Nitrogen Fertilization Recommendation 

for Walnut


P.H. Brown and Q.Zhang, Pomology Department, University of California, Davis
Max Stevenson, UC-SAREP program
R.C.Rosecrance, College of Agriculture, California State University, Chico
Funding for this project was provided through the CDFA-FREP program 
and the UC Sustainable Agriculture Program.



This model calculates the N requirement for Walnut production based upon the yield history, current conditions and previous N applications. This model can be used to calculate both timing and rate of fertilizer application required to maintain optimum yield. Site specific information is required for accurate projection of N requirement hence this model should be applied to each distinct management unit (block or field).

    The data used in this model was derived from exhaustive tree-N budget determinations and input from Max Stevenson, BIOS staff Scientist at the Community Alliance with Family Farmers (


This program provides recommendations only and is not intended to be used as the sole source of information for making N fertilization decisions.  Local environmental conditions can have a profound effect of fertilizer demands.  CDFA-FREP and the University of California are not responsible for the accuracy of this model.