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Concentrations of soil potassium after long-term organic dairy production

Løes, Anne-Kristin and Øgaard, Anne Falk (2003) Concentrations of soil potassium after long-term organic dairy production. International Journal of Agricultural Sustainability, 1 (1), pp. 14-29.

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Summary

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 K-releasing soil minerals (illite) were low, never exceeding 6% of the mineral particles <2 mm diameter. Topsoil acid-soluble K concentrations were low (<300 mg K kg–1 soil) on two farms, medium (300–800) on three farms and decreased significantly on one farm. Cation-exchange capacity increased on two farms. This may indicate increased amount of expanded clay minerals caused by K-depletion. On self-sufficient organic dairy farms, purchased nutrients will be required by low soil nutrient reserves to avoid seriously decreased yields and quality of crops.


EPrint Type:Journal paper
Keywords:cation exchange capacity; clay minerals; nutrient balance; phosphorus; potassium; soil fertility; X-ray diffractometry
Subjects: Soil > Nutrient turnover
Farming Systems > Farm nutrient management
Food systems > Recycling, balancing and resource management
Research affiliation: Norway > NORSØK - Norwegian Centre for Ecological Agriculture
Norway > UMB - Norwegian University of Life Sciences
Deposited By: Løes, Anne-Kristin
ID Code:5244
Deposited On:07 Sep 2005
Last Modified:12 Apr 2010 07:31
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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