We know that productive garden soil contains between 100 million and 1 billion bacteria per gram (about a teaspoon full). We also know that many of these bacteria have important roles to play in the Soil Food Web and are to a great degree orchestrated by plants through plant root exudates. What we don't know is what roles many of the different bacteria play. We know about a small fraction of them that help with nutrient cycling, disease suppression, and are important to water dynamics in the soil but the greater number by far and their related interaction with other organisms is currently beyond our understanding. In 2007, Christopher Lowry, a neuroscientist now at the University of Colorado found that certain strains of soil-borne bacteria sharply stimulated the human immune system. One bacteria, however, Mycobacterium vaccae, has been found to have amazing benefits to us directly.
Mycobacterium vaccae, a bacteria that is common in soil, has been found to activate a specific group of neurons in our brains that produce serotonin. Serotonin is found in the brain and the blood and is a very important neurotransmitter which helps regulate a whole host of functions including:
Many antidepressants work by serotonin pathways or serotonergic systems. Antigens derived from the bacteria, which is non-pathogenic and saprophytic in nature, altered stress-related emotional behavior in mice. The tests and results of studies in London and Bristol showed that the bacteria caused an increase in serotonin metabolism within the prefrontal cortex. The conclusions from the 2007 studies included "a novel hypothetical framework for investigating the relationships among immune activation, serotonergic systems, and mental health." This added to previous work showing "unexpected improvements in quality of life scores" to clinical cancer and inflammatory disorder trials. Another trial using the soil bacteria to treat psoriasis showed Mycobacterium vaccae "gave long-lasting clinical benefit to most patients, with minimal side effects."
Related to M. vaccae are two scary bacteria: M. leprae and M. tuberculosis which cause leprosy and TB. M. vaccae, named after the cow, however, because it was first isolated from cow manure, is ubiquitous in fertile soil and thrives anywhere soil is enriched with organic matter. Christopher Lowry said that the effect of M. vaccae is "basically no different from all the SSRIs". This is exciting: SSRIs are antidepressants and include medicines such as Prozac, but whereas SSRI's are considered "blunt instruments" by many scientists for treating mood disorders, M. vaccae are selective and specific in their ability to excite certain neurons that produce serotonin and directly impact cognition and mood regulation as well as increase the ability to cope with stress and anxiety.
In a 2008 article in Psychology Today, Daniel Marano explains that eating antioxidant-rich fruits and vegetables may only be half of a newly evolving story of health and that our society's displacement from the natural world has disrupted a deep and direct connection we have to the soil and it's resident organisms. Indeed, the sharp rise in chronic asthma, inflammatory bowel disease, and other inflammatory, allergic, and immune disorders has resulted in "The Hygiene Hypothesis". The bottom line is that we as a society have gotten too clean and the recent obsession with sanitation and anti-microbial products has caught up to us. It's clear that we are a part of the Soil Food Web and removing us from the soil is to our detriment!
Not only does M. vaccae promote the generation of serotonin in our brains, but also norepinephrine.
Perhaps more important, it induces the neurogenesis, or creation, of more neurons that produce these two amazing compounds in our brains. Norepinephrine is just as important as serotonin and affects the amygdala part of the brain where attention responses are controlled, including the "fight-or-flight response and related heart rate, glucose release, and blood pressure responses. Norepinephrine plays a large role in attention and focus and may be used for indications of attention-deficit/hyperactivity disorder, depression, and hypotension.
Similar to the striking rise in allergic and inflammatory disorders, the rise in ADHD and Depression and the related increase in the use (and abuse) of drugs such as the psychostimulants Ritalin or Concerta as well as tricyclic antidepressants or newer SNRI's such as Effexor and Cymbalta point towards a modern society who's young kids do not get to play in the soil enough and one who has abused the use of antibiotics. It would seem that exposing ourselves and especially our children to the soil in the garden could be a good thing indeed. The Hygiene Hypothesis page in Wikipedia now has 39 references as well as plenty of supporting articles for further reading and external links. It "has become an important theoretical framework for the study of allergic disorders" and both their increase since industrialization as well as their higher incidence in more developed countries lends credence to the theory which was first given a scientific background by David Strachan in 1989 and later made popular in the 2005 book by Richard Louv called "Last Child in the Woods: Saving Our Children from Nature-Deficit Disorder." This is now a movement called No Child Left Inside and a Federal bill introduced to the House of Representatives on April 22, 2009, Earth Day. The bill is currently languishing in a subcommittee on early childhood education due to opposition from a conservative american "think tank" called The Heritage Foundation.
It is now clear that exposure to bacteria, and especially during neo-natal development helps to adequately develop regulatory T cells. In 2007, Keven Becker of the Gene Expression and Genomics Unit at the National Institute on Aging wrote an article that supports a link to Autism, also on the rise, to the hygiene hypothesis and shows etiological links between autism, asthma, and inflammation disorders. He hypothesizes that "immune pathways altered by hygiene practices in western society may effect brain structure or function contributing to the development of autism."
