The New York Nitrate Leaching Index (LI) is an indicator of the potential for nitrate to reach groundwater. Nitrate, because it is water soluble, moves downward as water percolates through the soil. The extent of percolation depends on soil depth to a restrictive layer, drainage characteristics and precipitation amount and distribution over the year.
The current LI rates leaching potential based on soil hydrologic group (download below) and 30 year average precipitation data from weather stations around NY. Until recently, rainfall data were county-based. The latest version of the LI uses township-based precipitation data, which more accurately reflects precipitation patterns than the previously used county-based precipitation data. The township-based LI is also incorporated into Cropware v2.0. Click on the links below to learn more about the Nitrate Leaching Index.