Agriculture Reference
In-Depth Information
5
Nutrients for Healthy Vines and Good Wines
Soil Fertility and Productivity
5.1
The
fertility
of a soil refers to its nutrient supplying power. It is one of the most
important soil factors affecting vineyard productivity, which is measured in tonnes
of grapes per ha (or sometimes tons per acre). For viticulture, soil physical prop-
erties, notably structure, aeration, and drainage are also very important determi-
nants of productivity, as discussed in chapters 3, 6, and 7. Because vines are grown
in permanent rows, and there are many cultural operations, soil physical prob-
lems are often more difficult to ameliorate than problems of soil fertility.
Soil fertility is assessed either by observing the condition of vines growing on
a particular soil or by measuring the nutrient supplying power of the soil itself.
The assessment should include recommendations on how to correct any problems
identified. Thus, assessment of soil fertility can be made in two parts:
1.
Diagnosis of nutrient deficiencies or excesses
. The aim here is to identify
which nutrients are deficient or in excess and the degree of deficiency or
excess. An excess of a nutrient, which may create an imbalance with other
nutrients, often leads to a nutrient toxicity.
2.
Estimation of nutrient requirements
. The goal here is to estimate how much
of a limiting nutrient is required to achieve optimum growth or how to
remedy a toxicity problem. Nutrient amendments can be made with
fertilizers, manures, and composts, or by growing cover crops that include
legumes.
Diagnosis of Nutrient Deficiency
5.2
The Plant
Visual symptoms
are the signs that indicate a deficiency or excess of one or more
essential elements in a plant. In the case of grapevines, such symptoms include
5.2.1
109