More recently, Dorothy Mathews and Susan Jenks of the Sage Colleges in New York tested live mice by feeding them live M. vaccae and found that they could "navigate a maze twice as fast and act with less demonstrated anxiety behaviors as control mice". Mathews said in a May 25 2010 Science Daily article that "learning environments in schools that include time in the outdoors where M. vaccae is present may decrease anxiety and improve the ability to learn new tasks." This is a pretty good reason to promote school gardens!
So what then, do all these medical maladies have to do with gardening, horticulture, and landscaping?... the point here is that we as organisms co-evolved on this planet along with and as a part of the soil ecology over millions of years. Over the past 100 years or so we have become increasingly detached from the soil that supports us and our efforts to further cut us off from bacteria and microbes by the use of antibiotics and antibacterial products has led to increases in diseases and disorders. It's time we realize the health benefits of our natural connection to the Web of life and rejoice in the practice of getting dirty. The next time you breath in the steamy aroma of fresh turned earth, compost, and manure, think of all the wonderful biology making it's way into your personal ecosystem. Contemplate the increased biodiversity you now harbor and be glad. While there are still valid concerns over other bacteria such as certain strains of Escherichia coli, for the most part, the little soil that sticks on the fresh veggies you eat may actually be covered in organisms that are very good for you. -Yet another great reason to grow your own food and if you don't have one, start a garden today!
Now we've all heard about how organic material breaks down into humus. Humus is the not-so-secret component of "Black Gold"... that earthy well composted organic material that binds soil particulates into aggregates, makes gardeners proud and teary eyed to behold, and feeds our precious soil food web. Humus is broken down into two distinct kinds: active humus and stable humus. Many fertilizers contain a mined humate called Leonardite, the result of thousands of years of the decomposition of ancient freshwater marshes. For the longest time, humic acids were thought to be the main carbon constituent of soils. Now, after breakthrough research by Sara Wright in 1996 and further study by her and others, what might be the soil's most important component has been identified.
Most people have now also heard about Mycorrhizal fungi -fungi that extend and improve plant root's abilities to breakdown, make available, transport, and absorb many minerals and nutrients that would not otherwise be available to the plant were it not for this symbiotic relationship. Once the spores germinate, these fungi can only survive about three days before they must become associated with plant roots or they perish. Many organic fertilizers contain inoculants of these amazing organisms and their benefits can be dramatic. They are broken down into two groups: Endomycorrhizae and Ectomycorrhizae. Endomycorrhizae, as the name implies, grow and can produce spores inside the roots of plants and Ectomycorrhizae, which coat the outside of the roots of some plants.
It has also been known that the soil food web is to a large part orchestrated by plants. This is done through plant root exudates, the study of which is still in it's infancy and our understanding is, and may remain, very limited. When you consider the importance of soil bacteria, realize that there are an estimated 60,000 species, most of them having not yet been named, studied, or their role understood, and then think of the growing list of plant root exudates that help orchestrate their behavior, you start to appreciate the intricate web we are delving into. This is a good moment to feel awed at the complexity of an ecology we so often take for granted. Just as it was amazing for us to realize that the overwhelming majority of plant tissue is not derived from the soil, but from the air ( CO2) and water (H2O), it is likewise amazing to realize that a large portion of the hydrocarbons produced by plants through photosynthesis are not held in the plants, but exuded through their roots into the soil food web! The area around the roots where all this action takes place is called the rhizosphere. It's not so surprising then, to think that the endomycorrhizae fungi might likewise also have exudates.
What if I told you that there was a substance in the soil... a substance that was produced by certain fungi in symbiotic relationships with plants... that hold one of the main answers to our planet's health and is able to combat global warming? As Landscapers and Gardeners we're in a position to both appreciate and play a big part in increasing the amount of glomalin in our soils. Amazingly, this material makes up a whopping 27% of soil carbon! Depending on heat and moisture, glomalin can last from seven to twenty-four years. Many soil microbes only last for 20 minutes. fungal hyphae may last from days to weeks. The durability and longevity of glomalin makes it very important for soil health and as a carbon sink. As a glycoprotein, carbon is stored in both it's sugar component and it's protein component, making it 30-40% carbon, up to 24 times as heavy as humic acids, and soils can contain four times as much glomalin as humates! It provides more nitrogen and carbon to the soil than do hyphae or other soil microbes and can be found in quantities of over 100 mg/g in some soils. It's durability is also the reason it took so long to identify it. To find glomalin, you must put a soil sample in a bath of citrate and then heat it at 250 F for an hour!
Glomalin is named after the order of fungi that produce it: Glomales. This Arbuscular mycorrhizal fungi creates glomalin in order to give rigidity and strength to it's hyphae so as to better bridge gaps between soil particles and to help transport soil solutions. As the older hyphae outlive their short lifespan, and new hyphae are produced near the root tips, they release the glomalin in the soil. It's interesting to note that tilling soil greatly reduces the amount of glomalin in soils. Also interesting is that higher concentrations of CO2 in the air promotes rapid glomalin production. This may be one of the major (and overlooked!) feedback loops the Earth has to regulate CO2 content in our atmosphere -and yet another reason to be awed and amazed by the abilities of plants! Between a 3 year study on shrubs and a 6 year study on grasses in San Diego, Wright and scientists from Riverside and Stanford showed that when CO2 levels reached 670ppm (the level we will attain by 2050 given current trends), Glomales hyphae grew three times as long and glomalin production increased 500%. Wright says that the same increase can come from good soil management techniques. Longer hyphae can help plants reach and absorb more water, protect soil from erosion, and increase the fertility of soils. These are all important traits for plants to survive in a warming climate.
