Highly Erodible Land

Indiana FOTG

Section II

General:

The Food Security Act of 1985 required that soil survey map units be separated into three categories on the basis of potential erodibility due to wind erosion and sheet and rill erosion. A Highly Erodible Soil Map Unit list designates the category assigned to each map unit. It has been determined that no map units are highly erodible because of only wind erosion in Indiana. The equation for determining potential erodibility from sheet and rill erosion is: A= RK(LS)

A is the amount of soil loss in tons per acre, R is the rainfall factor, K is the soil erodibility factor, and L and S are slope length and steepness factors, respectively, and T is the tolerable soil loss in tons per acre.

A map unit is designated highly erodible (class 1) if the value (A) obtained from the equation is equal to or greater than 8 when the minimum slope length and minimum slope percent are used.

A map unit is designated potentially highly erodible (class 2) if the values obtained from the equation is less than 8 when the minimum slope length and minimum slope percent are used but equal to or greater than 8 when the maximum slope length and maximum slope percent are used.

A map unit is designated not highly erodible (class 3) is the values obtained from the equation is less than 8 when the maximum slope length and maximum slope percent are used.

The minimum and maximum slope percent are obtained from the map unit name, i.e., Miami silt loam, 2 to 6 percent slopes. Two is the minimum value and 6 is the maximum value. The minimum and maximum slope lengths were determined by district conservationist, soil scientists and other local people.

The following table show soil map units and their placement in the Highly Erodible Land (HEL) Classification System. Also, the columns labeled compliance and CRP slope information length and percent show the slope length and slope percent used in some HEL calculations. These numbers represent dominate slope length and slope percent as determined by SCS personnel. The column labeled PHEL (Class 2) managed as allows the SCS line officer to indicate how the map units designated as class 2 will be managed. This decision is based on field observations. Additional information about HEL classification is in the National Food Security Act Manual.

Example

Field Office HEL Data Table

Any County, Indiana

Map Unit Name / Component Name / HEL Classification / Compliance / CRP Slope Information / PHEL (Class 2) Managed As
Length / Percent
BeB / Belmore / 2 / 200 / 4
BhA / Belmore / 3 / 250 / 1
BhB / Belmore / 2 / 200 / 4
BkA / Berrien / 3 / 300 / 1
BlA / Blount / 3 / 200 / 1