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

Posts Tagged: climate change

Pore Variety Increases Soil Carbon Storage

The more different the root architecture, the greater potential to store more carbon

The greater the diversity of the rooting network, the greater diversity of pores

It's not just the biomass that stores the carbon, it's the diversity of the pores

So plant a greater diversity of plants to increase stored soil carbon

 

EAST LANSING, Mich. -- Alexandra Kravchenko, Michigan State University professor in the Department of Plant, Soil and Microbial Sciences, and several of her colleagues recently discovered a new mechanism determining how carbon is stored in soils that could improve the climate resilience of cropping systems and also reduce their carbon footprints.

The findings, published last week in the scientific journal Nature Communications, reveal the importance of soil pore structure for stimulating soil carbon accumulation and protection.

"Understanding how carbon is stored in soils is important for thinking about solutions for climate change," said Phil Robertson, University Distinguished Professor of Plant, Soil and Microbial Sciences, and a co-author of the study. "It's also pretty important for ways to think about soil fertility and therefore, crop production."

The study was conducted through the MSU Great Lakes Bioenergy Research Center, funded by the U.S. Department of Energy, and the Kellogg Biological Station Long-term Ecological Research program funded by the National Science Foundation, or NSF, and it was supported by NSF's Division of Earth Sciences.

Over a period of nine years, researchers studied five different cropping systems in a replicated field experiment in southwest Michigan. Of the five cropping systems, only the two with high plant diversity resulted in higher levels of soil carbon. Kravchenko and her colleagues used X-ray micro-tomography and micro-scale enzyme mapping to show how pore structures affect microbial activity and carbon protection in these systems, and how plant diversity then impacts the development of soil pores conducive to greater carbon storage.

John Schade, from the NSF Division of Environmental Biology, said the results may transform the understanding of how carbon and climate can interact in plant and soil microbial communities.

"This is a clear demonstration of a unique mechanism by which biological communities can alter the environment, with fundamental consequences for carbon cycling," Schade said.

"One thing that scientists always tend to assume is that the places where the new carbon enters the soil are also the places where it is processed by microbes and is subsequently stored and protected," Kravchenko said. "What we have found is that in order to be protected, the carbon has to move; it cannot be protected in the same place where it enters."

Scientists have traditionally believed soil aggregates, clusters of soil particles, were the principal locations for stable carbon storage.

Recent evidence, however, shows that most stable carbon appears to be the result of microbes producing organic compounds that are then adsorbed onto soil mineral particles. The research further reveals that soil pores created by root systems provide an ideal habitat where this can occur.

Of particular importance are soils from ecosystems with higher plant diversity. Soils from restored prairie ecosystems, with many different plant species, had many more pores of the right size for stable carbon storage than did a pure stand of switchgrass.

"What we found in native prairie, probably because of all the interactions between the roots of diverse species, is that the entire soil matrix is covered with a network of pores," Kravchenko said. "Thus, the distance between the locations where the carbon input occurs, and the mineral surfaces on which it can be protected is very short.

"So, a lot of carbon is being gained by the soil. In monoculture switchgrass the pore network was much weaker, so the microbial metabolites had a much longer way to travel to the protective mineral surfaces," explained Kravchenko.

Robertson said the research may prompt farmers to focus on plant diversity when attempting to increase soil carbon storage.

"We used to think the main way to put more carbon in soil is to have plants produce more biomass either as roots or as residue left on the soil surface to decompose," Robertson said.

"What this research points out is that there are smarter ways of storing carbon than such brute force approaches. If we can design or breed crops with rooting characteristics that favor this kind of soil porosity and therefore that favor soil carbon stabilization, that would be a pretty smart way to design systems that can build carbon faster."

Nick Haddad, director of the Kellogg Biological Station Long-term Ecological Research program, said research that builds from these findings will continue to discover ways to improve the sustainability of agricultural ecosystems and landscapes.

"Long-term research shows surprising ways that a diversity of plants can benefit the microbes needed for a resilient agricultural system," Haddad added.

Read the whole story:

https://www.nature.com/articles/s41467-019-11057-4

soil pores
soil pores

Posted on Monday, July 29, 2019 at 6:22 AM

Which Way Weather?

