Applying soil quality indicators in the context of life cycle assessment in a Finnish case study

Purpose

In this paper, we present a case study of soil quality assessments for Finnish arable crop production. The aim was to assess the applicability of three soil quality indicators by testing available assessment models and data in the context of a life cycle assessment (LCA). The indicators were erosion, soil organic matter (SOM) and compaction, which are crucial effects of soil cultivation in Finland, strongly affecting the cultivation fitness of soil especially in the long run.

Methods

In this case study, we assessed the effects of four Finnish arable crop rotations. The functional unit was 1 metric ton of cereal or turnip rape seed on the farm. The model used for assessing SOM was Yasso07, VIHMA for erosion and COMPSOIL for compaction. We used data from two conventional and two organic farms, collected from 4-year-long crop rotations that included turnip rape, cereals and green manure ley. Farm data were supplemented with geographic information and data from the literature.

Results and discussion

The data needed for the assessment of soil erosion and soil carbon decline was in the main readily available at farm level in the Finnish agricultural database, the Finnish Meteorological Institute, and from geographic information systems. However, more data would have been needed in the cultivation history of the field parcels for an accurate assessment of soil carbon decline. With regard to soil compaction, we had difficulties in finding suitable data especially on machinery use, which is not available in public data sources. Moreover, the reliability of the compaction model COMPSOIL was questioned, as its performance has not been validated in Finnish conditions.

Conclusions

The erosion and SOM models were found to be suitable for use in LCAs. However, the model for the assessment of compaction was considered too difficult to use. Furthermore, the compaction model results need to be validated with field measurements to be considered reliable in Finnish conditions. This study provides a starting point for developing soil quality assessment in Finnish agricultural production.