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Research article2004Peer reviewedOpen access

Terrestrial plants require nutrients in similar proportions

Knecht MR, Goransson A


Theoretical considerations based on nutrition experiments suggest that nutrient ratios of terrestrial plants are similar to the Redfield ratio found in marine phytoplankton. Laboratory experiments have shown that seedlings of many different plant species have similar nutrient concentration ratios when supplied with nutrients at free access. However, at free access, nutrients are likely to be taken up in amounts in excess of a plant's requirements for growth. In further experiments, therefore, the supply rate of each nutrient was reduced so that excessive uptake did not occur. Again, similar nutrient ratios were found among the plant species tested, although the ratios differed from those found in plants given free access to nutrients. Based on the law of the minimum, we suggest that optimum nutrient ratios be defined as the ratios found in plants when all nutrients are limiting growth simultaneously. The literature on nutrient concentrations was surveyed to investigate nutrient ratios in terrestrial ecosystems. Nutrients taken into consideration were nitrogen, phosphorus, potassium, calcium and magnesium. Based on the assumption that nitrogen is either the limiting nutrient or, when not limiting, is taken up only in small excess amounts, we calculated nutrient ratios from published data. The calculated ratios corresponded closely to the ratios determined in laboratory and field experiments


ecosystems; free access nutrition; law of the minimum; nutrinet ratios; plants

Published in

Tree Physiology
2004, Volume: 24, number: 4, pages: 447-460

      SLU Authors

    • Billberger, Magnus

      • Department of Ecology and Environmental Research, Swedish University of Agricultural Sciences

    UKÄ Subject classification

    Agricultural Science
    Forest Science
    Environmental Sciences related to Agriculture and Land-use

    Publication identifier


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