soil depth

Many soil series do not have a deep, uniform soil profile. Restrictive subsurface layers often interfere with root penetration. In these soils, plant roots will be concentrated in the upper part of the soil profile. For example, in the Renshaw loam profile (Figure 4), the majority of the plant roots will be in the top 18 inches because the gravel below is a poor rooting environment. This type of information is important for irrigation management.

Soil Depth

Soil depth refers to the thickness of the soil materials that provide structural support, nutrients and water for plants. In North Dakota, soil series that have bedrock 10 to 20 inches below the surface are described as shallow. Bedrock from 20 to 40 inches is described as moderately deep.

Most soil series in North Dakota have bedrock at depths greater than 40 inches and are described as deep. Depth to contrasting textures is given in the soil series descriptions of the soil survey reports.

The depth to a contrasting soil layer of sand and gravel (Figure 4) can affect irrigation management decisions. If the depth to this layer is less than 3 feet, the rooting depth and available soil water for plants is decreased. Soils with less available water for plants require more frequent irrigations.

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