Agriculture Reference
In-Depth Information
can be achieved, preferably through winter rainfall (see “Leaching, Salinity, and
Sodicity Control,” chapter 4).
When prolonged drought occurs and water allocations for irrigation are much
reduced (as occurred during the “millennial drought” in Australia), vines may
receive only 30 to 40% of the optimum irrigation volume for one or more seasons.
This is an example of sustained deficit irrigation, which may maintain fruit quality
but will inevitably decrease yield and can adversely affect the long-term sustain-
ability of a vineyard.
Organic, Biodynamic, and Conventional Viticulture
Choices to be Made
Chapter 3 introduces the basic concepts and practices of organic and biodynamic
(BD) viticulture. The term “conventional viticulture” covers systems in which
synthetic chemicals may be used as fertilizers, as soil ameliorants, or for pest and
disease control. Vineyards where both organic and conventional practices are used
(ideally adopting the best of both) are sometimes called “integrated” systems.
In the following discussion, organic and BD systems are considered under the
generic term “organic,” provided that a BD system has C inputs comparable to
an organic system. This point was emphasized in “Cultural Practices for Organic
Viticulture,” chapter 3.
There are at least three main reasons for winegrowers to turn to organic
viticulture:
1. Many wine writers and an increasing number of winegrowers claim that
organic wines taste better and “capture the
terroir
” of a site.
2. Organic viticulture benefits the soil because the inputs of organic
materials and absence of chemical sprays promote a healthy soil biota,
which in turn enhances vine growth and fruit quality.
3. Organic viticulture is good for the environment. Losses of nutrients by
leaching are minimized, and C is conserved in the soil. Greenhouse gas
(GHG) emissions are indirectly reduced because chemicals and fertilizers
that are made using fossil fuel energy are avoided.
Point 1 is a subjective opinion and difficult to separate from the marketing
aspect of wine production. If consumers believe organic wines taste better, that is
their choice. In his review of conventional, organic, and BD viticulture, Johnston
(2013) concluded that insufficient scientific research has been conducted to test
the claims made for the superior quality and taste of organic and BD wines and
that much of what we hear is anecdotal. However, from limited studies so far in
Germany, Austria, and Italy (cited by Johnston, 2013), no consistent differences
have been found in juice composition or the sensory analysis of organic versus
