by Tom Gibson

(This is the inaugural installment of what we at Gardenopolis Cleveland hope will become an ongoing series.  Have you read something in a gardening book or blog or article that made you want to try something new?  How did it work out for you? We’re looking for short, pithy articles not only from editors, but from you, the reader.)

Garden Experiment #1: Sorghum-Sudan Grass

One of the garden “stars” in Michael Phillips’ book Mycorrhizal Planet is Sorghum-Sudan grass (sorghum sudanese).  This annual grows up to 12 feet tall very rapidly, especially in hot weather, thus creating lots of compostable biomass. But it has two other special virtues: 1) Its roots can provide habitat for up to 50 species of mycorrhizal fungi.  And 2) when mowed, the plant responds by expanding its root mass, sometimes by a factor of two.  That means lots of carbon for microflora to feast on during the next growing season.

If ever soil needed more carbon, it was the garden plot I inherited at the Oxford Community Garden in Cleveland Heights.  Light tan in color, it was clearly more dirt than soil.  Weeds like thistle (that thrive in calcium-and phosphorous-deficient soil) loved it.  Although I reserved one strip of my plot for an attempt at tomatoes (aided by some calcium sulfate and worm castings), I seeded the rest in July with sorghum-sudan grass along with a multi-species, mycorrhizal-based fertilizer with the brand name of Dr. Earth. I bought the latter at Home Depot, something that would have been impossible just a few years ago before mycorrhizal additives started to go mainstream. 

The seed (5 lbs. that I bought online at seedranch.com for just $15) was easy to sow, though it required coverage from bird-proof netting. (Flocks of birds flew away as I approached the garden after my initial broadcast planting!)  The seed germinated right away and quickly dominated the plot. 

Then, in early October, I trimmed the grass with hedge clippers.  The cut grass should be no less than six inches high, Phillips says, for the best post-trimming root expansion.  Next spring is when I’ll take a mulching mower to the process. Then I plan to plant right into the plant-stubbled soil.  I’ll let you know what results.

Garden Experiment #2: Roasted Stinging Nettle Seeds

This idea comes from the far corners of the Web, where hairy counterculturists congregate.  (e.g.  https://www.youtube.com/watch?v=z7TJwh5nu9Y  and https://www.youtube.com/watch?v=rD4kDo0Z7Y4).   These videos drew me in because stinging nettle has become one of my favorite garden vegetables.  It’s great with garlic and eggs for breakfast and in evening meal main courses such as stinging nettle lasagna.  And, as permaculturists know, stinging nettle offers twice the nutritional value of even vitamin-and-mineral-rich mainstream vegetables such as spinach.  (I tell my permaculture classes that nettles have developed a sting for the same reason that banks install alarms: to protect valuables stored inside!  Fortunately, deer don’t wear gloves or know how to steam the leaves to neutralize the formic acid sting, so stinging nettle offers the added benefit of being herbivore-free!)

Stinging nettle seed is just as rich in nutrients as the leaves.  This year, with regular rains extending into July, my stinging nettle seed crop was exceptionally robust.  How much effort, I asked myself, would it take to collect the seed and was it worth the effort?

I was feeling pressed for time, so, as a test, I just cut the six longest stalks and dumped them top first into a refuse bag.  There they sat drying (until I remembered them!) for almost two months.  Then I cut off the little bunches of seed pods and pressed them into a colander.  Voila!  Tiny black seeds emerged on the other side.  We then roasted them with a little salt and oil.  The result: nutty and crunchy.

Critically, the roasted nettle seeds pass the all-important “wife test.” They added a nice crunchy texture to the rice and veggie lunch we prepared.  We thought, however, they might stand out best on simpler dishes such as scrambled eggs or plain rice.

In terms of future garden productivity, the newly-discovered edibility of stinging nettle seed extends the harvest season of what has become, for us, a staple crop.  The leaves are at their best from May through June, but become less digestible when plants start to flower in July.  (One of the visual pleasures of a breezy July day is to watch wind-borne clouds of nettle pollen drift past their neighbors.) Now we can harvest seed in quantity, roast it, and enjoy it during the winter months.

by Tom Gibson

Not to put too fine a point on it, but Mycorrhizal Planet, a new book by Michael Phillips, is a true breakthrough book, one that will provide new, valuable information for every serious organic gardener.  The book describes how mycorrhizal fungi work with plant partners and gives detailed, practical information on how to maximize the power of fungi in all sorts of gardens—from backyard tomato patches to full-fledged agroforests.

The book combines a distillation of extensive scientific literature with decades of the author’s hands-on experience growing fruit and other crops. [As chance would have it, I just completed an Ohio State mycology course  last fall and wrote my class paper on Maxmizing Positive Fungal Power in the Food Forest. So I know a little of the difficult scientific terrain Phillips had to traverse.]  You would expect such a book to be densely packed, and it is. But it is also logical, good-humored, and down-to-earth, which should be more than enough to lead the committed gardener down a productive path toward a new set of best practices.

We need them.

The 20^th Century produced some of the most brutal wars in history, but none so little noticed or comprehended as its War on Soil.  Some background and at least a partial explanation of why the War on Soil was so unwitting:

Soil, understood as something orders of magnitude different than mere dirt, consists of minerals, dead organic matter, and multiple living organisms that are often measured, breathtakingly, in billions per teaspoon.  Of these organisms, mycorrhizal fungi form the connective tissue on binds most plants.     Their hyphae—microscopic filaments—exude chemicals that dissolve potential food—from minerals to wood to dead insects—and then capture it by forming the equivalent of a new stomach wall around it.  See the graphic below where the red represents all the fungus’s external chemical activity. As its “stomach wall” expands, the fungus burrows its way tens of meters from its point of origin, all in the search for more food. 

