Rangeland Soils Lecture Notes

These flashcards cover the key vocabulary and concepts related to soil profiles, structures, and classifications as discussed in the lecture notes.

Soil Profile

A vertical exposure of soil horizons that shows the sequence of layers formed in the soil.

Horizons

Layers in the soil profile, typically referred to as A, B, and C, with distinct characteristics.

Pedon

The smallest sampling unit of soil that displays the full range of properties characteristic of a particular soil.

Aggregates

Clusters of sand, silt, and clay particles formed by binding agents such as organic matter.

Humus

Actively decomposing organic material that contributes to soil fertility.

Single Grained Structure

A soil structure typical of sandy soils that allows for good drainage but has low nutrient retention.

Granular Structure

A soil structure characterized by small aggregates, providing high porosity and good microbial activity.

Platy Structure

A soil structure with horizontally stacked plates that restricts water movement and root penetration.

Prismatic Structure

A soil structure with vertical columns that allows some root growth along cracks.

Columnar Structure

A soil structure with dense vertical columns that limits infiltration and root penetration.

Massive Structure

A soil structure where soil has no visible aggregates and behaves as one large coherent mass.

Soil Infiltration Rate

The speed at which water enters the soil, influenced by soil texture and structure.

Oxisols

Highly weathered tropical soils that are low in natural fertility and rich in iron and aluminum oxides.

Ultisols

Strongly weathered, acidic soils with low natural fertility, commonly found in humid climates.

Aridisols

Soils that form in arid climates with weak leaching, characterized by low organic matter and often high salinity.

Mollisols

Fertile grassland soils with a thick, dark, organic-rich surface layer, ideal for agriculture.