Subtropical Fruit Crops Research & Education
University of California
Subtropical Fruit Crops Research & Education

Posts Tagged: soil

CDFA Grant Help

Introducing your new information source for CDFA grants,

Kern County and Ventura County

Shulamit Shroder and Alli Rowe are two of the newest members to UC Cooperative Extension. Shulamit is based out of Kern County and serves Kern, Tulare, and King Counties. Alli is based out of and serves Ventura County. Both specialize in the climate smart agriculture initiatives from the California Department of Food and Agriculture. They provide technical assistance for the SWEEP, AMMP, and Healthy Soils grant programs.

-          The State Water Efficiency and Enhancement Program (SWEEP) encourages farmers to install more efficient irrigation systems that decrease their water consumption as well as their greenhouse gas emissions. You can apply for a SWEEP grant for up to $100,000.

-          The Alternative Manure Management Program (AMMP) awards funds - up to $750,000 - to livestock producers who decrease their methane emissions by changing the way that they manage manure.

-          The Healthy Soils Program incentivizes the implementation of conservation agriculture techniques that decrease erosion and greenhouse gas emissions, like cover cropping, compost, crop rotation, and mulching. For this grant, there is $75,000 available per project.

Keep an eye out for future announcements about grant deadlines - they have all passed but should reopen within the next year, pending further funding.

For more information about these programs and for help applying for these grants, please contact Shulamit or Alli at:

Shulamit Shroder: or 661-868-6218

Alli Rowe: or 805-645-1464



Posted on Friday, June 7, 2019 at 6:13 AM
Tags: cdfa (4), soil (23)

Controlling Soil pH with a Grass?

This is an intriguing article that popped up about how to improve blueberry production in alkaline soils.  High pH soils are a major issues for many of our tree crops along the coast.  pH is what controls the availability of most plant nutrients and what bacteria and fungi grow in the soil, creating the biosphere.   So can growing a grass cover crop in our orchards improve lemon and avocado production?

A lawn is better than fertilizer growing healthy blueberries

Intercropping with grasses is an effective and sustainable alternative to chemical treatments for maximizing blueberry yield and antioxidant content in limey soils.


Blueberries are prone to iron deficiency - and correcting it increases their health-enhancing antioxidant content, researchers have discovered.

Published in Frontiers in Plant Science, their study shows that growing grasses alongside blueberry plants corrects signs of iron deficiency, with associated improvements in berry quantity and quality. The effects are comparable to those seen following standard chemical treatment - providing a simpler, safer, cheaper and more sustainable strategy for blueberry farming on sub-optimal soils.

What do superfruits eat?

All soils are rich in iron, but nearly all of it is insoluble.

"Most plants get enough iron by secreting chemicals that make it more soluble," explains senior study author Dr José Covarrubias, Assistant Professor of Agriculture Sciences at the University of Chile. "These iron 'chelators' can be released directly from the roots, or from microbes that grow among them, and allow the iron to be absorbed."

"Blueberries, however, lack these adaptations because they evolved in uncommonly wet, acid conditions which dissolve the iron for them."

As a result, most of the world's relatively dry or alkaline ('limey') cropland is unsuitable for optimal blueberry growth.

"Iron is essential for the formation and function of plant molecules like chlorophyll that allow them to use energy," Covarrubias continues. "That's why iron deficiency shows up as yellowing leaves - and drastically reduces plant growth and yield.

"And in blueberries, iron-dependent enzymes also produce the 'superfruit' antioxidants responsible for their celebrated blue skin and health-enhancing effects."

Strong blueberries must pump iron - but at what cost?

There are two approaches to correcting iron deficiency in blueberries: acidify the soil, or add synthetic iron chelators. Each has its drawbacks, says Covarrubias.

"The commonest industrial approach is soil acidification using sulfur, which is gradually converted by soil bacteria into sulfuric acid. The effects are slow and difficult to adjust - and in waterlogged soils, hydrogen sulfide might accumulate and inhibit root growth.

"Acids can also be added directly via irrigation systems for more rapid acidification - but these are hazardous to farmers, kill beneficial soil microbes, and generate carbon dioxide emissions.

