WINETECH Technical Yearbook 2019

THE ROLE OF SOIL AND LEAF ANALYSES IN VINEYARD MANAGEMENT (PART 2)

JOHAN DE JAGER & BENNIE DIEDERICKS: Vinpro, Paarl KEYWORDS: Leaf analyses, soil analyses, vineyard management. JUNE 2019

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? This series of three articles presents an in-depth discussion of sampling, timing of sampling and the correct procedure during sampling for soil and leaf analyses. Furthermore three kinds of fertilisation/ nutritional recommendations are considered, namely: • Stock fertilisation: Before establishing a new vineyard and before doing any soil preparation. • Maintenance fertilisation: Fertilisation programme every three years during the lifespan of a productive vineyard; programme is evaluated throughout to make adjustments. • Problem cases: Where deficiencies are observed or weak/low yielding spots occur in the vineyard block.

In this article, the second in the series, the focus is on soil analyses that provide a scientific basis for: • Adjustments in respect of soil preparation. • Compiling and monitoring balanced nutritional programmes. Soil analyses for grapevine establishment are used to characterise the chemical status of the soil; in other words to determine how suitable the environment is for grapevine roots and to quantify imbalances in nutrient concentrations. It is therefore used for chemical adjustments during soil preparation and also serves as a departure point for

it may take time before the results are received. • Mo n i t o r t h e s o i l p r e p a r a t i o n (Photos 4 and 5) and chemical adjustments in order to ensure that it has been done correctly; this is done by taking samples using profile pits after completion of soil preparation. This is the final opportunity to make adjustments (physical and chemical) before the new grapevines are planted in the deeper soil layers. • For the purposes of ma intenance fer t i l i sat i on i n produc i ng /bear i ng vineyards, soil samples should be taken every three to four years. • The soil samples can be taken at any time of the year. This should fit into the work programme, preferably when the soil is not too hard and the weather is not too MAINTENANCE FERTILISATION/ FERTILISATION PROGRAMME

fertilisation programmes. TIMING OF SAMPLING

• Sampling should be done timeously, be fo re so i l p repa rat i on , so t hat there i s suf f i c i ent t ime to make recommendat i ons ; t he ana l y t i ca l laboratories are sometimes busy and

PHOTO 1. Example of sampling through different layers of soil profile.