WINETECH Technical Yearbook 2019

JOHAN DE JAGER & BENNIE DIEDERICKS: Vinpro, Paarl KEYWORDS: Leaf analyses, soil analyses, vineyard management. Is it worth the effort for producers to take regular soil and leaf samples, or does this only generate more data without adding real value? Soil and leaf samples both play a distinct role in the vineyard monitoring process. The way in which they also complement each other gives producers a better understanding of the complex plant- soil interactions. Soil analyses reflect the chemical balances that are present in the root zone and indicate the concentrations, inter alia, of elements that are available for THE ROLE OF LEAF AND SOIL ANALYSES IN VINEYARD MANAGEMENT (PART 1) MAY 2019

uptake by the plant roots, in other words plant accessible nutrients. Leaf analyses on the other hand are an indication of the ability of the plant roots to take up and utilise the available nutrients given a specific set of circumstances. A leaf sample is a direct measurement of the grapevine’s nutrient status at the specific moment when the sample is taken. A combination of these analyses is especially important to accurately identify problems, monitor and determine a nutritional programme for a vineyard. This series of three articles will present a

comprehensive look at sampling, timing of sampling and the procedure during sampling with a view to soil and leaf analyses. The series will also discuss three types of fertilisation/chemical recommendations: • Before a new vineyard is established and before the soil analysis is done, namely stock fertilisation. • During the lifespan of a productive vineyard, evaluation and adjustment of fertilisation programmes every third year, namely maintenance fertilisation.

• Problem cases where deficiencies are observed or when weak spots occur in a vineyard block. The objectives of soil analyses are: • To characterise the chemical properties of the soil in order to recommend cultivation practices and applications of fertiliser, lime and gypsum that will create an optimal root zone for the plant, as well as ensure optimal nutrient uptake.