Why is this not headline news?! Here we have a major component of healthy top soil- the precious material that we all depend on for our survival, perhaps a key feedback loop in regulating our planet's CO2 levels, and an element of soil fertility that may prove more important to our future in the long run than the Haber process of fixing ammonium nitrate. This discovery is fifteen years old and yet when I ask my fellow gardeners and landscapers if they've heard of glomalin, I get raised eye brows and an inquisitive look... This has to change. This knowledge is precious. Hats off to Sarah and her team! I hope you all go out and include glomalin in your discussions regarding soil fertility and carbon sequestration.
(photo by Sara Wright)
Fall is here and it's time to address the veggie garden. Fall is, in most locations, the best time to think about re-organizing, planning, and scheduling your upcoming crops. It is also the best time to get manure and compost into the garden, plant perennial crops, vines, and trees, as well as adding a fresh layer of mulch. Most gardeners don't get to the dreamy planning stage of gardening until late December when all is dormant, days are short, and the seed catalogs have come... but that's really too late for this winter's crops and even for getting a head-start on next spring. Below I've put together some ideas for consideration:
Putting the Garden to Rest:
Traditionally, the gardener had two options... let the land go "fallow", or put in a "cover crop". Here in Marin we've got more options- and for this we're grateful, but we now know that the "fallow" option is not a good one, no matter where you garden. Leaving soil bare invites erosion and depletes the soil biological diversity and activity. At the very least, a heavy layer of organic mulch should be applied so the earthworms and the rest of the remaining soil ecology has some food, is protected from temperature extremes, and hopefully, the possibility of either water or wind erosion is reduced as well as reducing any wind-blown weed seeds from germinating.
A better solution would be to use a cover crop. A "green manure" crop, as they're sometimes referred to, is generally a mix of a legume and a winter grass; the legume helping to add nitrogen and the grass to increase Organic Matter,"OM", in the form of cellulose -hydrocarbons. The legume would increase nitrogen through a symbiotic relationship with the bacteria Rhizobia that inhabit the roots of the plants and fixes nitrogen from the atmospheric nitrogen found in air within the pore spaces of the soil. A legume cover crop can add around 80 lbs of nitrogen per acre. The other concept is that the "rhizosphere" is kept alive... we now know that plants have co-evolved with various ecto- and endo- mycorrhizae fungi that help them breakdown, transport, and uptake nutrients into their roots in exchange for sugar. These populations of fungi plummet when the living root matrix is removed from the soil ecology. Keeping a crop in the soil helps maintain increased and balanced populations of beneficial fungi, bacteria, and other soil organisms. Vetch and Rye is a good combination of a legume and a grasse, as are other blends incorporating clover or beans. Fava beans are a favorite as they can also be eaten (edamame) and also grow to impressive size which is good for weed suppression and for younger gardeners who are impressed and inspired by the plants.
In the home garden, space and time is usually limited and the three to four weeks that most cover crops take to decompose after being tilled or disked under is too long to wait. This can be easily remedied by harvesting the cover crop for the compost and putting finished compost back in it's place. This way, the garden returns to production, the soil ecology maintains good populations, and the compost gets a big burst of nitrogen and organic matter to heat it up. This makes no sense, of course, if you're dealing with any sizable agriculture, but the typical back yard raised bed and compost systems can benefit from the quick switch. That having been said, one must really think about other options before devoting precious soil space to a cover crop. Legumes should be part of a regular crop rotation program anyway, and most crops can provide a ready supply of organic matter for the compost. In addition, ready-made compost is now available from local suppliers who are working diligently to reduce the amount of green waste going to the landfill. Supporting our local resource recovery and composting facilities is important and many now offer certified organic composts at very reasonable prices.
Adding compost to the soil is most important in the fall. Our winter rains stir up the earthworms and other soil biota and the organic matter is converted into active humus, releasing more nutrients, and helping to build better soil structure for the following season's crops. Humus is the glue that holds the texture of the soil -sand, silt, and clay- together into soil aggregates and allows for better tilth -increased soil pore space that equates to increased aeration, water infiltration, and water holding capacity. If budget allows, for the small home garden, adding bulk compost and continuing with productive food crops might make the most sense, keeping the available space alive, active, and productive year-round.
Heat:
Fall and Winter Crops are all about night-time and soil temperatures. Not much happens when everything goes below 50 degrees. One can think about the Winter garden as a huge outdoor refrigerator, keeping greens, tubers, and stems fresh for harvesting or overwintering for a head start on spring. The trick is to get your crops far enough along to be able to harvest throughout the coldest days and then keep the beds warm as long as possible and protect the plants from extreme conditions -prolonged frosts and pounding wind and rain.
