Research Questions

Stakeholders generated a large number of questions about nitrogen in California agriculture. We took the entire list of stakeholder questions and synthesized them into overarching research questions relating to nitrogen biogeochemistry, on-farm practices, policy, health, and communications. We aim to answer these questions in the assessment.

Synthesized Questions


  • What are the relative contributions of different sectors to N cycling in California? What are the relative amounts of different forms of reactive nitrogen in air and water?
  • Are measurements of gaseous losses and water contamination accurate? Do they capture the “hot spots” and “hot moments”?

Management Practices

  • What are the current N rate recommendations?  Are current nitrogen application recommendations adequate for current cropping conditions?
  • How is nitrogen use efficiency determined and what are the most efficient and inefficient production systems?
  • Are there current management practices that would increase N use efficiency?  What are the “BMP”s for reducing N pollution and increasing efficiency?
  • Are there tradeoffs between reduced N application and other cropping considerations?  Will deviating from current N applications (e.g., form, rate, timing) affect product quality, increase pest pressure, etc? 

Economics & Policy

  • What would the impacts of policies regulating N use be on: farm profits; food prices; and rural economies?
  • What is the cost of N management—to growers, and to society—in terms of public health costs and costs related to environmental contamination?
  • How might policy be used more effectively to both monitor and address non-point source ag pollution?
  • What are the hurdles to having a coordinated and cohesive N policy across regulatory jurisdictions?


  • What is the state of knowledge on how nitrogen influences air and water quality and impacts human health?


  • How do we communicate the complexity of the nitrogen cycle and
    nitrogen-related problems to the public?
  • Will N outreach tools be created that will aid decision making at the field and policy level and educate the public?

Stakeholder Question Tree

Question Tree jpg
A graphical representation of questions the N assessment will answer.

Download the question tree [PDF]

List of original stakeholder questions [PDF]