National Agricultural Pesticide Risk Analysis (NAPRA) provides an automated pesticide risk screening process by using an environmental fate model GLEAMS (Groundwater Loading Effects of Agricultural Management System). Results from the NAPRA include climate-based probabilities of off-site pesticide loadings and concentrations. NAPRA evaluation is limited to the bottom-of-the-rootzone and the edge-of-the-field. Implementing NAPRA requires interdisciplinary technical support and a variety of data inputs. We are working on this project with several agencies including USDA Natural Resources Conservation Service (NRCS), National Water and Climate Center (WCC) and Purdue University. The objective of this project is to implement the NAPRA process in Michigan to help identify best management practices to reduce hazadous off-site pesticide losses.

Databases are used in NAPRA:

1. Soils database

• The NRCS State Soil Survey Database (SSSD)
• Soil groups
• K value of soil
• Horizon depths
• Content of sand (%)
• Content of silt (%)
• Content of clay (%)
• Soil water retention values
• Depth of soil layers (in)
• Porosity (in³/in³)
• Field capacity (in/in)
• Wilting point (in/in)
• Saturated conductivity (in/hour)

2. Regional database

• Generated climate data by CLIGEN (Climate Generator)
• Location of the weather station
• Monthly maximum and minimum air temperature, solar radiation, dew point, and wind speed
• Measured climate data
• Total daily rainfall (in)
• Daily average air temperature (F)
• Mean monthly maximum and minimum air temperature (F)
• Mean monthly solar radiation
• Regional constants
• Effective hydrologic depth (in)
• Field drainage area (acre)
• Fraction of plant available water
• Specific surface area of clay (m²/g)
• Coefficient of pesticide uptake
• Organic matter

3. Pesticide database

• Active ingredient data
• Half-life (days)
• Pesticide available for washoff (%)
• Active ingredient data by the soil pH
• Application data (codes, methods, and timing)
• Application methods
• Application timing
• Chemical use practice
• Loss types

4. Crop/Tillage database

• Crop practices
• Dates of planting, trunction, maturity
• Root depth
• TR55 RCN crop category
• Leaf area indexes
• Runoff curve number crop category
• Runoff curve number ratio table
• Soil management
• Water management
• Plant available water in the root-zone
• Dates of irrigation
• Equivalent depth of preplanting irrigation to be applied

5. Erosion database

• Erosion factor dates (for events such as thaw, chisel, harvest, freeze)
• P factor (practice)
• Smoothness factor
• Soil loss ratio

Data sources and availability:

• Soil data are available from the NRCS State Soil Survey Database (SSSD), although not all countis are available. To be used in NAPRA, the Representative Value Generator is needed to produce soil attribute values calculated from ranges of values in the SSSD component and layer tables. Several other programs are used to convert data to NAPRA format.
• Climate data are provided by the NRCS National Water and Climate Center. The data are stored in Climate Data Access Facility (CDAF) Database.
• Pesticide toxicity data are complied from USEPA database and other published data.
• Pesticide physical property data are from the USDA-ARS Pesticide Properties Database.

NAPRA output reports:

NAPRA uses the pesticide fate model GLEAMS to produce annual data which is based on selected scenarios of soils, crop rotation, tillage, pesticide management and climate, etc. Annual pesticide outputs include:

• Maxium 4-day runoff (ppb)
• Total concentation in runoff (ppb)
• Total mass in runoff (g/ha)
• Maximum 4-day percolation (ppb)
• Total mass in percolation (ppb)
• Pesticide associated with organic carbon in soil leaving the field (ppb)
• Total mass associated with soil leaving the field (g/ha)

For more information about NAPRA, please contact Da Ouyang. You may also look at a couple of sources via Internet:

NAPRA developer: NRCS, USDA at Massachusetts.

NAPRA Web version developed by NRCS, USDA at Indiana and Purdue University.

Return to our NAPRA web page or the IWR Internet Homepage.