"A commoner strategy among growers is application of iron bound to synthetic chelators - often sold as 'ericaceous fertilizer' - but these are very expensive and leach potentially toxic chemicals into the water table."

A cheaper, safer alternative is needed for efficient large-scale blueberry production. Thankfully, one already exists.

"Grasses - which are well-adapted to poor soils - can provide a sustainable, natural source of iron chelators via their roots when grown alongside fruiting plants. Intercropping with grass species has been shown to improve plant growth and fruit yield in olives, grapes, citrus varieties - and most recently, in blueberries."

A grassroots approach to sustainable blueberry farming

Now, Covarrubias and colleagues have brought intercropping a step closer to the mainstream of blueberry cultivation.

For the first time, they measured the effects of different methods of iron chelation on antioxidant content and other fruit qualities in blueberries.

"In an orchard of 'Emerald' blueberry bushes cultivated in alkaline (pH 8) soil, we compared the effects of five different iron chelation treatments: a 'gold-standard' synthetic iron chelator (Fe-EDDHA), intercropping with grass (common meadow grass or red fescue), cow's blood (Fe-heme), or no treatment (control)."

"We found the association with grasses increased not only the total weight and number of blueberries per plant, but also the concentration of anthocyanins and other antioxidant compounds in their skins, compared to control. The effect sizes were comparable with the proven synthetic chelator Fe-EDDHA, whereas applications of Fe-heme from cow's blood - a fertilizer commonly used in home gardens - had no significant effect."

The beneficial effects paralleled improvement in the plants' iron status (leaf color), which was also comparable between the grass-associated and the Fe-EDDHA-treated plants. None of the treatments had a significant effect on average berry weight

Turf is ready to roll out for healthier blueberries

A potential limitation of intercropping observed in the study was a decrease in berry firmness, since firmer berries are favored by consumers.

"The association with grasses decreased berry firmness compared with control plants, whereas the berries collected from plants treated with Fe-EDDHA reached intermediate values.

"However chemical analysis showed a non-significant trend towards increased ripeness in the berries collected from the intercropped plants, which could account for this small difference."

Intercropped plants also required an additional water supply to maintain a similar soil moisture to other treatments, but plant management was otherwise straightforward and the same across groups. The grasses were kept cropped between 5 and 15cm - a typical range for an attractive mown lawn.

"Our findings validate intercropping with grasses as a simple, effective, sustainable alternative to standard iron correction strategies in blueberries," concludes Covarrubias. "Both commercial and private growers can put this strategy to use right away to boost their blueberry crop and antioxidant content."


Please link to the original research article in your reporting:

Frontiers is an award-winning Open Science platform and leading Open Access scholarly publisher. Our mission is to make research results openly available to the world, thereby accelerating scientific and technological innovation, societal progress and economic growth. We empower scientists with innovative Open Science solutions that radically improve how science is published, evaluated and disseminated to researchers, innovators and the public. Access to research results and data is open, free and customized through Internet Technology, thereby enabling rapid solutions to the critical challenges we face as humanity. For more information, visit and follow @FrontiersIn on Twitter.

soil colors
soil colors

Posted on Tuesday, April 2, 2019 at 11:17 AM
Tags: acid (2), alkaline (2), avocado (280), citrus (323), nutrients (21), pH (6), soil (23)

Getting Down and Dirty - Soils Conference

The Soil Science Society of America had its North American Societies Conference (Canada/Mexico/US combined societies) in San Diego this month -

1,700 people came and gave talks.  Lots of talks!!! You can review the topics covered by various categories, such as mineralogy, soil chemistry, microbiology, fire impacts on soil, climate change, soil physics, irrigation management, etc,  etc, etc -

or by what was presented each day -


It's a huge amount of information. By clicking on the session, its possible to see the different speakers and topics and see an abstract of the talk.  For example, clicking on the Monday, 9:30 AM session on Fire in the Landscape:

