Sufficiency ranges for lemon balm and nutrient removals in aboveground phytomass

A set of fertilizer experiments were conducted during three growing seasons with the aim of establishing sufficiency ranges and crop nutrient removals for Melissa officinalis L. Critical nutrient concentrations were determined by the Cate-Nelson method or by removing 10% of extreme high and low values, respectively if a positive response to a given nutrient was recorded or not. Sufficiency ranges for macro, micronutrients, and SPAD-readings were set as: 27.0-40.0g N kg(-1); 0.8-2.7g P kg(-1) (May-August); 1.5-3.8g P kg(-1) (September-November); 10.0-25.0g K kg(-1) (May-August); 18.0-32.0g K kg(-1) (September-November); 5.0-25.0g Ca kg(-1); 3.5-8.5g Mg kg(-1); 18-125mg B kg(-1); 5-25mg Cu kg(-1); 75-500mg Fe kg(-1); 20-300mg Zn kg(-1); 30-250g Mn kg(-1); 30-45 SPAD-units. These results will allow laboratories to use plant analysis as an important tool in improving the fertilizer recommendations for this species.