The Southern San Joaquin Valley Management Practices Evaluation Program (MPEP) is developing and compiling online tools and resources for growers.
The Crop Yield to Nitrogen Removed Calculator (also known as the Y-to-R Calculator) estimates N removed (R) and the ratio of N applied (A) to N removed (A/R). Results can be calculated on inputs for a single crop or for multiple crops. Conversion factors were developed by UC Davis (Geisseler 2016) based on the best available information. The conversion factors will continue to be refined as additional research becomes available.
The N supply in irrigation water is a crucial component of N management. This calculator allows users to calculate N supply from inches of applied water and N (nitrate and/or ammonium) content from surface and/or groundwater.
Management Practice Performance (MaPP) Decision Support
Tool (in development)
This online interactive tool will allow irrigators to select a location and crop, and evaluate management options from the standpoint of the relative risk of N loss through leaching from the root zone. Irrigated landscapes vary greatly with respect to the degree of difficulty in retaining N in the root zone for use by crops. The performance of various combinations of management practices applied to a specific crop is influenced by soil, climatic, topographic, and other agronomic factors. MPEP modeling efforts will assess common sets of management practices across the full range of Central Valley conditions.
This site is a compilation of outreach events related to agricultural management practices in the Central Valley.