The California Department of Food and Agriculture (CDFA) Fertilizer Research and Education Program (FREP) and Western Plant Health Association (WPHA) presented their annual Nutrient Management Conference as a webinar October 28-29. This series of five blog posts links to each conference session and highlights the most common questions asked by the conference audience and presenters’ responses during the Q&A sessions.
Presentation: Practical Advances in Almond Irrigation Sustainability
Presenter: Luke Milliron, Orchard Systems Advisor, University of California Cooperative Extension, Butte, Glen, and Tehama Counties (Presentation link)
This presentation provided an overview of almond irrigation from the on-farm perspective. Milliron used the framework of the Almond Board of California’s Irrigation Continuum. Topics included water requirements, irrigation system performance, applied water, soil moisture, and plant water status. For each of these topics, Milliron discussed the approach to these methods at the fundamental (1.0), intermediate (2.0), and advanced (3.0) level. Consultants have a key role in helping their growers make practical advances in their irrigation sustainability, and this talk will discuss how.
Q: Are there any advancements in remote sensing in sustainable irrigation methods?
A: This is not my field of expertise, but it is important that growers apply basics of an efficient irrigation before transitioning to remote sensing and drones. There is potential for some of the evapotranspiration (ET)-based monitoring and plant-based monitoring using remote sensing and with drone’s technology coming online. I hope to be working with Dr. Mallika Nocco (UC Davis), a new irrigation specialist, on that next year so stay tuned, but make sure you cover the fundamentals first!
Q: Do you take suggestions for the topics that you cover in your Growing the Valley Podcast?
A: Yes, we do, and the best way to reach out is to contact Dr. Phoebe Gordon or I through Twitter.
Q: Can the average farmer keep track of so many things to increase irrigation efficiency? Do the growers need to hire another specialist to help with their irrigation?
A: There are some large farms that have hired specialists to manage their irrigation systems but for medium-size and small-size farms there is a potential to get help from PCAs and hopefully Certified Crop Advisors (CCAs) to improve their irrigation.
Presentation: Practical Advances in Almond Nutrition Sustainability
Presenter: Dr. Franz Niederholzer, Orchard Systems Advisor, University of California Cooperative Extension, Yuba, Sutter, and Colusa Counties (Presentation link)
This presentation focused on sustainable almond nutrient management in the current buyer’s market. Nitrogen, potassium, phosphorus, zinc and boron management were reviewed. Questions for future research in sustainable almond nutrition were presented.
Q: How much boron is typically recommended and how do we decide when to apply? And is there a risk for boron leaching?
A: Hull tissue sampling and analysis for boron at harvest is the way to decide whether you need to apply boron. If the analysis shows under 80 ppm it’s boron deficit, 120 to 150 ppm is adequate, and over 300 ppm is toxic. In the Sacramento Valley, Yolo County Cash Creek, and west side of San Juaquin Valley the soil has excess boron and there may not be a need for application. Your hull boron content would indicate these levels. The target is 120-150 ppm boron; the current recommendation is 4 pounds of actual boron per acre in a fall spray or pink bud. Do not apply after pink bud and full bloom application is risky to yield set. That would be about as much boron as a good crop could take up, although there might be a need to supplement boron later in the season. I don’t have a recommendation on how to apply, but it can be either applied through fertigation or fall foliar spray, which is more efficient. Be careful to not over apply boron. While there is potential for leaching, it depends on the permeability and texture of that soil.
Q: Why are nitrate fertilizer sources emitting less nitrous oxide than the ammonium and urea sources?
A: Nitrous oxide emissions can happen during denitrification in saturated soils but can also happen during the nitrification process when ammonium is converted to nitrate. If you apply nitrate instead of ammonium, you are reducing the risk of nitrous oxide emission through the nitrification process.
Q: Despite your presentation that N use efficiency is improving, there is an increasing acreage of almond production. Consequently, this may lead to higher load of N associated with almond production. Do you think this is painting industry in a bad light?
A: The evidence suggests that N fertilizer is moving in the vadose zone below the root zone and could leach to groundwater. It is a major issue for industry and the more we know the better we can improve. It’s something that industry needs to be aware of and work on. It cannot be fixed overnight but it should be a major focus of growers’ practices.
Question for both Franz and Luke
Q: As we are dealing with challenges of nitrate leaching where do we start? Water or fertilizer?
Luke: Water has a role, and it is important to consider 4Rs as you plan your irrigation and fertilization. For example, you can leach nitrate while you are leaching the salt.
Franz: Nitrate leaches with excess water. You can manage excess irrigation water during the growing season, but you cannot manage the rainfall during the winter. This means you have to manage your fertilization to prevent excess N in the soil during the winter. There is also a high risk of leaching nitrate in the spring with excess irrigation water.
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For more than 25 years, FREP has presented its pioneering fertilizer research at annual conferences. Since 2007, FREP has collaborated with the Western Plant Health Association (WPHA) to create a conference that balances technical research with discussion on practical application. Presenters from academia, industry, and agricultural consulting provide general and technical information, current research and data, and practical applications addressing statewide and regional nutrient management issues. Visit the Annual FREP/WPHA Conference webpage for links to all the 2020 conference sessions and the 2020 Conference Proceedings booklet.