Raised Beds help a lot. By just adding regular helpings of Organic Matter -"OM" and digging, the planting beds will naturally be higher than the paths in between. Just a few inches may make the difference between frosted and non-frosted plants. Raised beds can help add much more height and warmth, not to mention a great framework for garden organization, helping to schedule crop rotations, intercropping, succession planting, and companion planting programs. They also help reduce compaction as they are designed to eliminate the need to walk on the garden beds. Raised beds also form a good framework on which to apply cold frame "lights" to help protect plants in the worst of conditions. Here in Marin, there is generally more damage done from inadequate venting of cold frames -they can get really hot even in the winter!, but wax-based pistons can help automate this task and reduce the risk of cooking the plants you are trying to save from frost. The ideal top day-time temperature in a cold frame is in the 60-65 range... perfect for the plants to harden off and prepare for the cooler nights ahead.
One tool in our toolbox for frost (and pest!) protection is the floating row cover. These fine spun fabrics can go right over the crops, or be suspended by metal or pvc hoops, wires or poles, to protect most crops from a number of various pests along with protection from frost. (Think camping in a tent vs. out in the open on bare ground...) They are fine enough to allow light and water to penetrate, but still offer protection -usually 4-8 degrees difference. I've also found these especially helpful in mitigating the effects of leaf miners on chard, spinach, and other brassica plants, not to mention birds, raccoons, and even pets. When things get really cold, shade cloth and burlap tarps an also add layers of protection. In those dire situations where we dip below freezing, all these measures, along with irrigation, can work synergistically to keep fresh greens on your menu.
Biology equals heat. As a side note, I've heard of many stories of fresh manure and straw being placed below raised beds to keep them warm as well as chickens being used as a heat source for greenhouses. Frost protection is an open playing field for the gardener with ingenuity and persistence. Routing the dryer vent into a greenhouse might make a lot of sense.
Hygene vs. Habitat:
Winter is the traditional time to clean up the garden and eliminate sources of fungal spores and such from reintroducing themselves to next season's growth. While this makes sense, one has to take the whole Web into consideration and think about how the beneficials will overwinter. Our biological buddies are out there working at reducing our pest populations naturally and for free. Eliminating their winter food and habitat will be at our loss the following season. The old system of stripping the land bare, burning the pile of debris, and starting over in spring has given way to a new paradigm of knowing our pests and their natural predators, and promoting healthy populations of beneficial organisms that, along with proper cultural techniques, keep pest populations in a low, stable population that is below our acceptable threshold but high enough to support the population of beneficials. With this in mind, for example, it IS important to make sure that rose and peach leaves get removed and composted -to reduce various fungus diseases from completing their life cycle- but it might be good to leave some of the herbs as well as some composite and umbelliferous plants in place to allow for parasitic wasps to have a nectar source. Be on the lookout for Lacewing eggs, aphid mummies, and other signs of our natural garden helpers. A healthy and biologically diverse garden ecology will remain healthy while a bare bones sterile environment is a prime candidate for pest explosions in the spring.
While on the topic of pests... our first rains around Halloween also mean the start of our mollusk season. While this may not be as exciting as the deer or duck season to some hunters, snails and slugs can be easily trapped in citrus rinds, various trap crops, or killed outright with iron phosphate... an ingenious use of an effective bait that is also a fertilizer -and not toxic to pets, kids, or the environment when used as directed. This is especially true for those acid loving plants that tend to become iron deficient in alkali situations. Placing a meager bounty on the heads of these one-footed foes can also entice children to scour the garden for spare change. Again, know thy pest and where they hide.
Mud and Darkness:
As the garden gets closer to the Winter solstice, two elements help keep the gardener away: The mud and the dark. Both these problems can be easily solved: Address the garden paths in the early Fall and add a key tool to the garden tool box: a head lamp. Adding a fresh layer of wood chips, rice straw, or some other mulch -with a layer of cardboard or weed fabric if needed/desired, can quickly eliminate the mud -and the reluctance to venture quickly out there to cut greens and herbs. Likewise, a lightweight headlamp hanging by the door along with your pruners can eliminate the other hinderance to winter gardening and open up a whole new world for those who get home from work after dark and "can't" garden...
The Plants:
I've identified over 25 good candidates to consider for the Fall/Winter garden but I'm going to save this for a follow up Blog. Those of you in Marin who are interested in this topic and missed my two recent Seminars at Sloat Garden Center can hear more on this subject this Thursday at the Marin Art and Garden Center for the first Continuing Education event of the Marin Mater Gardener Program. It starts at 6:30.
Gardening has evolved. Today it's not uncommon for people to wait years on a waiting list for an opportunity to get a small plot in a community garden in which to partake in the heady emotions and both psychological and physical benefits that come from a direct connection to our Earth mother along with the priceless feelings of having tasted the contentment that can come from that connection as well as the knowledge that one has been a good land steward here on the planet, connected with the community, and produced healthy nutritious food for one's self, one's family, and one's friends and neighbors. These benefits are truly life changing, utterly basic in their ability to fulfill the needs of the human condition, and yet so precious as to be rare on the planet in this post industrial age.