24-7 Fire Effects on Soil Organic Matter in a Southern Appalachian Hardwood Forest: Connecting the Movement of Fire-Altered Organic Matter in Soil and Aquatic Systems'. Jeff A. Hatten1, Lauren Matosziuk2, Adrian Gallo1, Katherine Heckman3, Kevin D. Bladon4, Lucas E. Nave5, Brian D. Strahm6, Tyler Weiglein7, Jessie Egan8, Maggie Bowman9 and Ryan Stewart10, (1)Department of Forest Engineering, Resources and Management, Oregon State University, Corvallis, OR, (2)Oregon Sate University, Corvallis, OR, (3)Northern Research Station, USDA Forest Service (FS), Houghton, MI, (4)Department of Forest Engineering, Resources, and Management, Oregon State University, Corvallis, OR, (5)University of Michigan Biological Station, Pellston, MI, (6)310C Cheatham Hall (0324), Virginia Tech, Blacksburg, VA, (7)310 West Campus Dr., Virginia Tech, Blacksburg, VA, (8)University of Colorodo Boulder, Boulder, CO, (9)INSTAAR, University of Colorado Boulder, Boulder, CO, (10)Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA


And clicking on the title will give the abstract : 24-7 Fire Effects on Soil Organic Matter in a Southern Appalachian Hardwood Forest: Connecting the Movement of Fire-Altered Organic Matter in Soil and Aquatic Systems'.


So, this is how some organic matter moves through the soil after a fire.  It doesn't all go up into the air as carbon dioxide, some of it actually migrates deeper into the soil and will probably persist there for a long long time.


Or maybe the whole issue of what constitutes a Healthy Soil interests you?  Check out these talks:


Read more about similar and different presentations at the Conference.  The full papers based on the abstracts will be out at some later date once they have been properly reviewed for accuracy.  That usually takes several months to get all of these presentations organized.


soil weathered from sndstone
soil weathered from sndstone

Posted on Friday, January 25, 2019 at 5:10 PM
Tags: soil (23), sssa conference (1), talks (1)

Soil Moisture/Nitrogen Workshop

Irrigation and Nutrient Management Field Day

Monday January 14, 2019
555 Las Varas Canyon Road Goleta 7:30 am - 11:30 pm, lunch is provided The event is FREE

but please register -

Learn all about soil moisture sensor systems -
•     Using sensors to save water, energy, & fertilizer
•     Monitoring & interpreting soil moisture data
•     Checking & fixing common system problems
•     System configurations & funding opportunities
•     Practical and common sense considerations

Attendees get a
FREE Soil Nitrate
Quick Test Kit

The Cachuma Resource Conservation District, with funding from the Department of Water Resources, is
pleased to offer this FREE field day event in partnership with:

Parks Land and Cattle Company The Irrometer Company
Natural Resource Conservation Service

Picture:  Soil Moisture Testing by the" Feel Method"

Posted on Monday, January 7, 2019 at 5:42 PM
Tags: soil (23), testing (4), water (49), workshop (4)

Wild Fire Effect on Soils?

Low-severity wildland fires and prescribed burns have long been presumed by scientists and resource managers to be harmless to soils, but this may not be the case, new research shows.

According to two new studies by a team from the University of California, Merced (UCM) and the Desert Research Institute (DRI), low-severity burns - in which fire moves quickly and soil temperature does not exceed 250oC (482oF) - cause damage to soil structure and organic matter in ways that are not immediately apparent after a fire.

"When you have a high-severity fire, you burn off the organic matter from the soil and the impact is immediate," said Teamrat Ghezzehei, Ph.D., principal investigator of the two studies and Associate Professor of Environmental Soil Physics at UCM. "In a low-severity fire, the organic matter doesn't burn off, and there is no visible destruction right away. But the burning weakens the soil structure, and unless you come back at a later time and carefully look at the soil, you wouldn't notice the damage."

DRI researcher Markus Berli, Ph.D., Associate Research Professor of Environmental Science, became interested in studying this phenomenon while visiting a burned area near Ely, Nev. in 2009, where he made the unexpected observation that a prescribed, low-severity fire had resulted in soil structure damage in the burned area. He and several colleagues from DRI conducted a follow-up study on another controlled burn in the area, and found that soil structure that appeared to be fine immediately after a fire but deteriorated over the weeks and months that followed. Berli then teamed up with Ghezzehei and a team from UCM that included graduate student Mathew Jian, and Associate Professor Asmeret Asefaw Berhe, Ph.D., to further investigate.

