Agriculture Reference
In-Depth Information
Nguyen and Haynes (1995) found little difference in overall energy efficiency when they
compared mixed sheep and arable farms in New Zealand. But they noted that the conventional
farms relied more on legumes for N supply, and therefore were more energy efficient than
European equivalents. Smolik
et
al
. (1995) compared conventional, minimum tillage and
alternative (equivalent to organic) systems of growing soya, wheat and barley over seven years
in South Dakota, USA. Overall, the alternative system had the greatest energy efficiency. The
minimum tillage system had the lowest efficiency because reduced direct energy input, as
tractor fuel, was more than balanced by increased fertiliser and herbicide energy input.
Comparing rotations of different productions systems in Iran, Zarea
et
al
. (2000) found the
energy efficiency of organic farming to be 81% better compared to high-input conventional
farming. In a similar investigation in Poland, Kus and Stalenga (2000) calculated a 35% higher
energy efficiency of organic compared to conventional farming.
Overall, the literature review suggests that organic methods generally use less energy per
unit area and per unit of output, both for individual crops and livestock types, as well as on a
whole-farm basis. Again, however, the setting of system boundaries, methods of calculating
the energy values of inputs and methods of calculating energy use efficiencies vary substan-
tially between studies. Comparisons across studies are hardly possible - there is an urgent
need for a commonly agreed standard methodology (Shepherd
et
al
. 2003).
Conclusions
Is organic farming more enironmentally friendly?
The evidence presented in this chapter indicates that there is wide agreement that organic
farming comes closest to an environmentally friendly agriculture (Table 12.2). Particularly
pronounced is the significant level of pesticide pollution in conventional agriculture; in organic
farming, in contrast, there is only a very limited use of pesticides. The differences are likely to
hold whether assessed per area or per unit of food produced (Shepherd
et
al
. 2003). A second
major area where organic farming is more environmentally friendly is soil conservation. Soil
care is a guiding principle in organic agriculture. It is expressed in higher levels of soil organic
matter, the active promotion of soil biological activity, more balanced nutrient cycles and lower
soil erosion risks. A third main benefit is the expressed goal to enhance biodiversity: organic
farming depends upon intact ecological balances and favourable biological processes expressed
in ecological services like pollination or pest control by natural predators (Alföldi
et
al
. 2002).
Stolze
et
al
. (2000) and others conclude that organic farming creates more favourable condi-
tions at the species and ecosystems level of f loral and faunal diversity than conventional
farming systems.
Less affirmative, though not necessarily less favourable than for conventional systems, is
the evidence that has been presented in fields like pollution of water resources and the food
chain with pathogens (due to the more pronounced use of organic fertilisers and manure). The
same applies to the emission of N
2
O and CH
4
(because manure stores are seen as a major
source and because, on an output unit scale, the CH
4
emission potential tends to be higher in
organic farming).
Organic agriculture is not exempt from the trend of intensification. Therefore, Reiter and
Krug (2003) and others stress that the increasing economical pressures endanger the positive
aspects of organic farming. In order to maintain the view of nature conservation of valuable
grassland, for example, a very low intensity of production is necessary. But because of increas-
ing intensification, this is hard to realise (Hopkins and Hrabe 2001). The same economic
