Plant Health and Yield

There are seventeen nutrients that, when applied to soil, play a major role in determining plant health and crop yield. In order for plants to absorb these nutrients, the nutrients must be dissolved. When nutrients are dissolved, they are in a form called "ions" and are electrically charged.

Typically, most soil is made up of clay and organic matter. Both  fractions carry a negative charge and, since, in soil chemistry, "opposites attract" and "likes repel", they attract cation (positive) elements and contribute to a high CEC.

Nutrients that have a positive electrical charge, in their plant available form, include potassium (K⁺), ammonium (NH₄⁺), magnesium ( Mg⁺⁺), calcium (Ca⁺⁺), zinc (Zn⁺), manganese (Mn⁺⁺), iron (Fe⁺⁺), copper (Cu⁺) and hydrogen (H⁺). While hydrogen is not classified as a nutrient, it directly affects soil pH and is therefore important.

Nutrients that have a negative electrical charge in their plant available form are called anions and include nitrate (NO₃^-), phosphate (H₂PO₄^- and HPO₄^--), sulfate (SO₄^-), borate (BO₃^-), and molybdate (MoO₄^--).

Phosphates are unique in that they are highly reactive and are not mobile in the soil. Most phosphates will combine with other elements or compounds in the soil, other than clay and organic matter. The resulting compounds are not soluble, and will precipitate out of soil solution. In this state, they are unavailable to plants, and form the phosphorus "reserve" in the soil.