Once one gets a garden plot, where to begin? How does one maximize these benefits? The food is surely secondary. The feelings achieved from digging fresh compost into a plot, the knowledge of increasing the biodiversity, the tilth, and the humus content of the soil along with all the good negative ions, beneficial bacteria, and insects that one can attract is intoxicating. The new gardening camaraderie of your fellow gardeners is also where it's at in terms of basic feelings of well being and right livelihood. Luckily, our species has been at this for quite some time, co-evolving alongside our photosynthetic friends, molding them to our liking through breeding and hybridizing programs that stretch back beyond recorded history, and we are now the beneficiaries of this heritage heirloom knowledge.
All the tricks to success, once one gets past acknowledging the soil food web mentality, tend to favor the saving of both space and time. Moderns science now tells us that the two are one and the same and yet together they make up the fabric of reality as we experience it. To the gardener of a small plot with a busy schedule, however, space and time can become the limiting factors of how much priceless benefits one can glean from their gardening experience. Even though it may seem we are going fast, we are no where near the speed of light, and our mass will not be bending the fabric of space-time any time soon. Below are some simple and yet time-tested strategies for saving both time and space in a small garden plot:
Succession Planting: This operates like clockwork. Our climate here in Marin allow us to garden in a prolonged season that can accommodate multiple seedings, setting out of starts on successive dates, and a prolonged harvest. This is especially true of baby green crops and short lived corps. Tables that describe the "days to maturity'" or "days to harvest" can be consulted for planning this for the greatest benefit. Seeding every two weeks for most greens is a good start.
Intercropping: Some plants grow fast, some slow. Some plants take up more space later in their lifespan. Some plants do better when shaded and protected by other plants. Growing two crops in one area can greatly increase the productivity of a given plot of soil. Lettuce and onions along with a quick radish crop are classic examples. There are many more.
Companion Planting: Some plants can actually benefit others by providing nutrients, attracting beneficial organisms, or repelling unwanted pests. A good example would be how marigolds inhibit the root knot nematode that affects tomatoes. Another might be how blooming cilantro (coriander) can attract parasitic wasps that keep aphids in check.
Crop rotation: Traditionally the four square garden rotation of root, fruit, grass, and legumes has proven successful. Now, rotating plant families is used to help maintain healthy soil ecologies along with balancing carbon and nitrogen levels.
Row Covers: These spun agricultural fabrics can help extend the growing season as well as protect young crops from birds and other pests such as keeping leaf miners from laying eggs on chard plants -or even keeping dogs and cats out of a newly seeded bed.
Sheet Mulching: All the rage in sustainability gardening, the use of recycled cardboard as a weed barrier beneath a layer of mulch can smother perennial weeds and stop the cycle of annual weeds in one season while improving soil organic mater content and increasing earth worm populations. Less time weeding and more space for desired plants just makes good sense.
Cover Crops: Although it's possible to keep a bed in production year-round here, cover crops are far preferable to leaving land fallow. Soil ecological diversity takes a dive when there's not an active rhizosphere in place. Blends of grasses and legumes can add nitrogen and organic matter -but rather than turning them under and waiting for them to decompose, it's more efficient to compost them and add ripe compost right away, thus keeping the beds alive and productive with minimal downtime.
Drip irrigation and ET based controllers: Here's the big time saver: automatic irrigation. If the time a gardener spends irrigating can be spent gardening, much more can be accomplished. Modern controllers that blend historic averaged evapotranspiration curves with on-site weather data are now affordable and easy to implement, making efficient irrigation possible with little input of our time. Pressure compensating and self-flushing emitters and related advances in in-line drip tubing makes getting water where it needs to be when it needs to be there in just the right amounts a realistic possibility.
Head Lamps: For those of us who have a busy life, juggling jobs and kids, those who need fresh herbs after dark, maintain compost and worm bins after hours, and those who take advantage of our climate to extend the growing season on both ends... modern head lamps can show us the light. Nocturnal feeders are now exposed, daylight is not a limiting factor, and yes, you are now a bona fide garden geek.
The list goes on, but these strategies will save you both time and space, get you closer to the garden nirvana we all crave, and make you a hero around the community compost pile. Go forth, live long, and prosper. I know your garden will. Happy Gardening!
Earlier this month I finally handed in my final exam for the
Marin Master Gardener
program and a week later I got my pin, diploma, and bumper sticker. I had always known I'd go through the program and join the group, but the slowdown in the economy inspired me to go for it sooner (perhaps many years sooner) than I might have, and I'm sure glad that I did. It's a huge time commitment and the Thursday classes were tough to work my schedule around, but the pay-off has been huge and I've really only touched the surface.
Besides the wonderful group of classmates from the 2010 class, there are over 300 Marin Master Gardeners that I'm slowly being introduced to and, of course, they are all proving to be wonderful Marin Gardeners who are passionate about so many of the same things I am. I'm getting more involved with the Marin Art and Garden Center, lovingly referred to as "MAGC", the School Gardens, the County Fair, a local therapeutic garden, and a host of other projects. They also work hand in hand with the MMWD to help our communities save water in their landscapes. Did you know there is a growing organic demonstration farm at the IVC campus?
