Characterisation of four sites in Denmark for long-term experiments on crop rotations in organic farming

摘要: A field experiment is conducted which focuses on different aspects of crop rotations for cereal production in organic farming. Three factors are included the a factorial design: A) fraction grass-clover and pulses rotation (crop rotation), B) catch (with or without bi-cropped clover), C) manure animal applied as slurry). The at four locations (Jyndevad, Foulum, Flakkebjerg Holeby), representing soil types climate regions Denmark. There 64 experimental plots both Jyndevad 72 12 Holeby. In autumn 1996 samples were taken chemical physical characterisation. horizons described 16 profiles each plot. From these bulked 0-25, 25-50 cm, 50-75 cm 75-100 depth. Soil texture, acidity (pH), content total carbon, nitrogen, labile phosphorus, exchangeable potassium, magnesium, extractable copper cation exchange capacity (CEC) determined all subset plots. water retention curves 2 to 4 site. few supplementary measurements carried out spring 1999 determine ploughing layer penetration resistance. elevation slope areas Foulum Flakkebjerg. The coarse sandy characterised Orthic Haplohumod, has loam classified Typic Hapludult, Agrudalf, Holeby Oxyaquic Hapludalf. There no marked slopes other effects Holeby. varies about 3 m across site 8 Flakkebjerg. maximum 4-5° sites. The depth A-horizon between sites with average depths 32 Jyndevad, 44 45 35 upper horizon, influenced by tillage visibly larger humus content. largely caused very deep A-horizons parts area. These two also only sites, where there consistent increase clay increasing matter plough twice high compared causes CEC here equal that layers, despite differences pH was highest soils Holeby, but plant-available P lowest here, especially K quite low indicating potassium deficiency may become problem this soil. The plant available 0-60 57 mm 127 92 120 0-100 76 193 142 182 contents may, however, cause deeper rooting thus effective capacities water. The resistance indicated compacted 30 dry bulk density increased most markedly approached 1.8 g cm-3 layer. Both least places restrict root growth.