Physical Properties

Soil Structure

Sand, silt and clay particles are the primary mineral building blocks of soil. Soil structure is the combination or arrangement of primary soil particles into aggregates. Using aggregate size, shape and distinctness as the basis for classes, types and grades, respectively, soil structure describes the manner in which soil particles are aggregated.

Aggregate Stability

Soil aggregates are groups of soil particles that bind to each other more strongly than to adjacent particles. Aggregate stability refers to the ability of soil aggregates to resist disintegration when disruptive forces associated with tillage and water or wind erosion are applied. Wet aggregate stability suggests how well a soil can resist raindrop impact and water erosion, while size distribution of dry aggregates can be used to predict resistance to abrasion and wind erosion.

Bulk Density

Bulk density is an indicator of soil compaction. It is calculated as the dry weight of soil divided by its volume. This volume includes the volume of soil particles and the volume of pores among soil particles. Bulk density is typically expressed in g/cm3.

Water Capacity

Available water capacity is the maximum amount of plant available water a soil can provide. It is an indicator of a soil’s ability to retain water and make it sufficiently available for plant use.

Infiltration

Infiltration is the downward entry of water into the soil. The velocity at which water enters the soil is infiltration rate. Infiltration rate is typically expressed in inches per hour. Water from rainfall or irrigation must first enter the soil for it to be of value.

Slaking

Slaking is the breakdown of large, air-dry soil aggregates (>2-5 mm) into smaller sized microaggregates (<0.25 mm) when they are suddenly immersed in water. Slaking occurs when aggregates are not strong enough to withstand internal stresses caused by rapid water uptake. Internal stresses result from differential swelling of clay particles, trapped and escaping air in soil pores, rapid release of heat during wetting, and the mechanical action of moving water.
A photo of several people standing in a field of cover crops that are about shoulder high.

Registration Open for 2026 Soil Health Schools!

The Coalition will host two Soil Health Schools in 2026! The West River Soil Health School is set for June 24-25 near Caputa, SD, and the South Dakota Soil Health School is set for Sept. 15-17 near Twin Brooks and Marvin, SD. These events are designed for agricultural producers as well as anyone with an interest in learning how to manage soils for resiliency and profit. The agenda features classroom style presentations by producers and technical experts from across the state and region, as well as hands-on experiences in the field. Area producers will share their challenges and successes with various methods for improving soil health, to an average class size of 30-40. Registration is open, so check out our events page to learn more!

News & Events

Awards Announced at Soil Health Conference

Awards Announced at Soil Health Conference

During the Tenth Annual Soil Health Conference, Jan. 13-14 in Aberdeen, SD, the South Dakota Soil Health Coalition announced the winners of its two annual awards as well as the winners of its student essay and video contests. Doug Sieck was named the 2026 Legacy Award...

Farmers growing profits and soil health with winter camelina

Farmers growing profits and soil health with winter camelina

By Stan Wise By now, most people working in agriculture have heard that growing a cover crop after a cash crop is harvested can make a big difference in soil health. Healthy soil pays off in a number of ways, including reduced input costs and increased operational...

Job Announcement: SDSHC Team Member

Job Announcement: SDSHC Team Member

About Us: The South Dakota Soil Health Coalition led by farmers and ranchers, supports the advancement of land stewardship and profitability by nurturing life from the soil up. Founded in 2015, SDSHC is a non-profit membership organization. The South Dakota Soil...