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| Løes, Anne-Kristin; Øgaard, Anne Falk. |
| On five long-term organic dairy farms aiming at self-sufficiency with nutrients, soil concentrations of ammonium-acetate lactate extractable potassium (K-AL) and acid-soluble K was measured twice in topsoil (0-20 cm) and subsoil (20-40 cm) over periods of 6-14 years. Organic management had occurred for >9 years at the second sampling. On average there were most probably field level K-deficits. Even so, topsoil K-AL concentrations were medium high (65-155 mg K kg–1 soil), and did not decrease during the study period. However, for three farms, topsoil K-AL was approaching a minimum level determined by soil texture, where further decrease is slow. Subsoil K-AL concentrations were generally low (<65). The soils were mostly light-textured, and reserves of... |
| Tipo: Journal paper |
Palavras-chave: Nutrient turnover Farm nutrient management Recycling; Balancing and resource management. |
| Ano: 2003 |
URL: http://orgprints.org/5244/1/jas_010_(loesogaard).pdf |
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| Jensen, Lars Stoumann; Pedersen, Anders; Magid, Jakob; Nielsen, Niels Erik. |
| It is a well-known fact that catch crops have a significant effect on availability and loss of soil inorganic nitrogen (Thorup-Kristensen et al., 2003) and recently marked effects on soil inorganic sulphur dynamics have also been shown (Eriksen and Thorup-Kristensen 2002; Eriksen et al., 2004). However, we know much less about the effect of catch crops on phosphorous (P) and potassium (K) mobilisation and availability for the next crop. After several years of organic cash crop production, e.g. vegetables and cereals, yield levels may gradually be limited by soil P and K availability, depending on the initial status at conversion to organic production principles. This is particularly the case during the establishment phase of certain vegetable cultures... |
| Tipo: Journal paper |
Palavras-chave: Nutrient turnover Farm nutrient management Recycling; Balancing and resource management Air and water emissions. |
| Ano: 2005 |
URL: http://orgprints.org/6165/1/6165.pdf |
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