In 2018 the Ojai Valley Land Conservancy (OVLC) accepted a grant from the Resources Legacy Fund on behalf of Watershed Coalition of Ventura County (WCVC) for a study of projected climate changes in Ventura County.  OVLC contracted with Drs. Nina Oakley and Ben Hatchett, climatologists with the Desert Research Institute (DRI), to evaluate historic climate variability and projected changes in Ventura County.  This information is needed to “paint a picture” of future climate in the watersheds of Ventura County (Ventura River, Santa Clara River, and Calleguas Creek) to support and inform climate change-related decision-making. This study provides important information for the amendment to WCVC's Integrated Regional Water Management (IRWM) Plan

You can find a copy of the report on the DRI website at: https://wrcc.dri.edu/Climate/reports.php.   

To view presentations and other information from the two WCVC Climate workshops conducted with Drs. Oakley and Hatchett in October of 2018, and April of this year please visit:  http://wcvc.ventura.org/documents/climate_change.htm

Some of those most interesting findings for me, are the historical data. For example, data for the years 1896 – 2018, show a tendency toward increasing maximum temperatures over the period, especially the last 10 years (Fig 1.2). But most interesting, is the increasing minimum temperatures (Fig 1.3) as compared to the maximum temperatures. Winter where is thy sting? The 2018-19 winter was the coldest in my memory, with the heater on full time at night, but there was no general frost damage this year. I can remember 1990 and 2007.

Precipitation in the South Coast region exhibits high interannual variability over the period examined. No notable long-term trends are observed (Fig. 1.4). Since approximately 2000, the 11-year running mean decreases, associated in part with the 2012–2019 drought. It is unclear whether this trend will continue in subsequent years.

There's a lot more information in the report.  READ On.

But something to keep in mind, is that we had a terrible heat wave last July, and it could easily happen again.  Growers who had their trees well hydrated before the heat arrived, sustain less or no damage to the trees and much less fruit drop.  Trees that were irrigated on the day it started to get hot, never had a chance to catch up with the heat.  Once the atmosphere starts sucking the tree dry, water movement through the soil, roots and trunk cant keep up with the demand.  Weather forecasting is pretty accurate 3 days out, and if heat is forecast, get those trees in shape.  You can run water to reduce the temperature and raise the humidity in the orchard to reduce transpirational demand which helps some.

Something we  learned last year.  What we saw and what to expect:

https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=27676

 

Map of elevational changes in Ventura County and how

elevation ventura
elevation ventura

Posted on Friday, June 14, 2019 at 6:27 AM
Tags: climate change (6), cold (5), frost (19), heat (6), rainfall (4), temperature (1)

How Wierd Can Lemons Get?

In a recent post about lemon shape being affected by high temperatures 

https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=29443

a grower sent an image of what I thought was  a blurred view of something that was circled.  I responded saying that I couldn't make it out, and a better image should be sent.

The grower resent the image, but this time it was about the long yellow thing in the background that was being asked about.  The tree is planted next to a chile pepper plant and the question was whether the shape was affected by the chile proximity.

The grower had never seen anything like it before and I haven't either.  But rack it up to the high temperature wave during flowering and the rapid fruit growth period and hormones gone amuck.  if temperature extremes become more common, unusual fruit shapes will likely become more common.

 

Posted on Friday, March 22, 2019 at 7:43 AM
Tags: citrus (338), climate change (6), hormones (1), lemon (100)

Different Lemon Shape

Sometimes we don't see things that are not uncommon, but suddenly catch our eye.  A recent lemon harvest of a trial in the Central Valley turned up lots of fruit with enlarged nipples on the stylar end.  These are from a 'Limoneira 8A' rootstock trial.  Not all of of the fruit was like this, but all of the rootstocks had these fruit, so it wasn't a rootstock effect.

On asking around it turns out, this happens in other places, for example on Spanish fruit:

And on Australian fruit:

And even in many normal years and orchards there is some of this special fruit

During the 2018 spring bloom there were several heat waves that hit citrus growing areas.  Dr. Mary Lu Arpaia, UCR Fruit Specialist, surmises that high temperatures make for elongated fruit and quite likely impact cell division at the stylar end, as well.  So the more heat spells during bloom, it's likely that we will see more of this fruit shape.  It's still good to eat.

Posted on Wednesday, March 6, 2019 at 6:34 AM
Tags: citrus (338), climate change (6), heat (6), lemon (100)

How We Think About GMOs

A recent article from the Journal of Agricultural Education explorers how group decisions are often made.

 

CHAMPAIGN, Ill. -- A tiny insect, no bigger than the head of a pin, is threatening to topple the multibillion-dollar citrus industry in the U.S. by infecting millions of acres of orchards with an incurable bacterium called citrus greening disease.

