Soil compaction and farm sustainability indicators

This paper outlines the bio-physical processes and consequences of soil compaction, its economic significance for farmers, and the possible reasons for mismanagement of soil. Methodologies for valuing the effects of soil degradation are surveyed. The goal of developing a sustainability index for on-farm monitoring, leads to a review of economic modelling of soil use in cropping. Considerable insight has been gained overseas by modelling of cropping, soil degradation, and farmer choices regarding management of soil. The impacts of soil compaction, and the slow rate of rejuvenation of soils in the Manawatu, are sufficiently well understood to conclude that increased inputs of manufactured capital, energy and fertilizer inputs cannot substitute for lost soil properties. But a lack of suitable data and an absence of precise knowledge about the relationships between cropping and soil degradation, and the rate at which other inputs can substitute for soil properties, means that farm level indices of sustainability are not feasible at present. The report concludes by proposing targets for future soil compaction research