Keywords: soil compaction, soil tillage, nutrient uptake, carbon mineralisation, stratification.
In conventional tillage systems in Europe, soil compaction and tillage occurs in a repeated compaction – loosening cycle. Both compaction and tillage affect soil physical properties and plant growth, and thereby also plant nutrient uptake. Compaction may restrict root growth and thereby nutrient uptake, and through the effects on aeration all biological soil processes are affected. However, effects of compaction are not always negative – recompaction of loosened soil is often found to increase yield. While effects of topsoil compaction can be repaired by tillage, subsoil compaction is very persistent and a threat to long-term soil productivity.
Tillage also has large effects on yield, especially coupled to plant establishment. While reduced tillage often is expected to decrease mineralisation of organic matter, this was not found in Swedish long-term tillage experiments. Shallow tillage or no-tillage may however cause a strong stratification of plant nutrients in the topsoil, which could be detrimental for plant growth. In most cases, effects of compaction and tillage on the concentration of nutrients in the plants are relatively small. Thus, effects on nutrient use efficiency are primarily due to the effects on crop yield.
Johan Arvidsson, Ararso Etana and Veera Kainiemi, Dept. of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, 750 07 Uppsala, Sweden.
20 pages, 8 figures, 7 tables, 40 references.