Response of different crops to soil compaction—Short-term effects in Swedish field experiments

• The response of different crops to compaction were compared in totally 40 experiments.
• For barley and wheat, moderate compaction increased yield compared with no traffic.
• In general, dicots were more sensitive to compaction than monocots.

Soil compaction is generally regarded as negative for crop growth, although many studies show a curvilinear relationship between bulk density and crop yield. In the literature, there are few systematic studies of differences between crop species in their response to compaction. This study used results from short-term Swedish field experiments to analyse the sensitivity of different crops to compaction. The crops included were barley (Hordeum vulgare L.), horse bean (Vicia faba L.), oilseed rape (Brassica napus L.), oilseed turnip rape (Brassica rapa ssp. oleifera (DC.) Metzg.), oats (Avena sativa L.), peas (Pisum sativum L.), potato (Solanum tuberosum L.), rye (Secale cereale L.), sugar beet (Beta vulgaris L.), and wheat (Triticum aestivum L.).In total 39 experiments were analysed, in two series with spring-sown crops and one with autumn-sown crops, all on soils loosened by mouldboard ploughing. The experiments included different levels of tractor traffic applied track-by-track at the time of seedbed preparation, and a control treatment with no traffic. Bulk density was determined after traffic and expressed as degree of compactness (DC), which is the bulk density in percentage of a reference density.With moderate recompaction, wheat and barley showed a yield increase compared with untrafficked soil, while other crops showed little or no yield increase on average. Oats reacted more negatively to compaction than wheat and barley. Monocots generally had a higher optimum DC than dicots, but the differences were small. Yield losses at high DC values were greater for dicots, especially pea and horse bean crops, although for sugar beet and oilseed rape there was no clear difference compared with cereal crops.