Posts Tagged: fertilizer

Growing cereal crops with less fertilizer

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.

Drip-irrigation study sees ‘huge’ reduction in water, fertilizer use for sweet corn

Study by UCCE advisor in Imperial County also shows 5% increase in yield

A new study suggests that drip irrigation for sweet corn can significantly conserve water, reduce fertilizer use and boost crop yield in the low desert of California – and likely in other areas of California with similar conditions.

Although Imperial County is California's top sweet corn-producing county, with about 8,000 acres planted on average each year, irrigation methods for this crop have been rarely studied in this region (or anywhere else in the state), according to Ali Montazar, UC Cooperative Extension irrigation and water management advisor for Imperial, Riverside and San Diego counties.

Montazar conducted a study in the Imperial Valley over two crop seasons, 2020-21 and 2021-22, to demonstrate and quantify the potential benefits of switching to drip irrigation from the more common furrow irrigation method. The study, available in a recent issue of UC Agriculture and Natural Resources' Agricultural Briefs, will be published in a future issue of Vegetables West.

“I'm hoping with this project we can encourage growers to adopt it, because it seems very promising,” said Montazar, noting that drip irrigation is a “new practice” for sweet corn in California.

Among the 11 commercial sweet corn fields in the study over the 2021-22 season, the six that were under drip irrigation used, on average, 37% less water than the five under furrow irrigation. In absolute terms, the drip-irrigated fields saw an average water savings of 2.2 acre-feet per acre; for Montazar, who has studied drip for a variety of crops in the Imperial Valley, that was an astonishing result.

“I've worked with drip on processed onions, lettuce, alfalfa, spinach … we've never seen a figure like 2.2 acre-feet per acre, that's huge,” he said, attributing the dramatic drop-off to the high volume of water required to furrow-irrigate the sandy soil in the Imperial Valley.

More efficient irrigation also means less fertilizer is needed – a boon to the environment and Salton Sea water quality, as well as growers' bottom line. With fertilizer prices continuing to rise, sweet corn growers using drip could see a substantial 25% cost savings on fertilizer expenses – about $150 per acre less – compared to furrow irrigation, according to Montazar's study.

And by relieving plants of the stress from over- and under-irrigated conditions, drip irrigation helps keep soil moisture at its “sweet spot” – resulting in a 5% increase in marketable crop yield for sweet corn in the study.

“When we have a better, more efficient irrigation system, we can maintain soil moisture at a desired level, over time and space,” Montazar explained.

Because the benefits of drip appear to be linked to soil conditions (sandy loam, and other light soils), Montazar believes that this irrigation practice could deliver relatively similar water and fertilizer savings and improved crop yield in other regions across California, regardless of climactic differences.

“If you use drip in any part of the state, you have the benefits of drip – more uniform water application, more uniform fertilizer – that's not related to the desert,” he said. “That's part of the system's potential.”

Montazar plans to follow up on his preliminary study with additional research on sweet corn and drip irrigation during the 2022-23 crop season.

New ‘big data’ tools help California wheat farmers reduce fertilizer guesswork

Growers in California grapple with plenty of climate uncertainty – but a new set of tools can help wheat farmers make crucial fertilizer decisions with more precision and confidence.

An interactive website integrates these tools – developed or adapted by researchers at the University of California, Davis and University of California Cooperative Extension – that provide farmers with recommendations for applying nitrogen fertilizers, specific to their own sites and conditions.

“The system is made for being flexible, for being reactive – and not having a cookie-cutter approach, year-in and year-out, because the weather is not cookie-cutter, year-in and year-out,” said Mark Lundy, UC Cooperative Extension specialist in the UC Davis Department of Plant Sciences.

While factoring in those weather variables, the management tool also draws data from two indicators of nitrogen sufficiency or deficiency: the results of a soil nitrate quick test (a simple test previously used in vegetable crop systems along the coast), and comparisons of plant health in the broader field to that in a “nitrogen-rich reference zone” (a practice originally developed in the Midwest).

Using them in tandem, in the context of California wheat growing, is a novel approach. In a Nov. 4 webinar, Lundy will introduce the use of the nitrogen-rich reference zone, a small area in a field where extra fertilizer is added at the beginning of the season.

“This project is a unique example of digital agriculture at work in an applied setting,” he explained. “We are integrating ‘big data' sources like site-specific soil and weather data, as well as satellite, drone and other sensor measurements into an interactive web interface. This allows users to receive straightforward yet highly customized recommendations from somewhat complex agronomic models.”

Since 2019, agronomists from UC Davis and UCCE have been testing these tools in real-world conditions, with support from the California Department of Food and Agriculture's Fertilizer Research and Education Program and a Natural Resources Conservation Service Conservation Innovation Grant.

The team conducted 11 on-farm demonstrations in fields representing a wide range of agroecosystems, including the Sacramento Valley, San Joaquin Valley, Delta region, and Tulelake Basin.

