Garden with Insight v1.0 Help: anion

An anion is a negatively charged ion. Of the macronutrients (nutrients most needed for plant growth), nitrogen, phosphorus and sulfur are normally found in the soil as anions (NO3-, H2PO4-, SO42-). Anions can be in solution or adsorbed to some organic compounds in soil organic matter. There is an anion exchange mechanism similar to cation exchange, but anions are more tightly held by the organic matter and anion exchange is typically fairly slow. Plants absorb most of the anions they need from the soil water solution. This is one reason leaching of nitrogen and phosphorus is so injurious to plants -- because the replenishment of anions to the soil solution (through anion exchange) is slow.

How it works:
N leaching, P leaching