What does the term 'grade' refer to in soil structure?

In soil structure, the term 'grade' specifically refers to the strength and firmness of the soil peds, which are the aggregates or clumps of soil particles. This aspect of soil structure is crucial because it influences how easily water and air can move through the soil, as well as the soil's biological activity and overall health.

The firmness of the peds can affect how soils support plant growth and withstand erosion. Stronger, well-formed peds can improve the soil's resistance to compaction and enhance its ability to retain water and nutrients. This characteristic is essential for agricultural practices and land management since it can impact crop yields and soil conservation efforts. Understanding the grade of soil peds helps soil evaluators assess the soil's physical properties and can guide decisions regarding land use and management practices.