Plant+Nutrients

Here's one website on plant nutrients: []
 * Plant Nutrition** is the study of the [|chemical elements] that are necessary for growth. In 1972, E. Epstein defined 2 criteria for an element to be essential for plant growth:


 * 1) in its absence the plant is unable to complete a normal life cycle or
 * 2) that the element is part of some essential plant constituent or metabolite,

this is all in accordance with [|Liebig's law of the minimum]There are 17 essential plant nutrients. Carbon and oxygen are absorbed from the air, while other nutrients including water are obtained from the soil. Plants must obtain the following mineral nutrients from the growing media:


 * the primary macronutrients: nitrogen (N), phosphorus (P), potassium (K)
 * the three secondary macronutrients such as calcium (Ca), sulphur (S), magnesium (Mg).
 * the macronutrient Silicon (Si)
 * and micronutrients or trace minerals: boron (B), chlorine (Cl), manganese (Mn), iron (Fe), zinc (Zn), copper (Cu), [|molybdenum] (Mo), nickel (Ni), selenium (Se), and sodium (Na).