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POLICIES COVERING THE USE OF RUSLE2 IN DEVELOPING, REVISING, OR REVIEWING CNMPs

Starting on May 1st, 2003 all CNMPs developed in NYS will use RUSLE2 (Revised Universal Soil Loss Equation, Release 2) technology on all cropland covered by the CNMP. This includes all cropland covered by plans previously developed for highly erodible land (HEL) for Food Security Act (FSA) purposes, and non-highly erodible land (NHEL) cropland.

All cropland covered by the CNMP will have planned a total soil loss from sheet and rill erosion of less than or equal to the Tolerable Soil Loss (T) using RUSLE2. (ephemeral and permanent gully erosion caused by concentrated flow of water must also be evaluated and appropriately treated in the CNMP) “T” is the tolerable soil loss for the predominant soil type present in the field being planned. For CNMP purposes Review Teams will accept crop fields planned to no greater than 1 Ton over “T”. This does not imply general planning to T+1. Rather it provides reasonable flexibility for complex areas or fields.

CNMPs already underway, or previously signed and agreed to, that contains FSA HEL fields not planned to “T” are valid until the next annual CNMP review between the planner and farm management. At that time, these fields and any others not planned to “T” will be revised using RUSLE2.

CNMP that was already in the stage of development prior to May 1st, 2003 could be completed using RUSLE 1.05 or could be finished by using RUSLE2. After that point, any changes made to the rotations or tillage operations in an existing CNMP will be reevaluated using RUSLE2. Alternatives will be developed to meet the Tolerable Soil Loss (T) using the RUSLE2 technology.

The criteria for determining slope steepness and slope length for the use of the RUSLE2 equation in CNMPs will be as follows:

  1. Determine and record the slope percentage and slope length that are representative of predominant field conditions. Record the location of the slope measurement. Using a weighted average of slopes found throughout the field is acceptable, but keep records of the individual slopes measured.
  1. If compound slopes are present, determine the slope and slope length for each segment and enter this data into the RUSLE2 Slope Topography table.
  1. Steep areas not representative of a particular crop field may need to be treated as a separate planning unit, especially if a waterbody or conveyance to a waterbody is directly impacted.

Calculate and record the existing soil loss (benchmark condition) in the CNMP.

All plans submitted for review will contain documentation of RUSLE2 calculations.

Fields with similar slope topography/soils and crop rotations may be grouped to avoid time consuming data entry. There may be some fields where, in the professional judgement of the planner, the existing soil loss is obviously at or below “T”. In those cases, + where the plan is not submitted for a review, the Rusle2 calculations are not required. However, should that plan be chosen for a quality assurance review, the planner may be required to produce the calculations.

When a soil loss figure is required for a field as part of the NYS Phosphorus index and that particular field had no actual soil loss calculation made, the “T” value should be used. Use of the “T” value may not be favorable to the farmer/operator since the actual calculated soil loss prediction could be lower than “T”. In this case, Rusle2 calculation is recommended to produce an accurate input for the NYS Phosphorus index.