Understanding Decision-Making of Citrus and Raisin Grape Growers and Adoption of Nitrogen Management Practices

Understanding Decision-Making of Citrus and Raisin Grape Growers and Adoption of Nitrogen Management Practices is an MPEP project with University of California Davis to quantify the current use of improved practices and characterize drivers of grower behavior to enhance future research, education, and outreach programs in the SSJV. Note that citrus and raisin grapes are two commodities that are disproportionately represented in the SSJV, relative to other parts of the Central Valley. Therefore, work on these commodities is a high priority for the SSJV MPEP.

Adoption of improved nitrogen (N) management practices will in some cases be essential to meet groundwater quality protection goals. However, more information is needed about the rate of practice adoption, and about barriers to more extensive adoption. This project aims to quantify the current use of improved practices, and to better understand what drives grower decisions. This knowledge will in turn help to enhance future research, education and outreach programs.

Project Leaders


Budget and Funding

The overall budget for this project is $75,000 over two years, come from the MPEP Committee’s Conservation Innovation Grant (funded by NRCS). This funding is primarily for staff support and travel. Collaborators are providing in-kind contributions, and have supplementary funding for complementary work in areas further north. Additional grant funds to expand work in the Southern San Joaquin Valley may be sought.


Adoption of N management practices by California growers is in some cases needed to reduce N movement into groundwater while maintaining economically viable cropping systems. Research over the past decades has identified promising practices to retain more fertilizer N in the root zone for use by crops. These practices include the use of N budgets to balance N inputs and outputs for individual field units; implementation of the “4R’s” (right rate, time, place, and source) to guide fertilization strategies; the use of leaf and soil N sampling for verification of crop nutrient status and residual soil N; appropriate integration of fertilizers/fertilization with irrigation; enhancing soil health to improve nutrient retention; and deployment and operation of high-frequency, low-rate (drip and micro-irrigation) systems for efficient water use. Yet there is insufficient understanding regarding the current rates of practice adoption, and barriers to adoption.


This project aims to (i) develop an understanding of the status of N management practice adoption by citrus and raisin grape growers of ; (ii) determine the challenges and benefits on grower decision-making; and (iii) identify the key incentives and barriers to enhanced adoption of improved management practices. This information will inform stakeholder groups, including water quality coalitions, UC Extension, certified crop advisors, State Water Boards, commodity groups, Cooperative Extension, NRCS, and others to inform policy-making and grower outreach where needed to improve N management.


  1. Develop a quantitative understanding of adoption of N management practices for citrus and raisin grape growers in the regions represented by the SSJV MPEP Committee.
  2. Distribute, collect and aggregate survey data from grower members in SSJV MPEP regions by way of focus groups. Quantify current practice adoption (full/partial, permanent/ temporary) and determine effects of growers’ decisions on adoption of N management practices.
  3. Analyze responses to determine key grower motivations and barriers to adoption of N management practices. Validate survey responses by crosschecking with coalitions.
  4. Communicate findings directly to grower populations surveyed, as well as to academic and industry groups, to inform management, as well as outreach and education programs.


Collaborating with water quality coalitions and industry stakeholder groups will streamline grower participation and enhance investigators’ ability to interpret results. To maximize grower participation, all results will remain anonymous. The approach includes developing a survey questionnaire in collaboration with stakeholders and working with grower focus groups at various venues. The process will allow for a high degree of crop and grower specificity. Contact with 25 percent of the survey populations, a 60-percent response rate per focus-group meeting, and 100 participants per meeting, are all goals. Results will feed into coalition-wide recommendations.

Practices that are most widely applied for each commodity will be identified, along with challenges and benefits to adopting practices, and sources of information that influence grower groups’ opinions of N management practices.

We will develop descriptive analyses of compiled results and emerging trends from interviews and focus groups. We will use multi-level, hierarchical modeling with random effects and factor analysis, of survey response data to determine key variables influencing grower decision making and rate of adoption of N management practices for each commodity (Summer 2018).

Results from this proposal will be compared with additional efforts by Lubell and Brown, where other water quality coalitions have been surveyed. Our aim is to take the results of this work and develop them into a broader, Valley-wide survey.

Final Report

Find the Final SSJV Barriers to Adoption Report here.

For more Information

For more information about the Barriers to Adoption Project, contact the MPEP project leaders:

Ms. Charlotte Gallock
Coordinator, SSJV MPEP Committee
Kings River Water Quality Coalition

Dr. John Dickey
Technical Program Manager

Dr. Ken Cassman
Senior Agronomic & Soils Advisor

UC Davis Project Leaders:

Sat Darshan S. Khalsa
Assistant Project Scientist
Department of Plant Sciences
University of California Davis
Patrick H. Brown
Department of Plant Sciences
University of California Davis