FERTILISATION GUIDELINES FOR THE TABLE GRAPE INDUSTRY

to transport it directly from the cellar to the weak spots or young vines. There is no advantage in firstly composting it or “aging” it in heaps. Composting is a natural process that will, in any event, take place in the vineyard. In this way additional handling costs are eliminated, furthermore composting is generally not effective on farm level. The composition of several organic materials is indicated in Table 30.

TABLE 30: Typical chemical composition of organic materials.

Extractable nutrients

N

C

P K Ca Mg Na Mn Cu Fe Zn B

Material

pH

Moisture

Resistance

% %

%

mg kg –1

Ohm g/kg Grape skins 7.0 120 43 1.7 0.2 0.7 1.4 0.2 797 72 0.6 106 89 8.2 25 Cattle manure 8.0 90 58 1.8 0.5 0.9 0.8 0.3 2 159 94 12.4 272 272 9.0 36 Chicken manure 7.1 50 13 3.9 0.9 2.2 0.8 0.5 5 021 312 13.4 453 453 26.5 37 Compost 7.6 70 70 0.9 0.2 0.6 1.3 0.2 1 158 209 0.8 92 91 7.1 18 MI CRO-FI NE LIME AND GYPSUM Micro-fine lime and gypsum are relatively new products and are available as pellets, powders and suspensions and the fineness varies from 5 – 50 microns. Because it is so fine, it can percolate in suspension with water, through the soil down to the root zone. The very small particle size implies that the reaction surface is much larger than that of standard lime and standard gypsum products, and chemical reactions in the soil may occur much quicker. For these reasons it must be used judiciously, especially lime that will affect the pH of the soil. The products have the following applications: • Supplementation of Ca in the root zone • Elimination of acidification below drippers and micro-sprinklers • Leaching of Sodium from the root zone The micro-fine products cannot replace lime and/or gypsum during soil preparation, or where lime or gypsum applications are required for rectification over the whole soil surface of the vineyard. Because the products are so fine, they are very reactive. Large shifts in Ca concentrations and/or pH may thus take place over a short period. Little research has been done on this aspect and it is therefore difficult to quantify. Because the reaction takes place quickly and completely, the slow releasing effect of the coarser product is lost. For long term crops the maintenance of favourable pH and Ca concentrations over time, it is very important.

90 | PRACTICAL GUIDELINES FOR IMPLEMENTATION OF THE FERTILISATION PROGRAMME