Inspection Services Blog

Research Update: California Fertilization Guidelines

Research Project: Online Fertilization Guidelines for Agricultural Crops in California

Project Leaders: Daniel Geisseler (CE Nutrient Management Specialist) and William Horwath (Professor), Department of Land Air and Water Resources, University of California, Davis.
Project Status: Completed
Project Location: Statewide

Issue: California grows over 400 commodities that account for one-third of the country’s vegetable production and two-thirds of the country’s fruit and nut production. For many of these crops, there are various research and technical articles available that provide fertilization information. However, this information is often hard to find and can take hours of searching the web. California needed a comprehensive overview of current research-based knowledge of crop fertilization. The Fertilization Guidelines have addressed this need by providing a summary of relevant nutrient management research on major California crops.

Findings: California Fertilization Guidelines Guidelines were first published in the summer of 2013 and covered 16 crops. This project expanded the Guidelines to cover an additional 12 crops (see below). Nutrient management quizzes, for many of the crops, have also been added to the website.

Screenshot of fertilizer guidelines web site

Potential Impact: The California Fertilization Guidelines provide growers and crop advisors with an important decision-making tool to help determine the right time, place, rate and source of fertilizers without compromising crop yield. With the addition of these 12 crops, the guidelines now provide nitrogen, phosphorus and potassium fertilization information for 28 crops covering 75 percent of irrigated agriculture in California.

Additional Resources: FREP publishes nitrogen management brochures based on these guidelines. If you would like to make specific crop brochures available at your next event or wish to hand them out to clients, customers or workers, high-quality PDFs and a limited number of printed brochures are available from FREP upon request. PDFs of the brochures are available on the FREP Resources page.

Guidelines website:

Final Report:

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