2020 Climate Action and Agriculture Symposium
Information and documents related to the 2020 Climate Action and Agriculture Symposium Webinar featuring information on current climate trends and agricultural impacts, soil health and updates about related projects in San Diego and neighboring counties.
Featured Organizations and Programs:
- San Diego County Farm Bureau
- Spadra Farm, California State Polytechnic University, Pomona
- CDFA-Healthy Soils Program
- Composting Resources, County of San Diego
- Resilient Roots: Climate Smart Agriculture & Food Systems,
Climate Science Alliance
- Carbon Farming, Resource Conservation District of Greater San Diego County
- Solidarity Farm
- San Diego County Food Vision 2030, San Diego Food Systems Alliance
Technical Reports and Resources:
Compost and Mulch Market Study, County of San Diego (PDF Download,2.1 MB)
by the County of San Diego and Hidden Resources
Mulch Resources from Ben Faber, Ph.D., UCCE Farm Advisor (PDF Download,994 KB)
Questions and comments always come up about the use of mulch in orchards. Mulch has its benefits and drawbacks and they need to recognized in order to manage it. It serves to combat erosion and root rot, but it can also burn. Mulch and wood piled up against tree trunks and near trunks can cause damage to those trunks. A Fillmore grower actually goes through the orchard with a blower to move mulch away from trunks when alerted to fire. On the other hand, irrigated orchards have been shown to be effective at suppressing fire encroaching on homes. And mulches can suppress weeds and reduce water use, but it's possible that importing material for mulch can introduce weeds.
So where to read more about fire? Check out some of the blogs from the past.
Mulch and green waste applied to orchards
- Green Waste, Yard Waste, Whatever You Call It- It has Simple Rules for Use
- A Safer Source of Inexpensive Orchard Mulch
- Avocado planting holes
- Cellulase Production by Various Sources of Mulch
- A Caution on Free "Compost/Mulch"
- A Safer Source of Inexpensive Orchard Mulch
- Mulch, Avocados and the Home Garden
- Mature Compost Does NOT Kill Phytophthora
- Use of Mulch in Organic Orchards Called into Question
Mulch and Landscapes
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:
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:
Map of elevational changes in Ventura County and how
In a recent post about lemon shape being affected by high temperatures
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.
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.