The resources the Marin Master Gardeners and the good folks at the UC System provide to our community is truly a vast piece of work. The
Cooperative Extension works to get the information of the ANR, the University
of California Division of Agriculture and Natural Resources out to the public. The UCCE has been helping
people solve horticultural problems since 1913 when “Extension Agents”
supervised “Victory Gardens” during the world wars. The Master Gardener Program
was started in King and Pierce counties in Washington State in
1972. The California Master
Gardener Program was started in Sacramento and Riverside Counties in 1980,
followed quickly after by Fresno in 1981.
In 2006, it was recognized as a statewide program and included 36
counties and over 3200 certified master gardeners.
The Marin Master Gardener program was
started in 1986 and Napa county followed in 1995. The list
of Master Gardener County Websites now totals 45. A detailed historical
overview of the Master Gardener Program can be found as a PDF document here. As of 2006, the certified California
Master Gardeners had donated over 1,931,787 hours of volunteer time valued at
over 2.09 million dollars. In
2009, the Marin Master Gardeners donated more than 13,000 hours of volunteer
time to community projects.
The specific Core Values
and Purpose of the Master Gardener Program are as follows:
The purpose of the UC Master
Gardener program (MGP) is to extend research based knowledge and information on
home horticulture/pest management issues to the residents of California. There
are a set of core values that guide the program. These core values are the
criteria for designing and implementing educational activities and measuring
educational impacts. These core values are:
a. UCCE
MGP activities focus on education, not service.
b. Activities
meet identified clientele issues and needs.
c. Master
Gardener Volunteers are guides to learning and respect others’ viewpoints
andabilities.
d. Educational
activities are inclusive, not exclusive.
e. MGs
extend only researched based and technically accurate information.
f. UCCE
MGPs encourage improved environmental quality and sustainable
gardeningpractices.
g. MGs
emphasize “learn-by-doing” methods.
h. MGs
teach new skills, validate achievement, and encourage extending to others.
i. Activities
build community support for UCCE through improved visibility.
Some of the best
resources, besides classes, telephone hotlines, plant clinics, fairs,
horticulture seminars, and demonstration gardens, are websites full of useful
and (fairly) easy to find information.
These websites are open and available to everyone.
The most favored is
probably the UC IPM website. This site is the gateway to a wealth of
information from the technical to the simple on best management practices for
most horticultural issues. The California Gardening
site is also a big winner, but is primarily an easier directory to the IPM
site.
Shortcut links to my
favorite spots on the IPM site are:
Natural Enemies Photo Gallery
(beneficial insects and other organisms who help!)
There are SO many other resources! A full listing can be found on the CommServ, the ANR Communication Services Web Server.
Some good
ones from the Marin site are:
Oak Mortality Task Force (staying up
to date with S.O.D)
Marin Master Gardener Plant
Selector Tool (water needs, deer, wildlife value, etc.!)
A list of Marin Master Gardener
Projects
I'm looking forward to a long and rewarding relationship with my growing network of newfound Master Gardener friends, grateful for the opportunities to give back to the community in so many helpful ways, including opportunities to speak, write, and teach, and very proud to be a part of such a fine program.
(-and now that the training program is over, perhaps I can find time to blog once again! ;-)
Soil fertility is a complex topic. It's one that initially seems simple; what could possibly be complicated about dirt and what plants eat? Especially when one has the background, as I did, coming from a University system that, when I was there in the late 80's, catered to a growing agribusiness mentality and was still entrenched in the mindset of soil testing, charts showing a crop's desired diet, and then adding any elements in short supply in the most economical and directly available way. Don't get me wrong: I strongly advise testing your soil. The problem is that the result of this mindset has been the continued degradation of large tracts of some of our most precious soils using what I would consider to be brutal fertilizers. While these are not generally used in the home garden, they help make a good point: We should be feeding our soils and promoting a healthy soil ecology which in turn takes advantage of the soil's natural ability to hold water, nutrients, and increase good tilth through increased humus content and the resulting aggregation of soil particles. Feeding the plants with fast acting and strong fertilizers can do harm to the soil ecology and over time, reduce the amount of humus, lowering soil fertility.
Anhydrous ammonia, a vapor that has a whopping 82% nitrogen content, can be injected into the soil to boost the amount of yield you get out of each acre. Unfortunately, pumping that much nitrogen directly into the soil, although it can be argued that it DOES increase microbial activity after several weeks, has some side effects that are not so great: The excess nitrogen promotes rapid decomposition of whatever organic matter is in the soil. The acidity of the soil also plummets and is usually neutralized by adding lime -1.8 times as much as the nitrogen added! These reduce soil aggregation and results in compacted soils.
Muriate of Potash, containing up to 60% Potassium also seems like a magic bullet until you realize that it (Potassium chloride) also contains over 47% chloride -salt! Sodium nitrate, sometimes referred to as Chilean nitrate, is also highly saline. Salt degrades aggregation. It also can literally suck water out of plant tissue through osmosis.
