Chapter 6 Revised Universal Soil Loss Equation (RUSLE)

1
Chapter 6Revised Universal Soil Loss
Equation(RUSLE)
2
Why is for soil loss important to nutrient
management planning?

• Water Quality concerns from sediment / turbidity
  and nutrients attached to particles
• Input parameter for the P-Index

3
Some things to know about the RUSLE Equation

• Results intended for planning purposes not for
  absolute prediction of soil loss
• Averaged over time and space in units of
  tons/Acre/year
• Developed from thousands of research plots over
  many years
• It is an index approach, not a strict model of
  the physics behind soil erosion
• It is not intuitive, but is relatively easy to
  use since many factors are in tables.

4
Some things to know about the RUSLE Equation
(Cont.)

• It is an index approach, not a strict model of
  the physics behind soil erosion
• It is not intuitive, but is relatively easy to
  use since many factors are in tables.

5
The RUSLE Equation

• A RKLSCP
• A Estimated Soil Loss
• R Rainfall-runoff erosivity factor
• K soil erodibility factor
• L slope length
• S slope steepness
• C cover management factor
• P Support Practice Factor

Used in Combination as LS
6
Rainfall-runoff erosivity factor (R)

• Values averaged over time and geographical area
• Tabulated by County (Table 6-1)
• What is the R Factor for Crawford County ?
• What is the R Factor for your District or County?

7
Soil Erodibility Factor (K)

• Soil Dependent, i.e. each soil mapping unit has
  a unique K Factor.
• Value is found in the Physical and Chemical
  Properties of the County Soil Survey
• In Northern 1/3 tier of State, K must be adjusted
  for freezing
• Adjusted K K0.83 rounded to nearest class in
  Table 6-2

8
LS Factor

• Describes topography influence
• For a given length, determine slope
• Field Method
• Soil Survey Method
• Use Average of Slope Class
• Use average slope length
• Use Table 6-3 to look up LS

9
Crop Management Factor (C)

• Describes influence of cropping practices
• In an individual pasture, estimate
• Type of cover Forage or Weed
• ground cover of dominant cover type
• If weeds Are taller than forage, estimate
  canopy cover of taller weeds and height
• Use Table 6-4

10
Conservation Management Factor (P)

• Describes influence of conservation support
  practices
• For a given County, determine the storm energy
  and intensity value (EI) from Table 6-1
• Determine Soil Hydrologic group from the Soil and
  Water Features Table of the County Soil Survey
• USE S factor from previous determination
• USE Tables on pages 6-6 6-7 to look up P

11
The RUSLE Equation

• A RKLSCP

Plug in values of factors and multiply to
determine A
12
Questions?