NRCS to Implement New Soil Erosion Prediction Model

The USDA’s Natural Resources Conservation Service (NRCS) is implementing a new soil erosion prediction model, RUSLE2 (Revised Universal Soil Loss Equation 2), to be used by Iowa’s field offices for conservation planning beginning January 2004.

RUSLE2 is an advanced, user-friendly software model that predicts long-term, average annual erosion by water. It can be used for a broad range of cropland, hayland, pasture, construction, and forestry sites.

This new model is an improvement over its predecessors USLE, released in the early 1960’s, and RUSLE, which was released in the early 1990’s.

“The biggest change over previous erosion prediction models is the improved data that is incorporated into RUSLE2,” said Iowa NRCS State Agronomist Barb Stewart. “For example, previous models used climatic data from the 1930’s to the 1950’s. RUSLE2 uses climatic data from 1960 to 1990, a timeframe that saw more rainfall and more intense storms.”

Another change over previous erosion prediction models is the amount of credit that is given to long-term no-till. According to Stewart, a true long-term no till (no-till for at least seven consecutive years) will have greater soil loss reduction.

RUSLE2 is built on USLE and RUSLE fundamental structure, but computes average daily soil loss, which is summed to generate an average annual soil loss.

“The information used to develop RUSLE2 is the most recent available for climate, soil, topography and land use. This will produce more accurate soil loss estimates to guide conservation planning,” said Stewart.

Other changes and improvements include new county-specific climate data, new methods for handling residue, and perhaps the most obvious change, a new graphic user interface that makes RUSLE2 easier to read.

Stewart says the long-term impact of RUSLE2 will be an increase in erosion rates from what the RUSLE model indicated.

“We think the RUSLE2 numbers are more realistic to what is actually happening in the field,” she said. “RUSLE was giving too much credit to residue levels. A true no-till system will show significant reduction in soil loss, while any tillage will see a jump in erosion rate.”

The NRCS provides leadership in a partnership effort to help people conserve, maintain and improve our natural resources and environment. To find out more about Iowa NRCS, visit the website at www.ia.nrcs.usda.gov.

< Back to 2003 News Releases