Properties and Classification of Soils of the Swedish Long-Term Fertility Experiments: IV. Sites at Ekebo and Fjärdingslöv
The Ekebo soil was classified as a coarse-loamy, mixed, mesic Oxyaquic Hapludoll according to the Soil Taxonomy and as a Haplic Phaeozem according to the World Reference Base for Soil Resources (WRB). The soil profile consisted of a very dark greyish brown Ap-horizon over a compact subsoil with porosity and permeability decreasing with depth. The textural composition of the Ekebo profile was almost uniform, with 19% clay, 36% silt (2-60 m) and 45% sand, on average, but an increasing content of stones and gravel up to 15% with depth. Amounts of carbon and nitrogen in the Ekebo soil were 90 t C ha-1 6.1 t N ha-1 in the Ap-horizon, respectively, and the subsoil to 1 m contained 34 t C ha-1 and 3.3 t N ha-1. The sum of cations amounted to 8.7 cmolc kg-1 soil in the Ap-horizon and 6.8 in the subsoil. The main clay minerals in the Ekebo soil were mixed-layer minerals showing concentrations of 25-39% throughout the profile, followed by illite, 19-31%. Vermiculite amounted to 2-7% and kaolinite to 2-5% while chlorite was only present in the topsoil. The Fjärdingslöv soil was also classified as a coarse-loamy, mixed, mesic Oxyaquic hapludoll according the Soil Taxonomy and as a Haplic Phaeozem according to WRB. The soil profile consisted of a thick very greyish brown A-horizon over a subsoil with calcium carbonate content (0.13-14.9%) increasing with depth. The soil texture was a sandy loam with 10-20% clay. The bulk density increased with depth from 1.60 to 1.87 kg dm-3. Carbon and nitrogen present in the Ap-horizon amounted to 61 t C ha-1 and 6.2 t N ha-1, and 30 t C ha-1 and 3.8 t N ha-1 were found in the subsoil. The cation-exchange capacity amounted to 12.1 cmolc kg-1 soil in the Ap-horizon and was somewhat lower in the subsoil. The clay mineralogy was as follows. The content of mixed-layer minerals was higher than that of illite in the top and upper subsoil. Vermiculite amounted to 6-10%, chlorite to 2% and kaolinite to about 1% in the profile. Although both soils ended up as Hapludolls in the classification, there are differences in productivity. Fjärdingslöv produces somewhat higher yields. Owing to the fact that several Swedish agricultural soils are classified as Mollisols but their character is more similar to Inceptisols, a revision of the required characteristics for a mollic epipedon is discussed.