FERTILISATION GUIDELINES FOR THE TABLE GRAPE INDUSTRY

requirement of each individual block. In order to ensure that fertilisers are applied in a responsible and sustainable manner, irrigation, soil type and ecology/climate should also be taken into consideration. IMPLEMENTATI ON OF FERTI LI SATI ON PROGRAMME For implementation of a fertilisation programme, four aspects should specifically be considered: Correct product: – product choice is based on the requirement of the plant-soil- system, the producer’s management practices and the nature of the production system. The products that are available to producers include the following: Granular fertilisers, water soluble fertilisers, liquid fertilisers, slow-release fertilisers, enriched organic fertilisers, manure, compost and foliar nutrients. The products may contain a single nutrient, e.g. N, P or K, or it may contain a combination of NPK or even trace elements. Different combinations of elements occur in these composite products, enabling producers to select products with the correct nutrient balances for his specific needs. The products to be used will depend on the quantity required for each element, as well as the fertilisation approach. Where P, K, Ca and Mg are applied to rectify deficiencies in the soil, the use of single element fertilisers will be more practical and cheaper. On the other hand, mixtures could be very useful where maintenance fertilisation with N and K is done on a regular basis, or where P may also be applied regularly. A good knowledge of the various products and their characteristics are therefore necessary in order to make the best choice and to prevent unnecessary complication of the programme. The different products are discussed in detail, later. Correct number of instalments: – the concentration of the nutrients in the die different fertilisers determines the size of the instalment. However, this must be correlated with soil type, irrigation system, and managerial practices of the producer and naturally the nutrient requirement of the grapevines. The annual uptake of the elemental nutrients is supplied in detail in Table 8 of Chapter 5, together with the comment that these requirements must not, in all cases, be the total amounts that should be applied annually. There are several aspects that must be considered in order to prevent that mistakes are made, namely: • Vigour classification – as defined in Table 11 of chapter 5 – must be the deciding factor for directing the levels of N fertilisation. • Regular soil analyses – this indicates the status of the chemical balances in the soil. Deficiencies and excesses are identified and can be addressed by the fertilisation programme. Problems with sub-optimal soil pH are also indicated and can be rectified. • Leaf analyses – it may be used as an additional aid for checking the nutrient status of the grapevines. • Soil texture – it determines the frequency and size of the fertilisation instalments.

82 | PRACTICAL GUIDELINES FOR IMPLEMENTATION OF THE FERTILISATION PROGRAMME