The battle to save the citrus industry is pitting crop producers and a team of agriculture researchers - including agricultural communications professor Taylor K. Ruth of the University of Illinois - against a formidable brown bug, the Asian citrus psyllid, which spreads the disease.

Trees infected with the disease, also called Huanglongbing or HB, bear small, misshapen, bitter-tasting green fruit and often die within five years. Currently, there's no known cure for the disease, which has cost the U.S. citrus industry billions of dollars in crop production and thousands of jobs since it was first identified in Florida in 2005, according to agriculture experts.

Among other solutions, scientists are exploring the possibility of breeding genetically modified trees that are resistant to the disease.

But given the controversy over the safety of genetically modified food, scientists need to know whether producers will adopt this technology and whether shoppers will buy and consume GM citrus fruit.

A recent study, funded by the U.S. Department of Agriculture, provides some encouraging answers.

Ruth was on a team of scientists from several universities that surveyed a representative sample of U.S. consumers and conducted focus groups to better understand American consumers' attitudes about GM food and agriculture.

About half of the 1,050 people who responded to the survey had positive attitudes toward GM science, the researchers found. Nearly 37 percent of the consumers surveyed felt neutral about GM science and 14 percent had negative perceptions of it.

Most of the people who were receptive to GM science were white males who were millennials or younger, the data indicated. They were highly educated - most held a bachelor's degree or higher - and affluent, with annual incomes of $75,000 or greater.

Women, on the other hand, constituted 64 percent of the group with negative feelings about GM science. Baby boomers and older adults were nearly twice as likely to fall into this group. People in this group also were less educated - about half reported some college but no degree.

The findings were published recently in the journal Science Communication. Co-authors of the paper were Joy N. Rumble, of Ohio State University; Alexa J. Lamm, of the University of Georgia; Traci Irani, of the University of Florida; and Jason D. Ellis, of Kansas State University.

Since social contexts influence public opinion on contentious issues, the survey also assessed respondents' willingness to share their opinions about GM science, their current perceptions of others' views on the topic and what they expected public opinion about it to be in the future.

The research team was particularly interested in exploring the potential impact of the "spiral of silence" theory, a hypothesis on public opinion formation that states in part that people who are highly vocal about their opinions in public encourage others with similar views to speak out while effectively silencing those who hold opposite views.

"If people believe the majority of others disagree with them on a topic, they will feel pressure to conform to the majority opinion," Ruth said.

"People aren't going to be supportive of something if nobody else is supportive of it - no one wants to feel like they are different from the group. That's the reality of the world that we live in today."

By contrast, people surveyed who rejected GM science were more likely to express their opinion when they believed others held the opposite view. But people with positive feelings about GM technology were less likely to speak out when they believed others supported it too.

"The way others express their attitude has an indirect effect on what our attitude ends up being," Ruth said. "We might fall in the actual majority opinion about some of these complex topics, but if other people aren't vocalizing their opinions, we don't know that others out there are like-minded.

"Then we start to think 'Well, maybe I should realign my attitude to what I'm seeing in the media.' What we see in the media is just reflective of the most dominant voice in the conversation, not necessarily the majority opinion. And I think sometimes people don't quite understand that."

Like climate change, GM science is among the complex challenges that some researchers call "wicked issues" - societal problems that are often poorly understood and fraught with conflict, even when the public is provided with relevant science and facts, Ruth, Rumble, Lamm and Ellis wrote in a related study.

That paper was published recently in the Journal of Agricultural Education.

"We must have these conversations about these wicked issues," Ruth said. "If scientists let other people who don't have a scientific background fill the void, we're not going to be a part of that conversation and help people make decisions based upon all of the facts."

https://news.illinois.edu/view/6367/750780

To reach Taylor Ruth, call 217-300-6442; email tkruth@illinois.edu

The paper “A model for understanding decision-making related to agriculture and natural resource science and technology” is available online or from the News Bureau

DOI: 10.5032/jae.2018.04224

The paper “Are Americans' attitudes toward GM science really negative? An academic examination of attitudes and willingness to expose attitudes“ is available online or from the News Bureau

DOI:  10.1177/1075547018819935

mandarin trees loaded
mandarin trees loaded

Posted on Thursday, February 28, 2019 at 5:30 PM
Tags: citrus (338), climate change (6), gmo (1)

Next 5 stories | Last story

 
E-mail
 
Webmaster Email: rkrason@ucdavis.edu