Fritz Durst, a western Yolo County-based grower who participated in one of the case studies, said that the process of gathering the data was “actually pretty simple” and the tool “eliminates much of the guesswork” for managing nitrogen fertilizers.

“This tool is extremely helpful for me to make decisions about the most efficient and cost-effective method for applying nitrogen to my wheat,” Durst said.

In addition to potentially increasing crop productivity and farmer net-income, the tool can benefit the environment by reducing the amount of nitrate leaching from fertilizer applications, according to Lundy.

“It's not only trying to say how much fertilizer to put down, sometimes it's trying to confirm you don't really need any fertilizer,” he said.

More resources and events related to the Nitrogen Fertilizer Management Tool for California Wheat – including demonstration activities – will appear on the UC Small Grains blog.

Biodigesters turn food into electricity, but can they also create fertilizer?

On a recent late-summer Wednesday, a freight container filled with cases of expired Muscle Milk protein drink awaited unloading at the UC Davis Renewable Energy Anaerobic Digester (READ) while a front-loader scooped heaps of spoiled vegetables into a mechanical processor. Nourished by a diet of assorted food waste from the UC Davis campus and area restaurants and markets, READ harnesses the activity of billions of microbes to produce biogas capable of generating 5.6 million kWh per year of clean electricity for UC Davis.

But a by-product of READ and other anaerobic digesters – the slurry of leftover solid and liquid material, or digestate – has caught the attention of UC Davis researchers interested in “closing the loop” on food production, consumption, and waste. When processed through an anaerobic digester, organic materials like food discards, expired or off-spec food products, or animal manure can be transformed into concentrated biofertilizers and soil amendments that are highly effective and easily applied to crops.

In an interdisciplinary collaboration at the Russell Ranch Sustainable Agriculture Facility, funded by the California State Water Resources Control Board and the California Department of Food and Agriculture, UC Davis faculty and students have developed a pilot-scale process for commercial production of several forms of this biofertilizer using digestate from READ and other nearby digesters. They are also evaluating their effects on yield and other agronomic metrics in corn and tomato field trials – paving the way for farmers and growers to take advantage of a highly sustainable source of plant nutrition.

The challenge and opportunity of fertilizer from anaerobic biodigesters

The digestate from READ and other digester facilities can be applied directly to soil as a fertilizer, but, because it has a limited shelf-life, it usually must be applied to land in the immediate region of the facility. With the input of food waste that can vary widely from day to day, a facility's digestate is inconsistent in texture and composition, making it difficult to transport and apply to fields using common farm fertilizer equipment.

Filtering and drying this digestate, however, results in solid and liquid forms that can be concentrated, homogenized, easily transported, and applied to soil through existing drip irrigation systems or surface spreading equipment.

This process could allow farmers and growers located further away, and working with common irrigation and fertilizer application equipment, to supplement or replace their synthetic fertilizer consumption with biofertilizers from food waste or animal manure.

How do biodigestate products measure up to synthetic fertilizers?

The research, co-led by professor Ruihong Zhang from the UC Davis Department of Biological and Agricultural Engineering (who also designed READ in partnership with Sacramento-based tech company CleanWorld) and Professor Kate Scow from the Department of Land, Air, and Water Resources, developed pilot-scale systems to efficiently and consistently separate the solid and liquid portions of food- and manure-based digestates. The researchers then examined the nutrient composition of the solid and liquid biofertilizer products, finding that biodigestate-based fertilizers contain valuable nutrients and microbes not found in many synthetic fertilizers.

In current field trials, the researchers are investigating the effects of each of the biofertilizer products on crop yield and quality. Their preliminary results show that it is possible to grow irrigated processing tomatoes and short-season corn using biofertilizer products as the sole source of fertilizer. The origin of the fertilizer matters, however – manure-based liquid fertilizer formed additional large particles after the final filtration, creating concerns about clogging the drip irrigation system. The team thinks an environmentally benign chemical sometimes added to manure digesters to clean the biogas may be the culprit of the problem, but future research is needed. The solid biofertilizer pellets they developed show much promise, as they can be applied using existing methods for spreading compost and can be economically transported farther away from the digester.

In addition to better understanding the best processes for producing and using the biofertilizers, further research is needed to understand how much of the nitrogen in each of the fertilizer products is available for uptake by the crop, as well as economic analyses to determine the commercial-scale production and transportation costs. The researchers will be able to narrow in on the agronomic and economic potential of biofertilizers through the upcoming analysis of the yield of the corn and tomato experiment plots at Russell Ranch. The results of a tomato experiment recently showed that the digestate fertilizers produced just as much fruit as a popular synthetic fertilizer.

Interdisciplinary research for agricultural innovations

Russell Ranch, a program of the Agricultural Sustainability Institute, is designed as a shared space for interdisciplinary research and innovation. The biofertilizer research, among other active projects at Russell Ranch, is an example of the fulfillment of that intention. “The soil scientists are learning engineering, the engineers are learning biology, and the biologists are learning about soil,” Professor Zhang remarked.

