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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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| Løes, Anne-Kristin; Øgaard, Anne Falk. |
| Agricultural soil on 12 farms converting to organic farming was sampled in 1989 and 1995 at the same sample points. Concentrations of plant-available (-AL) P, K, Ca and Mg, HNO3-soluble K, tot- N, tot-C and pH were measured in two layers. The average K-AL concentration and pH were reduced in both layers. The average P-AL concentration was reduced in the topsoil. K-AL and P-AL increased in samples with low concentrations and decreased in samples with high and very high concentrations in 1989. The total N concentration increased in the subsoil. Tot-N and tot-C increased in top- and subsoil with a low organic matter content. The net import of P, calculated by farm level nutrient balances, was negatively correlated to the change in kg P-AL per hectare in the... |
| Tipo: Journal paper |
Palavras-chave: Nutrient turnover; Farm nutrient management. |
| Ano: 1997 |
URL: http://orgprints.org/5945/1/Acta_1997%2C_Changes_in_the_nutrient_content...pdf |
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