant from Tempranillo Tinto, the clone VN21, that exhibits an intense reduced berry skin cuticle and increased extractability of phenolic compounds during wine fermentation.

Read More

Chemical and sensory evaluation of Bordeaux wines (Cabernet sauvignon and Merlot) and correlation with wine age

This study was carried out on 24 vintages of Cabernet sauvignon and on 7 vintages of Merlot produced by two different Bordeaux growing areas. Proanthocyanidin monomers and oligomers, and several parameters of the proanthocyanidin fraction were analytically assessed.

Read More

The use of viticultural and oenological performance of grapevines to identify terroirs: the example of Sauvignon blanc in Stellenbosch

Identification and characterisation of terroirs depends on knowledge of environmental parameters, functioning of the grapevine and characteristics of the final product. A network of plots of Sauvignon blanc was delimited in commercial vineyards in proximity to weather stations at 20 localities and their viticultural and oenological response was monitored for a period of seven years. These experimental plots were further characterised with respect to climate, soil and topography.

Read More

From vineyard to bottle. Rationalizing grape compositional drivers of the expression of “Amarone della Valpolicella” terroir

Valpolicella is a famous Italian wine-producing region. One of its main characteristic is the intensive use of grapes that are submitted to post-harvest withering. This is rather unique in the context of red wine, especially for the production of a dry red wine such as Amarone. Amarone wines produced in Valpolicella different geographic origin are anecdotally believed to be aromatically different, although there is no systematic study addressing the chemical bases of such diversity. Aroma is the product of a biochemical and technological series of steps, resulting from the contribution of different volatile molecules deriving from grapes, fermentations, and reactions linked to aging, as well as one of the most important features in the expression of the geographic identity and sensory uniqueness of a wine.

Read More

The current state and prospects for the development of viticulture and winemaking in Greece

Viticulture in Greece is the oldest, but in recent years there has been a reduction of areas intended for the production of wine products. The article contains data on viticulture in Greece. Over time, the land of Greek vineyards is fluctuating. There is a trend towards a decrease in areas in connection with the quota of products from the EU.

Read More