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.

West River Soil Health School Registration Open!

In 2024, the South Dakota Soil Health Coalition will host an additional Soil Health School in west of the Missouri River! The 2024 West River Soil Health School with be held June 26-27 near Caputa, SD! This school will focus on issues specific to the land, climate, and ag production systems of wester South Dakota. Class size is limited, so early registration is strongly encouraged!

News & Events

Coalition plans additional Soil Health School for West River

Coalition plans additional Soil Health School for West River

By Stan Wise PIERRE, SD – Since 2016, the South Dakota Soil Health Coalition has held an annual Soil Health School to offer an intensive educational experience that combines classroom instruction with hands-on field exercises. However, those schools have been held...

Grazing livestock on cropland pays off

Grazing livestock on cropland pays off

By Stan Wise PIERRE, SD – The core idea behind the regenerative agriculture movement is a simple one: Mimic nature. What did farmland look like before it was farmed, and how can producers make their operations look more like that picture? This concept lies at the...

Farmer reaps higher yields by interseeding soybeans

Farmer reaps higher yields by interseeding soybeans

By Stan Wise Alex Frasier has spent a lot of time studying what it takes to grow a successful crop. After studying ag production and precision technology at Lake Area Technical College, he has worked in ag retail and currently works as an agronomist in Aberdeen, SD....