Soil consists of large and small mineral particles (gravel, sand, silt, and clay) which are bound together by organic matter, water and other materials to form aggregates. When soil aggregates are exposed to severe fires, the organic matter burns, altering the physical structure of the soil and increasing the risk of erosion in burned areas. In low-severity burn areas where organic matter doesn't experience significant losses, the team wondered if the soil structure was being degraded by another process, such as by the boiling of water held within soil aggregates?

In a study published in AGU Geophysical Research Letters in May 2018, the UCM-DRI team investigated this question, using soil samples from an unburned forest area in Mariposa County, Calif. and from unburned shrubland in Clark County, Nev. to analyze the impacts of low-severity fires on soil structure. They heated soil aggregates to temperatures that simulated the conditions of a low-severity fire (175oC/347oF) over a 15-minute period, then looked for changes in the soil's internal pore pressure and tensile strength (the force required to pull the aggregate apart).

During the experiment, they observed that pore pressure within the soil aggregates rose to a peak as water boiled and vaporized, then dropped as the bonds in the soil aggregates broke and vapor escaped. Tensile strength measurements showed that the wetter soil aggregates had been weakened more than drier soil samples during this process.

"Our results show that the heat produced by low-severity fires is actually enough to do damage to soil structure, and that the damage is worse if the soils are wet," Berli explained. "This is important information for resource managers because it implies that prescribed burns and other fires that occur during wetter times of year may be more harmful to soils than fires that occur during dry times."Next, the research team wondered what the impact of this structural degradation was on the organic matter that the soil structure normally protects. Soil organic matter consists primarily of microbes and decomposing plant tissue, and contributes to the overall stability and water-holding capacity of soils.

In a second study that was published in Frontiers in Environmental Science in late July, the UCM-DRI research team conducted simulated burn experiments to weaken the structure of the soil aggregates, and tested the soils for changes in quality and quantity of several types of organic matter over a 70-day period.

They found that heating of soils led to the release of organic carbon into the atmosphere as CO2 during the weeks and months after the fire, and again found that the highest levels of degradation occurred in soils that were moist. This loss of organic carbon is important for several reasons, Ghezzehei explained.

"The loss of organic matter from soil to the atmosphere directly contributes to climate change, because that carbon is released as CO2," Ghezzehei said. "Organic matter that is lost due to fires is also the most important reserve of nutrients for soil micro-organisms, and it is the glue that holds soil aggregates together. Once you lose the structure, there are a lot of other things that happen. For example, infiltration becomes slower, you get more runoff, you have erosion."

Although the research team's findings showed several detrimental effects of fire on soils, low-severity wildfires and prescribed burns are known to benefit ecosystems in other ways -- recycling nutrients back into the soil and getting rid of overgrown vegetation, for example. It is not yet clear whether the negative impacts on soil associated with these low-severity fires outweigh the positives, Berli says, but the team hopes that their research results will help to inform land managers as they manage wildfires and plan prescribed burns.

"There is very little fuel in arid and semi-arid areas, and thus fires tend to be short lived and relatively low in peak temperature," Ghezzehei said. "In contrast to the hot fires and that burn for days and weeks that we see in the news, these seem to be benign and we usually treat them as such. Our work shows that low-severity fires are not as harmless as they may appear."

The study, "Soil Structural Degradation During Low?Severity Burns," was published on May 31, 2018 in the journal AGU Geophysical Research Letters and is available here:

The study, "Vulnerability of Physically Protected Soil Organic Carbon to Loss Under Low Severity Fires," was published July 19, 2018 in the journal Frontiers in Environmental Science, and is available here:

firefighters in avocado grove
firefighters in avocado grove

Posted on Friday, September 14, 2018 at 6:55 AM
Tags: avocado (280), citrus (323), fire (30), soil (23)

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