Field emergence of Calabrese and onion seedlings in response to compaction treatments on the soil surface or at seed depth

SummaryThe effects of combinations of soil compaction at seed depth with light or heavy surface compaction on seedling emergence were compared with uncompacted treatments, on nine sowing dates. Integral impedance was affected by surface compaction, rainfall and soil moisture content. Although data from individual sowing dates did not indicate a general relationship between emergence and integral impedance, there were significant negative correlations when the pooled data from all sowing dates were analysed separately for each seed-depth compaction treatment. Calabrese emergence was also related to soil temperature, and onion emergence to soil moisture at sowing. Within sowings the effect of soil compaction was generally detrimental to calabrese but was dependent on soil temperature, whereas only seed-depth compaction after sowing appreciably reduced onion emergence.