Predicting Soil Loss with RUSLE2

RUSLE2 is the simulation program helping you to determine how much soil is lost from your fields, how that compares to what is tolerable, and the impact of practices to reduce soil loss.

Calculating soil loss is part of the soil conservation planning process. Soil loss is determined using RUSLE2, the second version of the Revised Universal Soil Loss Equation. RUSLE2 estimates average annual sheet and rill erosion over the crop rotation in tons per acre per year based on crop management practices, tillage practices, soil properties, and rainfall. Soil loss estimated by RUSLE2 is an estimate and is used in the planning process to determine 1. if actual soil loss (A value) is less than tolerable soil loss value) (See: A Values and T Values: What is That All About?) and 2. how different combinations of soil conservation practices change soil loss.

RUSLE2 estimates soil loss using the equation: A = R x K x LS x C x P

1. R: The R Factor represents both the amount and intensity of rainfall. This factor varies across Pennsylvania and more than doubles between northwestern to southeastern Pennsylvania. A higher R factor reflects rainfall patterns that can lead to increased soil loss. Where you farm makes a difference when estimating soil loss.
2. K: The K or soil erodibility factor is related to soil texture and stoniness and reflects how naturally resistant soils are to soil loss. The K factor can vary by soil type. As soil type changes between fields and across the landscape of your farm, the K factor can also change. Your farms' soils and your farm's landscape make a difference in estimating soil loss.
3. LS: The LS or slope length factor is the slope length and steepness factor. It can be determined in the field and by using digital slope data such as LiDAR data. The LS factor determines where in a field soil may detach and where in a field soil may be deposited. Soil conservation professionals are specially trained to determine the LS factor in the field and by using available landscape data. These professionals should be consulted in determining the LS value.
4. C: The C or Crop Management Factor reflects how agronomic practices influence soil loss. The more soil cover practices provide the more these practices reduce soil loss. This factor considers crop residue management, tillage practices including no tillage, crop rotation, and planting cover crops.
5. P: The P or Practice Factor reflects how crop management practices influence soil loss. Practices that promote farming on the contour, or with the landscape, and that trap soil will reduce soil loss. Practices such as contour farming, strip-cropping, and contour buffer strips are considered in the P factor.

In the planning process, your soil conservation professional will work with you to evaluate how your soils, weather, and farming practices influence soil loss. Management options for reducing soil loss and meeting farm management goals can be discussed. To better understand how your farm's soils and management influence soil loss, start by reviewing your soil conservation plan, monitoring your fields for evidence of soil loss, and keeping soil loss in mind when making changes to cropping or tillage practices.

Reference

Myers, J. 2022. Soil loss prediction RUSLE – Based. [PowerPoint slides]. USDA-NRCS. Stormwater Workshop, Spring Mills, PA.