FERTILISATION GUIDELINES FOR THE TABLE GRAPE INDUSTRY

CHAPTER 8

TABLE 32: Seasonal guideline amounts for N , P and K fertilisation of grapevine nurseries.

Element

N

P

K

Amount (kg ha –1 )

120

12

55

Ratio

10

1

4.6

Sources

LAN(28)

Single supers(10.5)

KCl(50)

This fertiliser can be applied in three or more instalments starting from about 4 weeks after bud break up to January to February. There are strong indications that soil selection and management practices are generally greater determinants than fertiliser when it comes to nursery success. Nursery practices are characterised by, i.e. intense soil cultivation actions, of which the use of the rotary harrow probably contributes most to the destruction of structure and organic material. Great emphasis is justifiably placed on the application of compost and especially chicken manure, but it appears to be ineffective for increasing or even maintaining the organic material content of the soil. In this regard, urgent attention needs to be given to effective cover crops during winter (before planting), but also during summer, after the grafted vines have been uprooted, coupled with minimum cultivation. It has also been found that the practice of utilising mixing delve ploughs to a depth of only 40 – 45 cm, leads to a concentration of organic material in the bottom zone of the prepared soil depth, with an accompanying concentration of roots and poor utilisation of the already limited soil volume. Deeper soil preparation with more efficient shifting delve ploughs, deserve urgent attention in order to ensure nursery success.

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