So if the "big guns" of conventional fertilizer backfire on us, and the answer instead really lies in building and maintaining humus, the desire to understand what is really going on leads us to the complex web of life in the rhizophere- the magical area surrounding plant roots where interactions of root secretions, microorganisms and mycorhizal fungi- and even interactions with earthworms! The more I learn about this complex system that is always in flux, the more I realize how little we really understand. Instead of the conventional mindset of replacing mineral elements, the new mindset is more like micro wildlife management where we have to supply food for all the organisms, keep them protected from excess solar exposure, erosion, drastic swings in moisture content, pH, or temperature extremes.
Earthworms enjoy a steady food supply. In agriculture this means reducing or eliminating discing, plowing, and tilling, adding manure, growing cover crops, and keeping as much crop residue on the surface as possible. In the garden it means not tilling and adding lots of compost and regular layers of mulch. A happy population of earthworms are said to process 20,000 lbs of top soil per acre per year, increase the water infiltration rate by up to 10 times, and stimulate plant growth (from: ATTRA Sustainable Soil Management by Preston Sullivan)
"... it may be doubted if there are any other animals which have played such an important part in the history of the world as these lowly organized creatures." -Charles Darwin's take on earthworms after careful study.
While we are now shifting our thoughts from supplying nutrients to plants to feeding the soil organisms, we still need to understand and be aware of the nutrients in play. There are a few ways to remember the "essential plant nutrients", but the way I learned it was with the slogan:
"C Hopkins cafe mighty good, but Clara's zany cup has many more!"
This is fairly easy to remember and actually maintains the elements in order of decreasing amounts actually used by plants. Let's break it down:
(-all paraphrased from wikipedia)
Other elements have gotten on the list since I learned this, such as Silicon (cell walls), Nickel (Nitrogen metabolism), Cobalt(Nitrogen fixation in legumes), Selenium, and Sodium.
The Big Three: N P K; Nitrogen, Phosphorus, and Potassium are considered Macronutrients. They are reflected as the three numbers on all fertilizer containers, always in that order. In very broad strokes, fertilizers high in N will cause the plant to grow quickly, putting on vegetative growth. Fertilizers high in Phosphorus will help promote flowers and roots. Fertilizers high in Potassium help with reducing diseases and improving fruit production.
A rule of thumb is that fertilizers higher than a value of 10 in any of the N P K designations is most likely NOT an organic fertilizer. There are a few exceptions where you see a 12 or a 15, but nothing much higher. Inorganic fertilizers are usually in a concentrated form and are more readily available to plants, but they are also leeched out of the root zone quickly. According to the Cooperative State Research, Education and Extension Service, USDA, organic fertilizers "have many advantages". Soil crusting is reduced, water movement and structure is improved, beneficial microbes are fed, and nutrients are more slowly released over time. Some possible problems with Inorganic fertilizers are that it's possible to apply too much at once. Problems with Organic fertilizers noted are related to the possibility of putting on too much non-composted manure and the possible introduction of weed seeds. The real problem with organic fertilizer is that they are generally, per pound of nutrient, more expensive.
"OOOOOOMMMMMM" Organic Matter: Compost Compost Compost! Mulch Mulch Mulch!
Organic matter can come in bulk from regular mulching, or it can be added with compost, composted manures, or specialty organic fertilizers. A discussion of specialty organic fertilizers and some other soil amendments will be posted on the next blog. I'll also be talking about fertilizers on the 20th and 27th at local Sloat Garden Centers, Sunday, 10am.
I have been pondering lately about just how cool plants are -again! I've written about this in the past but was inspired to revisit the topic on this blog while listening to Glenn Keator, an engaging local author, educator, and plant enthusiast, discuss plant biology with the Marin Master Gardeners. It dawned on me how fortunate we are to be able to be so intertwined in the lives of so many plants and to be privy to the growing information regarding plants and plant lore. But it goes deeper than that. Our day to day relationships with plants as gardeners make us appreciate plants for the beauty they provide and we go about our roles of propagating, pampering, growing, and combining them in artistic and useful ways. But how often do we contemplate on how much we have in common and how much we owe it to plants for our very existence?
Vascular plants have been here on Earth, indeed, actually involved in the Earth’s evolution, for approximately 440 million years. There are approximately 350 thousand species of plants. We as gardeners know that many species are divided up into dozens of cultivars. The diversity is astounding. It’s cool to think that this many species have a whole energy system that is somewhat opposite that of ours: Plants use carbon dioxide to synthesize glucose and give off oxygen as a waste product. We use oxygen and glucose and give off carbon dioxide as a waste product. What goes around comes around.
Plants have evolved to accept light at two specific wavelengths. At these bluer and redder wavelengths, Chlorophyll molecules absorb light in the chloroplasts and we see them in the spectrum of what is not absorbed -green. Humans have been on the earth about 200 million years -less than half as long as plants. We are only now figuring out how to capture the energy of sunlight using photovoltaics. Thank goodness plants have been at it for such a long time. About 4.4 billion years ago our atmosphere was mostly carbon dioxide and water vapor -and almost no oxygen. Although the cyanobacteria started producing oxygen about 3.5 billion years ago, when the photosynthesizing plants evolved, the atmosphere changed dramatically and eventually the carbon dioxide got locked up in limestone, shells, and fossil fuels. This allowed oxygen breathing organisms to evolve. Now that we’ve been using those fossil fuels for a short while we’ve had to acknowledge the inconvenient truth that it creates more carbon dioxide in the atmosphere -and global warming. All the oxygen in the atmosphere also allows the creation of a layer of a special allotrope of oxygen that protects us from much of the suns ultraviolet radiation -the ozone layer. Also inconvenient is how our recent use of chlorofluorocarbons has reduced the number of these special types of oxygen and have allowed a growing amount of genetic damage to living organisms, including us. As I said, what goes around comes around.
