UC Cooperative Extension researchers will discuss best irrigation and nutrient management practices tailored specifically for young orchards in the San Joaquin Valley.

Growers invited to discuss young almonds, pistachios, walnuts, olives and citrus orchards starting May 9

To help growers manage irrigation and nutrients for young and immature orchards, UC Cooperative Extension is offering workshops in Modesto, Merced, Fresno and Bakersfield. 

The workshops will feature presentations by various experts and researchers focusing on best irrigation and nutrient management practices tailored specifically for young orchards in the San Joaquin Valley. They will cover almonds, pistachios, walnuts, olives and citrus.

“Attendees will gain insights into the irrigation and nutrient needs of young orchards, which are different from those applicable to mature orchards, and learn strategies for adjusting these practices as orchards mature,” said Moneim Mohamed, UC Cooperative Extension irrigation and soils advisor for Stanislaus, San Joaquin and Merced counties. “This knowledge aims to ensure healthier tree development, better resource use and more resilient orchards in the face of climate change.”

Moneim Mohamed, UCCE irrigation and soils advisor, will discuss water and nutrient management in non-bearing walnuts.

Growers, certified crop advisers and other agricultural professionals are encouraged to attend. Workshop attendees may request one-on-one assistance from a UCCE farm advisor.

Speakers include UCCE advisors Mohamed, Mae Culumber, Tobias Oker, and Cameron Zuber, UCCE specialist Giulia Marino, Andre Daccache of UC Davis, Charles Hillyer and Shawn Ashkan of Fresno State.

The Young Orchard Irrigation and Nutrient Management workshops will be held in four locations: 

Modesto 

Charles Hillyer and Shawn Ashkan of Fresno State will discuss water and nutrient management in young citrus.

May 9 (8 a.m.–12:30 p.m.)
UC Cooperative Extension, Room HI, 3800 Cornucopia Way

Register at https://ucanr.edu/orchardsmodesto

Merced

May 14 (8 a.m.–12:30 p.m.)
UC Cooperative Extension, 2145 Wardrobe Avenue

Register at https://ucanr.edu/orcharsmerced

Fresno

May 22 (8 a.m.–12:30 p.m.)
Fresno State, 5370 N. Chestnut M/S OF 18

Register at https://ucanr.edu/orchardsfresno

Bakersfield

June 5 (8 a.m.–12:30 p.m.)
UC Cooperative Extension, 1031 South Mount Vernon Avenue

Register at https://ucanr.edu/orchardsbakersfield

Workshops are free and include coffee breaks, lunch, workshop materials along with the presentations. Registration is required. 

These workshops are supported by a grant from California Department of Food and Agriculture and sponsored by Almond Board of California, California Pistachio Research Board, WiseConn Engineering and Irrometer Company, Inc.

Growers will need to implement best management practices that reduce nitrate leaching losses on the Central Coast to comply with Agricultural Discharge Order 4.0.  The use of drip irrigation has allowed many growers to be efficient with both water and nitrogen fertilizer.  Fertigating through the drip system allows for spoon feeding nitrogen in amounts matching the pattern of crop N uptake, and to place fertilizer in the root zone.  Tools like the soil nitrate quick test and the online irrigation and nutrient management platform, CropManage, can help farm managers accurately determine the right amount of fertilizer to apply to satisfy crop N requirements without jeopardizing production.

Once the right amount of fertilizer to apply has been determined, it is important that irrigators have the tools that they need to accurately inject the correct volume into the drip system. Fertigation trailers usually consist of a nurse tank that can hold a maximum volume of 500 to 1000 gallons of fertilizer and are equipped with a small gas or electric pump used to inject liquid fertilizer into the drip system.  Often irrigators rely on markings on the side of the nurse tank to determine the volume of fertilizer that they are injecting.  These markings are usually not accurately calibrated nor have fine enough graduations to precisely measure out fertilizer volume.  Furthermore, tank markings can be hard to read, especially if the trailer is not level. 

A flowmeter could increase the precision of metering fertilizer into a nurse tank or for measuring the volume of fertilizer injected into the drip system.    Using a flowmeter for metering fertilizer would also facilitate tracking the volume of fertilizer applied to each crop by either noting the meter readings or by interfacing the flowmeter to a datalogger that can record the application volumes.   

We evaluated the accuracy of three models of flowmeters designed for metering liquid fertilizer:  1. Banjo FM100 meter, 2. Dura-meter, and 3. Blue White F-1000 (Fig. 1).  Each model relies on a different mechanism to monitor fertilizer volume. The Banjo meter measures flow using a magnetic sensor, while the Dura-meter uses a nutating disk, and the Blue white meter uses a small propeller.  The accuracy of the flowmeters was tested using 25 gallons of either water, ammonium nitrate (20% N), or urea-ammonium nitrate (32% N).  A testing manifold was set up in the UCCE Monterey greenhouse that pumped a calibrated volume of each fluid through the flowmeters using an electric diaphragm pump.  Five or more test runs were made for each meter and fluid.  The average volume measured and standard deviation from the mean volume was calculated.   

Figure 1. Three models of flowmeters that use different mechanisms for measuring flow were evaluated for accuracy in measuring the volume of fertilizer pumped from a tank.

