Evaluating Soil Health

Soil health is defined as the continued capacity of the soil to function as a vital living ecosystem that sustains plants, animals, and humans. Typically, soil health includes three types of soil characteristics: biological, physical, and chemical. Although sometimes used interchangeably, soil quality generally refers to soil chemical and physical properties. The main difference between soil quality and soil health is that the term soil health takes into account that soil is dynamic, like any other ecosystem. The organisms within the soil are just as important as what crops are growing above the soil. Soil organisms have the ability to improve soil structure, fight off plant disease, and make nutrients available to crops.

Evaluating Soil Health

Due to its dynamic nature, soil health measurements are used as a benchmark for future evaluation of the same soil system. It is important that soil is sampled at the same time of year under similar soil conditions (moisture status, temperature, etc). Some soil properties often used to evaluate soil physical properties are bulk density, infiltration, water holding capacity, and soil texture. Properties used to evaluate soil chemical properties typically include soil pH, plant available nutrients, soil nitrate, reactive carbon, soil organic matter, and electrical conductivity. Biological properties include the diversity and quantity of soil organisms (soil food web), total organic carbon, soil respiration, and soil enzymes. Some soil properties change over the course of decades or centuries, such as soil texture, while others change over the course of hours or days, such as soil nitrate.

Improving Soil Health

Many soil conservation practices improve soil health. Examples include no-tillage systems, incorporating cover crops, and manure usage. No-till systems improve soil structure, increase infiltration, and increase organic matter while cover crops and manure do the same plus increase soil microbe biodiversity and quantity.