The oxygen put into the atmosphere by plants also reacted with the ammonia from all the early volcanos and formed the nitrogen that now makes up 75% of our atmosphere and is the basic building block of all living tissues and amino acids. It’s the first number on any bag of fertilizer. What’s really amazing is that nitrogen can’t be used directly by plants or animals. Plants are part of a network though. Certain bacteria can use nitrogenase enzymes to “fix” ammonium into nitrites, which is then converted by other bacteria into nitrates, finally usable by plants to eventually form proteins, amino acids, and alkaloids. Some plants have even assimilated the useful nitrogen fixing bacteria into a symbiotic relationship in their roots as in the case with legumes, which makes up a large part of our diet. Most of our livestock feeds and pasture forage plants are legumes. Other plants do this too. I was surprised to find out that one of my favorite plants, Gunnera, also has a symbiotic relationship with a nitrogen fixing bacteria. So do Casuarinas, Myricas, and lichens. The real wonder of nitrogen, however, is when you put four of them in a ring, as in Chlorophyll.
Glenn brought up a fascinating bit of information to ponder: the similarities between chlorophyll and hemoglobin. In mammals hemoglobin makes up 97% of red blood cells (dry weight) and is the carrier of oxygen from lungs (or gills) to the rest of the body. It also is important in neurons and as an antioxidant in kidneys. In Hemoglobin, an iron ion is surrounded by four nitrogen in a plane, the iron being able to bind with oxygen and translocate it. In Chlorophyll, it's a magnesium ion that is similarly surrounded by four nitrogens. These amazing molecules are both produced through the same metabolic pathways and are called Porphyrins; coordinated with iron: you get the building blocks of our blood, coordinated with magnesium and you get the building blocks of our photosynthetic friends. Interestingly, but not surprisingly, very similar structures also create bacteriochlorophylls, other photosynthetic pigments that various bacteria use to absorb other wavelengths of sunlight -even sulfur based bacteria. These amazing similarities between the chemical workhorses of the biological world always inspires a sense of wonder in me, and at the same time a strong sense of oneness, -of connectedness; ourselves being so similar in basic structure to plants and even bacteria.
Just to leave Nitrogen as a basic building block really doesn’t tell the whole story, though: Nitrogen, along with a diverse group of bacteria and fungi, are also the basis for decomposition. Where do you think we’d be without decomposition? Talk about circular events. As gardeners we all know the wonders of compost. And what do we balance in the compost pile? Moisture, oxygen, nitrogenous material, and carbonaceous material. And where do you think the carbonaceous material came from? Plants, of course! The amazing evolutionary trick that plants pulled off was to develop cell walls. Animal cells only have a plasma membrane. Plants get a cell wall. By combining Hydrogen from water with Carbon from carbon dioxide, again using the amazing chlorophyll in photosynthesis, they can make carbohydrate frameworks: cellulose, by far the most abundant form of living terrestrial biomass. Plant cell walls consist of several layers of cellulose microfibrils held together with hydrogen bonds that allow high tensile strength and ... wood. Now where would us landscapers be without wood? Would our species have evolved at all?
So everything you breath, everything you eat, every hydrocarbon in your body -and every other body, big, small, human or otherwise- is the result of plants. We may think we are higher on the “food chain”, but perhaps we should think of it more like a tall pyramid with us precariously balanced at the top. The more solid foundation is made up of plants, bacteria, and minerals. The “carbon cycle” trumps the “food chain” any day anyhow, and it’s based on plants. When you think of all the bacteria and enzymes involved, then we’re looking at a Web. And when you sit out this summer warming yourself in the sun, or find yourself in the hot sun working in a garden, think about all the plants around you using that energy, turning those photons into sugars, breaking the chemical bonds of water, and be jealous. Be very jealous. I wish I could do that! Maybe I’d look good in green too. Now that we are “building green”, “voting green”, and “living green”, desperately trying to undue the mess our opposable thumbs and enlarged cerebral cortexes have gotten us into, it’s good to reflect on our fine photosynthetic friends and appreciate them not only for their beauty and usefulness, but for allowing us the ability to be here, use our senses, and appreciate anything in the first place. It sure is nice to know we are a part of the “green industry” and that our species has now acknowledged the Web and the importance of green. It's also really nice to know we're so closely related.
"All things share the same breath -the beast, the tree, the man... the air shares it's spirit with all the life it supports" -Chief Seattle
(chemical structures from Wikipedia- I love the Web!)
Promoting Sustainable Landscape Practices and Good Land Stewardship
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