Agriculture Reference
In-Depth Information
who have set a goal of “20 by 2020,” that is, 20% of the country's vineyards under
certified organic management by the year 2020.
The Cornell Soil Health Assessment provides a more balanced assessment of
soil health (Gugino et al., 2009). The underlying concept is that soil health is an
integral expression of a soil's chemical, physical, and biological attributes, which
determine how well a soil provides various ecosystem functions, including nutri-
ent cycling, supporting biodiversity, storing and filtering water, and maintaining
resilience in the face of disturbance, both natural and anthropogenic. Although
originally developed for crop land in the northeast United States, the Cornell soil
health approach is readily adapted to viticulture, as explained by Schindelbeck
and van Es (2011), and which is currently being attempted in Australia (Oliver
et al., 2013; Riches et al., 2013).
A most important subtext of the Cornell approach is the recognition of
“inherent” and “dynamic” factors of soil health. Collectively, the inherent fac-
tors determine a soil's “sense of place,” being primarily the influence of geology
(the rocks), climate, organisms living on and in the soil, topography (the relief ),
and time. In the absence of human intervention, these factors can be considered
immutable during a human's life span, in contrast to the dynamic factors such as
organic matter, soil pH, nutrient availability, structure, and water supply, which
can be manipulated by human activities, often quite quickly. Thus to understand
“what makes a soil healthy,” we need to understand something about the advan-
tages and disadvantages conferred by a soil's sense of place and how these are mod-
ified by interaction with dynamic factors that are subject to human influence.
The remainder of this chapter provides an introduction to the inherent fac-
tors of soil health, which leads logically in chapter 2 to criteria for the selection
of vineyard sites and preparation of those sites for planting. In succeeding chap-
ters, the main dynamic factors and how they can be managed to best advantage
in a vineyard are discussed in more detail. The final chapter draws these various
threads together to answer the question “what is a healthy soil?” in the context of
the objectives of individual grape growers and winemakers.
Inherent Factors of Soil Health
Well before the current interest in soil health, a soil scientist named Hans Jenny
(1941) published a topic called
Factors of Soil Formation
in which he demonstrated
with many examples how the soil that formed in a particular place was a product
of the interaction of several soil forming factors. These factors are the same as those
identified as inherent factors in the language of soil health. Table 1.1 gives a sum-
mary of the soil forming factors, their components, and some consequences of their
action. To understand a little of the complexity of the interactions, we can follow
the steps in soil formation when a rock is exposed to weathering for the first time.
