Keywords: Environment, Bioenergy, Good farming practice.
INTRODUCTION: In recent years there has been increasing debate on the environmental impact of farming methods. Very often, this debate is based on subjective judgements as is inevitable in a complex system. There is a need for a factual, objective basis for discussion to allow a useful comparison of different farming methods and a Swedish initiative in this direction is discussed in this paper.
Fossil energy demand as well as emissions of carbon dioxide, nitrogen oxides, ammonia, nitrate and phosphate have been calculated for three types of agricultural systems with identical total product output: "Normal intensity", "Reduced intensity", and "Zero fertiliser nitrogen". Systems with lower yields were found to require larger areas.
The approach is a form of life cycle analysis. Emissions from fertiliser factories, transports, tractors etc. as well as land areas have been taken into account. Care has been taken to use current data, reflecting the status of technology and agriculture of today. The agricultural data have a Swedish base but the methods used can be applied elsewhere.
With the higher intensities of farming management there is a free "area resource", for which two alternatives are considered: "natural forest" or bio-energy production. In other words. for a certain given area one choice is to have agriculture on it all with low yields, another is to farm part of it in such a way that the yields are higher and the rest can be forest or "nature".
If the results on energy use and emissions are expressed per hectare of cultivated area, the lower intensities appear to be more environmentally favourable. However, for most environmental considerations, the total effect of the agricultural production is a more relevant measure. Expressed in this way, the "normal" intensity is slightly more favourable than the "reduced" for all parameters studied. "Zero nitrogen" has an advantage only in energy and carbon dioxide, but gives higher emissions of nitrogen oxide, nitrate and phosphate.
When bio-energy production is included, the "normal" intensity is the most favourable for all parameters. Extensification has no positive environmental aspects at all, compared to "normal" intensity. It has to be emphasised that a condition for the study is both current efficient technology concerning production and environmental control as well as "Good agricultural practices".
G Bertilsson, Hydro Supra AB, Landskrona, Sweden.
27 pages, 15 tables, 13 references.