Fertilisers and their application
The main movements of nutrients in a vineyard system are the removal by the crop, the recycling of organic material and the input of fertiliser. The amount of fertiliser required to be applied depends on vineyard age, cropping level, vine and soil nutrient status. The seasonal nutrient demand and uptake by grapevines infuences the timing of fertiliser application, typically fertiliser is applied during the main periods of root growth in the spring and autumn.
Fertilisers
There are a number of N, P and K fertilisers available which vary in concentration and solubility and often contain more than one macronutrient (Table 3). Fertiliser selection depends upon many factors (eg. effect on soil pH, speed of nutrient availability) and should include consideration of the irrigation system. An important feature of organic fertilisers is that nutrients must be broken down to inorganic forms (mineralisation) before becoming available to plants. There are several alternative fertilisers (eg. organic and bio-dynamic products) that claim to provide a range of nutritional benefts, but information for these fertilisers is limited for Australian soils. Organic fertilisers generally have a variable and often low content of macronutrients N, P and K (Table 4).
Table 3. Conventional NPK inorganic fertilisers and their nutrient content.
Regional issues
Grape growing regions differ in the issues that are important for grapevine nutrition. Soils vary from vineyard to vineyard and as the soil properties differ the importance of nutrient levels, water holding capacity, and soil pH will vary accordingly. Grape p
roduction in Australia can be separated into warm (irrigated) and cool (supplement irrigation) regions. Warm regions often have defciencies in Zn and Mo, while in comparison cool regions generally have defciencies in B.
Case Study
A grower leaves his canes in the vineyard after pruning and irrigation is managed to avoid excessive nutrient loss (run-off or leaching), the main loss of nutrient from this grower’s vineyard will be with the fruit harvested. A starting point for determining fertiliser application rates is therefore to estimate the total of nutrients contained in the fruit for a given yield (Table 5). For instance, a tonne of fruit removes about 2 kg N, a yield of 20 t/ ha would require a replacement of approximately 40 kg N/ha.
The calculations of the fertiliser requirement can be refned by conducting plant tissue analysis on petiole collected at fowering and compare it with the recommended ranges for nutrients in grapevine (Table 5).
Table 5. Nutrients removed per tonne of Chardonnay grapes and according to cropping yield level.
Conclusions and recommendations
Current best practice is to determine the soil nutrient status before the establishment of a vineyard and supply the necessary nutrients to avoid early poor vine growth. Subsequently, it is recommended to analyse petioles at fowering to determine vine nutrient levels. In addition, soil samples should be taken every 2-3 years to assess soil nutrient levels. Record keeping of petiole and soil sample results is important to recognise trends in nutrient levels. This information, together with visual observations of vine growth can greatly assist vineyard nutrient management. Fertiliser nutrient value and fertiliser type should be carefully checked to match the requirements of the vine.
The timing and amount of fertiliser applied should be undertaken in accordance with yield and grape quality targets, while note should be taken of irrigation and the weather conditions (particularly for foliar fertilisers).
Acknowledgments
The authors would like to thank the past and current staff of the National Wine and Grape Industry Centre (NWGIC) and all industry collaborators who contributed to this paper. Finally, unless otherwise acknowledged, the tables and fgures are results from recent and current funded projects at the NWGIC, and as such are in a preliminary form and have not yet been published.
AUTHORS:
Bruno Holzapfel, Leo Quirk, Ron Hutton and Jonathan Holland
