FERTILISER GUIDELINES FOR THE WINE INDUSTRY

Correct irrigation scheduling and maintenance of systems are essential to ensure correct fertilisation. Acidification under drippers is a real danger and should be monitored and managed. Failure to do so can impede root growth and uptake of nutrients from the wetted zone. Soil type (texture) needs to be taken into account when the size and timing of fertiliser applications are decided on. The use of water soluble fertilisers is complicated when the soil remains wet in spring/early summer, since irrigation is not required under these conditions. It is better to wait with the 1 st fertilisation application until the soil temperature starts to rise (>15 ᵒ C), and then applying it with a light irrigation. LIQUID FERTILISERS The most commonly used products are UAN and AN. The popularity of the products relative to water-soluble fertiliser has declined due to the fact that transport of these products are often difficult and expensive. The risks or prac tical implications of using these products through irrigation systems are similar to those of water soluble products. ENRICHED ORGANIC FERTILISERS Chicken manure and fertiliser are mixed together in varying ratios to form enriched organic fertilisers. There is a variety of formulations [12-3-3(18), 10-2-6(18), 9-2-9(20), etc.] and brand names for these products. The prod ucts usually have a lower nutrient concentration than pure fertilisers, and are available as a pelleted product (4 mm pellet) or as a powder mixture. Pelleted

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TABLE 22: Typical chemical composition of organic materials.

Resistance

Moisture N

Material

pH

Ohm

% %

Grape skins Cow manure

7.0 8.0 7.1 7.6

120

43 58 13 70

1.7 1.8 3.9 0.9

90 50 70

Chicken manure

Compost

80