Much of the food it seeks, however, is not for itself, but for its plant partners.  In return for the phosphorus, nitrogen and other elements our fungus gathers, it trades them in for plant sugars.  These provide the fungus energy to expand and capture still more plant nutrients. Put simply, mycorrhizal fungi extend the reach of plant roots by factors of 10 or more—costing the plant far less energy than if they had to expand their root system to cover the same territory.

Fungally-derived nutrients are so important to plants that they may devote one-third of all the sugars they produce to feeding fungi. It is no exaggeration to say that this trading system forms the core of life on earth.  It has been in place since both plants and fungi crawled their way out of prehistoric seas.   The relationship is so tight that mycorrhizae and plants have evolved to cooperate at the cellular level with the most prevalent mycorrhizal type—arbuscular mycorrhizae—actually penetrating the cell walls of a given plant root.   

But that’s only the beginning.  Individual fungi merge with other members of their own species to further increase their reach.  The resulting network forms microscopic highways for beneficial bacteria to travel the landscape. https://www.youtube.com/watch?v=AnsYh6511Ic And fungi emit a soil protein called glomalin which binds soil minerals and organic matter loosely together in a way that allows the overall soil complex to both breathe and retain water.  We call the resulting aggregation soil “tilth” —-the exact opposite of that gardening curse: soil compaction. 

Surprisingly, much of this knowledge has only emerged recently.  Glomalin, for example, was identified by a U.S. Dept. of Agriculture scientist in 1996!

It is this tightly-woven mineral/fungal/plant interrelationship that 20^th Century agriculture and horticulture ripped apart.  Tillage and plowing chopped up all those fungal hyphae.   Artificial fertilizers fooled plants into happily dropping their partnership with living food providers (sort of like satisfying children with a perpetual diet of macaroni and cheese!).  Disconnection from fungal partners, however, limited the availability of trace elements that fungi help scavenge.  These trace elements—molybdenum, boron, etc.–are essential to full plant health. Fungally-trapped soil carbon also disappeared.  All together, the negative cascade of disappearing nutrients left a void that growers filled with ever more fertilizers, pesticides and herbicides.  The ultimate result: ever less nutrition for both plants and their human consumers.

Phillips explains our downward agricultural slide in nuanced detail. But his greater emphasis is not on what went wrong, but how to make one’s own garden right. The three chapters (“Provisioning the Mycorrhizosphere,” “Fungal Accrual,” and “Practical Nondisturbance Techniques”) that make up the bulk of the book tell how to energize and expand fungal networks.

The committed gardener will find numerous possibilities for fungal enhancement of soil, ones that will require rereading and also rethinking of one’s approach to gardening.  Out of dozens and dozens ideas the book offers, here are a few that I’m either implementing now or plan to in the near future.

1. Ramial wood chips.  These are wood chips made from fresh twigs and branches, the ones where a tree’s most recent growth has occurred. As one might expect, such high growth portions of the tree carry the highest concentration of nutrients—calcium, phosphorus, nitrogen, etc.  Fortunately, these young branches are often the ones professional arborists insert into their chipping machines and which they often have to pay to dispose of as landfill.  So it’s easy to persuade neighborhood tree cutters to dump a truck load.  I’ve done that and the chips have made my soil darker and richer and my plants happier. 

   

2. Direct feeding of mycorrhizae by air-knifing holes in the soil under a tree’s drip line, then injecting (often proprietary) fungal food.  I had this done last fall to reinvigorate what my arborist diagnosed as oxygen-deprived oak trees.   The result: more vigorous-appearing oaks, but also a tripling (!) of fruit production of my pawpaw and peach trees planted under the oak’s drip line.
3. Planting of what Phillips calls “bridge trees.”  These are trees planted specifically to connect more of the separate fungal pathways of a given orchard or food forest and thus, as fungal networks tend to do, share nutrients to those plants which need them most.  Fruit trees typically work with arbuscular mycorrhizal partners, while oaks, maple and hickory work with ectomycorrhizal partners. Typically those two groups of fungi don’t “talk.” But a few tree species—willows, poplars, alders—partner happily bridge with both fungal communication gap. Within a broader landscape, they and their fungal partners open the possibility of tapping a much wider nutrient pool.  So I’ve begun to encourage alders—already self-seeding to some extent in my food forest—by planting more in strategic locations.

As readers can now gather, Phillips goes into considerable detail.  Yet what makes the appearance of this book especially exciting is how readable  the author is able to make it.

A typical passage will begin close to the “duh” level of simplicity; e.g. “Mycorrhizal fungi are the principal means plants have for obtaining phosphorus…the middle letter in NPK as represented by those three omnipresent numbers on a bag of fertilizer.”  But then Phillips escalates quickly into a discussion of slow- vs. fast-release phosphorus and the relative “cost” to the plant of exuding organic acids to feed phosphorous-gathering fungi.  Similarly, when Phillips must dip into scientific language—like “anastomosis,” the merging of separate fungi—he always defines it in understandable terms.

So, readable, yes, but also dense and complex.

Did I mention that this book is for gardening nerds?