Agriculture Reference
In-Depth Information
farming in Australia, soil available P has declined to levels where yields are being compro-
mised and the sustainability of the farming system is being questioned (Penfold 2000).
Pesticides
The term 'pesticide' covers a wide range of chemicals (e.g. fungicides, herbicides, insecticides,
acaricides, algicides, lumbricides, molluscicides, nematicides, rodenticides, plant growth regu-
lators). Pesticide use in organic farming is very restricted. Only a few pesticides are approved
for organic use (e.g. sulfur, copper, natural pyrethroids) and tend to be used only as a last
resort for minority or protected crops. Synthetic pesticides are completely banned (Shepherd
et
al
. 2003). In addition to the pollution of surface and groundwater, there is also a risk of air
and soil contamination.
Many reviews come to the same conclusion: because synthetic pesticides are not permitted
for use in organic agriculture, the risk of contaminations of air, soil and water in this respect is
avoided (Condron
et
al
. 2000, Stolze
et
al
. 2000, Hansen
et
al
. 2001, Stockdale
et
al
. 2001).
According to Unwin
et
al
. (1995), the spraying of pesticides permitted in organic farming is
connected with a comparatively negligible risk due to low volatility. The exposure of certified
biocides is measured at extremely low levels when compared to conventional systems in organic
permanent crops, these being more prone to pests and diseases (Kabourakis 1996). The appli-
cation of powdered and f fluid substances permitted by organic standards may cause a short-
time impairment of air quality (Stolze
et
al
. 2000).
The impact of pesticides on water quality in organic systems has rarely been studied (Stock-
dale
et
al
. 2001). Again, however, most of the water contamination comes from herbicides used
in conventional farming. There is some debate about the disposal of sheep dip and the relative
risks of pyrethroids versus organophosphates. Organic farmers only use the former and they
are potentially more damaging to aquatic habitats.
Pathogens
Pathogenic organisms from livestock can contaminate surface waters used for drinking,
bathing or irrigation. The application of organic manures to agricultural land is one route by
which pathogens may be introduced into the human food chain. There are only few data avail-
able on the relative risks of pathogen transfer from organic and conventional farming
systems.
Pathogen levels can decline during manure storage, particularly if solid manure is actively
composted to increase the temperature of the heap (Kudva
et
al
. 1998, Himathongkham
et
al
.
1999, Nicholson
et
al
. 2002). Thus, it might be concluded that biodynamic farming provides a
lesser risk because manures are more often composted. So far, there are no data to prove this,
but research is on-going (Shepherd
et
al
. 2003).
The overuse of antibiotics and pesticides in conventional farming, in horticulture and
especially intensive enterprises like poultry farming, has the potential to lead to drug resist-
ance of pathogens and consequently to the contamination of the environment and the food
supply (APHA 2002, Allersberger
et
al
. 2003). In organic farming, the use of regular synthetic
veterinary medicines is restricted and the use of antibiotics for preventive treatments prohib-
ited (Kijlstra
et
al
. 2003). Therefore, organic agriculture does not carry the same risk as con-
ventional agriculture.
Climate and air
Global climate change (greenhouse effect) is considered one of the most urgent environmental
problems. The gases carbon dioxide (CO
2
), nitrous oxide (N
2
O) and methane (CH
4
) mainly
