In the vineyard Goldilocks grape nutrition
There’s no single formula for achieving the right balance. Observe and respond when you see deficiency symptoms.
By Gary Strachan G
etting it just right isn’t easy. For some vineyards, it may never happen. There are too
many variables affecting vine nutrition to derive a “one size fits all” solution. Look at the soils. The humus or
clay content of soil ties up water and minerals and releases them slowly over time. If you apply fertilizer to a vineyard, some of it will get to the plant – sometime. What about rootstocks? Studies
have found that rootstocks differ not only in the rate at which they gather minerals but also rootstocks have different uptake rates for different minerals. In addition, the common rootstocks used in British Columbia, such as SO4, 3309, 101-14 etc., have little information available about their effects on mineral uptake. You’re on your own. Observe and respond when you see deficiency symptoms. Watch for leaf symptoms and do regular petiole analyses until your vineyard begins to come into balance. A balanced vineyard will enable the crop to achieve full maturity within a normal season and will require little or no hedging and topping. How does irrigation affect mineral uptake? Obviously, water is the medium by which minerals are drawn from the soil into the plant, thus the level of available water affects uptake. Evapotranspiration provides the “pump” that draws water and nutrients into the plant. If there is adequate nitrate nitrogen
and water available, growth will be strong, but if either of these is limited, the growth rate and plant development will be handicapped.
British Columbia FRUIT GROWER • Summer 2013 29
The mineral required in the greatest amount is nitrogen. It is the most potent in limiting growth and affects fruit quality and wine quality more than any other mineral. The major factor in whether water
deficit or nitrogen deficit will have an immediate effect is the soil’s ability to hold water or nutrients in reserve. Again, this is determined by the humus or clay content of the soil. Soils with high humus or clay content are less responsive to water
Don't ignore yellow patterns on leaves. They are probably a mineral deficiency of some sort. Look it up.
and nutrient management than sandy soils. If the water-holding capacity is high enough, vigour control by deficit irrigation may not even be possible and the only way to get vine growth into balance may be to grow larger vines.
Another factor that affects water
and nutrient uptake, especially phosphorus, is symbiosis with mycorrhizae. In sandy soils a mycorrhizal infection may be difficult
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