All three models of flowmeters accurately measured water and fertilizer volumes (Table 1).  Measurement errors were generally less than ±2% of the true volume.  The Dura-meter which uses a nutating disk to measure volume was the most accurate flowmeter of the three models and had an overall average absolute error of -0.2 gallons per 25 gallons measured, and a coefficient of variation of ±0.3%.  The Blue White meter, which uses a paddle wheel to measure volume, was least accurate and had an overall absolute error of 1 gallon per 25 gallons measured and a coefficient of variation of ±1.3%. The type of liquid metered affected the accuracy of the Banjo and Blue White meters more than the Dura-meter. 

Table 1.  Accuracy of flowmeter measurements of water and two types of liquid fertilizer (AN20 and UAN32).

Although the Dura-meter was most accurate of the three flowmeters, it did require an initial calibration before testing began.  The other meters could not be manually calibrated.  The nutating disk mechanism directly measures volume of a liquid which may explain why the Dura-meter was not affected by the density of the liquid tested.   Both the paddle wheel and the magnetic sensor mechanisms used in the Blue-White and Banjo meters indirectly estimate flow rate.  Another advantage of the Dura-meter was that it was the cheapest of the three meters when the tests were conducted.  Another version of the Dura-meter can be used to turn off an injection pump when a specified volume of fertilizer has been injected.  This version is available as part the auto batch system (Dura-ABS™).  The Banjo meter is also available in a model (MFM100) the can output an electrical pulse proportional to flow rate so that volume of fertilizer injected can be recorded on a datalogger.

Conclusions

Three commercially available flowmeters were demonstrated to accurately measure fertilizer.  Either of these meters could help irrigators more precisely apply the intended volume of fertilizer to a crop as well as verify and maintain records of the fertilizer volumes used to grow each crop.  Depending on the practices of the growing operation it may be more efficient to install the meters on either the nurse tank trailer or the main fertilizer tank.  If the nurse tank is used for injecting fertilizer at several fields during the day, then installing the meter on the trailer would be logical, but if the nurse tank is only filled for a single field at a time, the flowmeter could be installed on the main fertilizer tank.   

Eduardo Blumwald, right, of the UC Davis Department of Plant Sciences, with postdoctoral researcher Akhilesh Yadav, and rice they and others on the Blumwald team modified to use nitrogen more efficiently. Photo by Trina Kleist, UC Davis

Discovery could reduce nitrogen pollution, save farmers billions

Researchers at the University of California, Davis, have found a way to reduce the amount of nitrogen fertilizers needed to grow cereal crops. The discovery could save farmers in the United States billions of dollars annually in fertilizer costs while also benefiting the environment.

The research comes out of the lab of Eduardo Blumwald, a distinguished professor of plant sciences, who has found a new pathway for cereals to capture the nitrogen they need to grow.

The discovery could also help the environment by reducing nitrogen pollution, which can lead to contaminated water resources, increased greenhouse gas emissions and human health issues. The study was published in the journal Plant Biotechnology.

Nitrogen is key to plant growth, and agricultural operations depend on chemical fertilizers to increase productivity. But much of what is applied is lost, leaching into soils and groundwater. Blumwald's research could create a sustainable alternative.

“Nitrogen fertilizers are very, very expensive,” Blumwald said. “Anything you can do to eliminate that cost is important. The problem is money on one side, but there are also the harmful effects of nitrogen on the environment.”

A new pathway to natural fertilizer

Blumwald's research centers on increasing the conversion of nitrogen gas in the air into ammonium by soil bacteria — a process known as nitrogen fixation.

Legumes such as peanuts and soybeans have root nodules that can use nitrogen-fixing bacteria to provide ammonium to the plants. Cereal plants like rice and wheat don't have that capability and must rely on taking in inorganic nitrogen, such as ammonia and nitrate, from fertilizers in the soil.

“If a plant can produce chemicals that make soil bacteria fix atmospheric nitrogen gas, we could modify the plants to produce more of these chemicals,” Blumwald said. “These chemicals will induce soil bacterial nitrogen fixation and the plants will use the ammonium formed, reducing the amount of fertilizer used.”

Blumwald's team used chemical screening and genomics to identify compounds in rice plants that enhanced the nitrogen-fixing activity of the bacteria.

Then they identified the pathways generating the chemicals and used gene editing technology to increase the production of compounds that stimulated the formation of biofilms. Those biofilms contain bacteria that enhanced nitrogen conversion. As a result, nitrogen-fixing activity of the bacteria increased, as did the amount of ammonium in the soil for the plants.

“Plants are incredible chemical factories,” he said. “What this could do is provide a sustainable alternative agricultural practice that reduces the use of excessive nitrogen fertilizers.”

The pathway could also be used by other plants. A patent application on the technique has been filed by the University of California and is pending.

Dawei Yan, Hiromi Tajima, Howard-Yana Shapiro, Reedmond Fong and Javier Ottaviani from UC Davis contributed to the research paper, as did Lauren Cline from Bayer Crop Science. Ottaviani is also a research associate at Mars Edge.

The research was funded by the Will W. Lester Endowment. Bayer Crop Science is supporting further research on the topic.

Editor's note: Blumwald is affiliated with UC Agriculture and Natural Resources through the Agricultural Experiment Station at UC Davis.