Agriculture Reference
In-Depth Information
(2009) summarized evidence for adverse effects on microbial activity and spe-
cies diversity in the rhizospheres of glyphosate-resistant crops, an effect that could
occur when under-vine weeds are regularly sprayed with glyphosate. Organisms
such as earthworms benefit from not having potentially toxic accumulations of
Cu in soil from regular applications of Bordeaux spray. New Zealand research sup-
ports the view that, with greater organic inputs from a cover crop and reduction
in herbicide use, the balance between predator and pest insects and disease in the
vineyard is improved. However, whether these soil changes in organic vineyards
specifically result in improved fruit quality and “capture the
terroir
,” compared
with well-managed conventional vineyards, is debatable.
With respect to point 3, as yet there are no rigorous comparisons of the C
balance between conventional and organic viticulture. Although some vineyards
in France, New Zealand, Chile, and California claim to be “C neutral,” this neu-
trality is achieved through C offsets, generally through paying for the planting
of trees (buying C credits). However, more rigorous auditing (through a full
life-cycle analysis) needs to be done on both the vineyard C balance and the net
effect of C sequestration in trees before claims of C neutrality can be justified. In
2009, the Australian Wine Carbon Calculator (AWCC) was introduced to assist
Australian wineries measure their C footprint, primarily through estimating their
GHG emissions (see
www.wfa.org.au
). The AWCC uses internationally agreed
C-accounting protocols, and its output is acceptable for reporting to Entwine
Australia, the wine industry's national environmental assurance program (see
later). However, the AWCC is a “work in progress,” and a number of generaliza-
tions and assumptions about activities and processes must be used to complete it.
For example, the impact of emissions from agricultural soils, manure application,
N leaching and runoff, crop residues is not covered by the calculator, so the emis-
sion estimate is indicative only. Nevertheless, adjustment of input data allows a
winegrower to do a sensitivity analysis of the business to see which changes in
vineyard and winery practices have the most effect on the C footprint.
Beware—Science before Dogma!
In Australia, the National Standard for Organic and Biodynamic Produce (2009,
p.50) states that an “organic or biodynamic farm must operate within a closed
input system to the maximum extent possible. External farming inputs must be
kept to a minimum and applied only on an 'as needs' basis.” Such production is
often claimed to be sustainable. However, no commercial organic vineyard is sus-
tainable in the long term if it is completely “closed,” because nutrients are exported
in the grape or wine products (and prunings if they are removed from site), and
some loss occurs through leaching and as gases (in the case of N). A nutrient such
as P gradually reverts to less and less soluble forms in the soil, gradually becoming
unavailable to the vines.
