Vineyard Nutrition
Soil nutrient balance affects grape yields and wine quality.
Chris Cooper of the UK Vineyards Association will discuss:
- What are you aiming to achieve with your vineyard?
- Soil types and the effect on rootstock and training
- Nutrient usage by the vine/plants
- Typical deficiency symptoms
- Identifying and rectifying the problem
- New technologies
Attendees will learn how different soils can affect the growth of vines and therefore the importance of site and rootstock selection. Attendees will gain a working knowledge of macro and micro nutrients and how these effect vine growth and development, problems associated with limited or excess nutrients, plus a guide on how other factors impact on vine growth and berry development.
Key Messages
- Soil pH for vines should be in the range of 6-7.5. Grapes will tolerate pH 4.5-8.5 but grape yields and wine quality will be affected as pH influences nutrient availability to the plant. Wet climates give greater potential for producing acid soils so pH must be regularly monitored. Excessive rainfall also leaches soil cations.
- Potassium plays a big role in processes within the plant and the ratio of Ca:Mg:K and K:Mg is important in regulation of the cation balance which influences the absorption of macro nutrients by the plant. Clay soils tend to have higher cation exchange capacity than sandier soils.
- Soil Organic Matter content is the result of Physical, Chemical and Biological activity and normally ranges from 4-8% with higher levels associated with improved and more homogenous soil structure. The presence of grass alleys between vines will enhance soil OM content.
- Nitrogen should not be applied in vineyards as it causes excessive top growth increasing the canopy density and decreasing sunlight penetration leading to increased mildew growth. This will also decrease the nutrients transferred to the grape bunches.
- Nutrient application can be related to crop take off, for example 1.3-1.6 kg N can be replaced per tonne fruit harvested.
- Leaf analysis for NPK can be done on the leaf lamina or petiole (centre stem) at bloom time for N, P and K.
- For micronutrients or trace elements, there is a leaf analysis guide available, and a general foliar feed can be applied. Epsom salts spray can be applied for cases of Mg deficiency.
- Leaves are good indicators of signs of nutrient deficiency and leaf analysis should be undertaken on a leaf opposite the first buds at flowering. Visible signs of deficiencies present as follows:
N > yellowing of young and old leaves
Mg > green veins but yellowing of leaf between veins first seen on older leaves
K > crisp burnt edge to leaves
Fe > young leaves anaemic, can be prevalent on chalky soil
Mn > yellow leaves, rare in UK
Take home messages
- Balancing soil macro and micro nutrient values will promote optimum grape yields and improve wine quality.
- Soil sampling for macronutrients should be carried out every 3-5 years.
- Application of lime will be necessary to maintain pH in the ideal range 6-7.5.
Leaf analysis provides a good guide to micronutrient status.