The exchange also extends beyond the university: a recent UC Davis Biofertilizer Field Day drew attendees from the UC Division of Agriculture and Natural Resources, several public agencies, the agricultural sector, other universities, nonprofits, entrepreneurs, and food processors. If the research continues to illuminate a way forward for biofertilizers, these audiences may fill important roles in bringing this new technology into practice – and in recycling your lunch leftovers back into a more efficient and sustainable food system.

More information: UC Davis READ, Russell Ranch, and the biofertilizer research

The UC Davis Renewable Energy Anaerobic Digester was unveiled in 2014 as the nation's largest anaerobic biodigester on a college campus, and represented a unique private-public partnership. Professor Ruihong Zhang invented the anaerobic digestion technology used by CleanWorld, which developed it into one of the most advanced commercially-available digester systems in the country.

Russell Ranch Sustainable Agriculture Facility is a “living laboratory” for interdisciplinary field research and innovation. Its flagship project, the Century Experiment, measures the long-term impacts of energy, water, carbon, and nitrogen inputs on agricultural sustainability in the flagship Century Experiment.

The biofertilizer research collaboration includes Zhang Lab graduate students Tyler Barzee and Hossein Edalati, Scow Lab postdoctoral researcher Daoyuan Wang, and Russell Ranch manager Israel Herrera. Collaborating institutions include CleanWorld, California Bioenergy, New Hope Dairy (Galt, CA), Fiscalini Dairy (Modesto, CA), and Sacramento Municipal Utility District.

This story en español.

What's in your compost?

For home gardeners, spring is a busy time of year and there’s never a tomato with more flavor than one grown to full ripeness on the vine. But there are also many safety precautions to follow to prevent contamination of fruits and vegetables with pathogens that cause serious food-borne illnesses. 

Michele Jay-Russell, a veterinarian and research microbiologist at the Western Institute for Food Safety and Security (WIFSS) and program manager of the Western Center for Food Safety (WCFS), recently co-authored a study that highlights the need to be aware of the hazards associated with using raw animal manure to fertilize home gardens. (Read full article here.)

The basis for the study began in July of 2010 when a shire mare from a rural Northern California farm was brought to the William R. Pritchard Veterinary Medical Teaching Hospital for treatment of colic. Following protocol, the veterinarians on call screened the horse for Salmonella to avoid infecting other horses during hospitalization. She tested positive and after successful treatment for colic, went home. Her owners then notified the veterinarians that some of their other draft horses were sick as well — all 8 were tested and 6 came back positive for the same Salmonella Oranienburg strain, including the mare that still had the infection. 

Jay-Russell heard about the case from her colleague John Madigan, professor of medicine and epidemiology at the school. The farm’s owners invited Jay-Russell and Madigan to the farm to see if they could uncover the source of the Salmonella infection. They sampled water from horse troughs, manure storage piles, wild turkey feces and soil from the family’s edible home garden where raw horse manure had been used as fertilizer. Each of those locations had a percentage of positive samples over the sampling period from August 2010 to March 2011.

“We showed the owners how to continue collecting samples and provided them with a FedEx number to ship them to UC Davis,” Jay-Russell said. “During that whole time, the garden soil kept coming back positive, which showed that this strain of Salmonella could persist for months.”

While the researchers couldn’t be completely certain about the original source of Salmonella on the farm, they suspect that a recent surge in the wild turkey population on the property introduced the bacteria to the horses by pooping in the horse corrals and in the water troughs. They speculated that the wild turkeys brought the Salmonella onto the property, although they couldn’t rule out the possibility that the birds were exposed on the farm or to other potential sources of Salmonella. 

“What is clearer is that the raw horse manure applied as fertilizer was the most likely source of garden soil contamination,” Jay-Russell explained. “We suspect that the damp climate in Mendocino County may have contributed to the longevity of this bacterium in the soil long after the owners stopped applying the horse manure to the garden. Fortunately, the owners didn’t get sick, but our investigation showed the potential for widespread dissemination of Salmonella in a farm environment following equine infection.”

To promote safe gardening practices, Jay-Russell has teamed with Trevor Suslow, a Cooperative Extension food safety specialist in the Department of Plant Sciences, to speak to groups of small farmers around the state about best practices. They also use a brochure in English and Spanish, “Food Safety Tips for Your Edible Home Garden,” that includes information about safe uses of animal manure and ways to minimize animal fecal contamination.

“It’s good to let people know about the risks and to correct misinformation about ways to treat the compost pile before using it in the garden,” Jay-Russell said. “The biggest take home message from this experience is to be very careful about using manure from sick horses — and to be cautious about offers of free manure — you don’t know what’s in there. Commercial compost should be bought from a reputable source.”

She urges gardeners to take a class and learn how to compost correctly and safely. Each county in California has UC Cooperative Extension advisors and many have Master Gardener programs offering information on food safety.

Additional resources:

Center for Produce Safety

UC Food Safety

 

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