Environmental impacts of organic farming - Organic Agriculture: A Global Perspective - page 278

Several studies have been conducted on energy use in organic farming systems that differ
in methodology and in the boundaries of the systems being studied. Furthermore, there is no
clearly defined system of conventional farming, which ranges from high input intensive
systems to near-organic systems. Therefore, it is difficult to make meaningful comparisons.
This must be taken into account when drawing conclusions from studies that compare organic
and conventional systems (Refsgaard et al . 1998).
Intensity of energy use
Direct on-farm consumption of fossil energy (e.g. for fuel and oil) needs to be distinguished
from indirect energy consumption, which results from the production of synthetic fertilisers
and pesticides, the transport of imported feedstuffs and from investment goods such as agri-
cultural machinery (Stolze et al . 2000).
Inputs of direct energy per unit area in the long-term DOK trial in Switzerland were similar
across conventional, low input and organic systems (Alföldi et al . 1995). Since basic operations
such as ploughing, cultivation, sowing and harvesting are likely to be similar, reduced fuel
costs in organic systems due to the absence of most pesticide applications and lower harvesting
energy inputs because of lower yields, are more or less balanced by increased fuel use for
mechanical weed control.
Inputs of indirect energy tend to be substantially lower in organic systems. The major dif-
ference is the greater energy use in conventional systems to produce and transport fertiliser,
particularly N fertilisers (Alföldi et al . 1995, Cormack 2000, Stolze et al . 2000).
If both direct and indirect energy use are considered together, calculations of energy con-
sumption per hectare indicate that organic farms use less energy than conventional farms
(Haas and Köpke 1994, Kalk et al . 1996). Lampkin (1997) calculated that average energy con-
sumption on organic farms amounts to 64% of conventional farms. Zarea et al . (2000) in Iran
and Fließbach et al . (2001) in Switzerland determined that the energy consumption of organic
farms amount to 30% to 50% of conventional farms. For organic potatoes and apples, energy
consumption per output unit is higher relative to conventional production. This is the result of
a higher energy input for mechanical measures like weed control and the lower mineral N fer-
tiliser use in conventional production (Alföldi et al . 2002).
Barbera and La Mantia (1995) found lower energy consumption on organic farms for olive
and citrus production in Sicily (Italy), both with regard to energy consumption per hectare
and per output unit. A comparison of the energy use per hectare for organic and conventional
farming (e.g. in UK, USA, the Philippines) showed a 30% to 70% lower consumption per unit
of land for organic systems (Pretty and Ball 2001).
Efficiency of energy use
There are varying results on the energy efficiency of different farming systems. In many
organic systems, the yield of crop and animal products is less than in conventional systems
(Alföldi and Niggli 1994, Stockdale et al . 2001). However, the size of the differences will depend
on factors such as farm type, soil type, climate and the intensity of production (Shepherd et al .
2003). Furthermore, no standardised scheme for calculating energy use efficiency exists.
Shepherd et al . (2003) state that analysis should take account of overall farm energy balance
and also include activities that are not crop specific (e.g. handling and application of manures
and fertilisers, winter catch crops, use of fallows for weed control). However, apart from a few
studies based on long-term rotation experiments (Alföldi et al . 1995, Hülsbergen and Kalk
2001) these energy inputs have not been considered. Thus, comparing individual research
results in this context is only of limited value (Stolze et al . 2000).