Mulder's chart is a circular diagram of the mineral nutrients, with lines connecting pairs that interact. One set of lines marks antagonism, where an excess of one element reduces another; another marks synergism, where one aids another. It is named after the Dutch agronomist D. Mulder, who compiled such interactions in the mid-twentieth centurybeing reviewed.
In practice
Growers use it as a checklist when a deficiency appears despite adequate feeding: if magnesium is low, check whether potassium, calcium or ammonium is high; if zinc is low, check phosphorus. It is a starting point rather than a law. Many interactions depend on concentration, pH, medium and crop, and some lines on popular versions are drawn from soil studies with little support in hydro or in cannabis specifically. Reviews such as Fageria and Rietra and colleagues give a more nuanced picture.
Don't confuse with
- Nutrient availability chart (pH chart): shows availability by pH, not element interactions.
- Feed chart: a dosing schedule.
Nutrient antagonism is when an excess of one element reduces the uptake or use of another, such as high potassium suppressing magnesium and calcium.A nutrient deficiency is a shortage of an essential element in the plant tissue, causing characteristic symptoms; the cause is often pH or uptake rather than an empty feed.Ammonium (NH4+) is the positively charged form of nitrogen; a small share stabilises root-zone pH, but too much reduces cannabis yield and quality.Zinc (Zn) is a micronutrient needed for auxin production and many enzymes; deficiency gives small, twisted new leaves and shortened internodes.pH measures how acidic or alkaline a solution is on a 0–14 scale; in growing it controls nutrient uptake, with soil best near 6.0–7.0 and hydro 5.5–6.5.A feed chart is a manufacturer's or grower's schedule of nutrient doses by week or stage; treat it as a ceiling to test against, not a rule.Nutrient toxicity is damage from an excess of an element in the plant, either directly or by blocking uptake of others; boron, manganese, copper and chloride are common culprits.Potassium (K) is a mobile macronutrient that controls water balance, stomata and enzyme activity; deficiency scorches the edges of older leaves.Phosphorus (P) is a mobile macronutrient used in energy transfer (ATP), DNA and cell membranes; cannabis needs moderate amounts and gains nothing from excess.
