What percentage of organic matter classifies a soil as organic?

A soil is classified as organic when it contains a significant percentage of organic matter, which is typically defined as having 20% or more of its mass made up of organic material. This is crucial because organic matter plays a vital role in improving soil structure, water retention, nutrient availability, and overall soil health. Soils that reach or exceed this threshold are considered organic because they have a substantial component of decomposed plant and animal material, contributing to biodiversity and soil fertility.

In relation to the provided percentages, while options suggesting lower amounts of organic matter may indicate healthier soils compared to mineral soils, they do not meet the threshold required for classification as organic. Therefore, the correct percentage indicating organic soil is established at 20%, making the choice reflecting a higher threshold as misleading in the context of standard classifications.