Figure 3-19. Cracks
Large reversible trans-horizon cracks extend from the soil surface deep into the subsoil of this clayey soil, which is classified as a Vertisol.
Two kinds of trans-horizon cracks are recognized: reversible and irreversible. Subsurface-initiated reversible trans-horizon cracks form as a result of appreciable reduction in water content from field capacity in horizons or layers with considerable extensibility. They close in a period of days if the horizon is brought to the moderately moist or wetter state. They extend upward to the soil surface unless there is a relatively thick overlying horizon that is very weakly compacted (loose or very friable) and does not permit the propagation of cracks. These cracks greatly influence ponded infiltration rates, hydraulic conductivity, and evaporation.
Soil Survey Manual, Ag. Handbook 18, 2017, (p. 163).
Figure 3-19. Cracks
Large reversible trans-horizon cracks extend from the soil surface deep into the subsoil of this clayey soil, which is classified as a Vertisol.
Two kinds of trans-horizon cracks are recognized: reversible and irreversible. Subsurface-initiated reversible trans-horizon cracks form as a result of appreciable reduction in water content from field capacity in horizons or layers with considerable extensibility. They close in a period of days if the horizon is brought to the moderately moist or wetter state. They extend upward to the soil surface unless there is a relatively thick overlying horizon that is very weakly compacted (loose or very friable) and does not permit the propagation of cracks. These cracks greatly influence ponded infiltration rates, hydraulic conductivity, and evaporation.
Soil Survey Manual, Ag. Handbook 18, 2017, (p. 163).