Jonathan A Young

Thanks for the ideas, everyone.  If we get a dry stretch this summer I may in fact water half a row to keep the surface layer moist, and not water the other half of the row.  I don't think that well-established, deep rooted veggies would wilt after a month of no rain in my soil.  But not wilting isn't enough; I want tons of vegetables, which is why I am curious about the necessity of moisture in surface layers.  I only plant 10 or 12 tomatoes and give each plant tons of space and lots of love.   I could probably get more production by planting 10 times as many plants in the same space, but I get my kicks out of monster plants loaded with tomatoes.  

This determinant variety grew 5-1/2 feet tall and produced 80+ pounds last year.  I wish I had taken a photo of the whole plant!




As for the fungus comment.... yes.  My soil looks a lot like the soil in the hardwood forest on my property.  It is a giant fungal mass of organic carbon and worm castings.

I have invested an inordinate (and totally inefficient) amount of time building feet deep of soil.  It's not a practical approach, but it's been an interesting years-long experiment that should pay dividends for the rest of my life.  

 

Over the past number of years, I have added hundreds of cubic yards of wood chips to my large garden, along with a few hundred yards of composted leaves and grass clipping.  (I live in the forest, and I have lots of arborist friends who bring me chips year round.)   I compost some of the wood chips for a few years before adding them to my garden, and I have added a ton fresh to the garden by piling them feet deep between wide raised rows, and letting them compost in the garden.  After the chips are between the rows for two or three years (while being top dressed with grass clippings throughout the summer), I dig them out and add them to the raised rows.  After two or three years, the wood chips between the rows have turned into something that looks like coco fiber, and the only discernible pieces of wood are the texture of styrofoam.  By following this process over and over, my 48" wide raised rows keep getting higher, and the chip area between the rows keeps getting deeper and deeper.  

My raised rows are now 4+ feet deep of soil, well composted wood chips, and fully composted leaves and grass clipping.  I can dig up to my shoulder with just my hand, I have an almost disgusting population of worms, and I've grown some monster vegetables.    

Although summer precipitation here varies widely from year to year, the soil is always saturated in the spring due to the winter melt and spring rain.  My entire garden is above grade and I installed drain tile around the edges, so although it gets very wet 2+ feet deep, it doesn't tend to go anaerobic.  It's just deep, wet, and has an extremely high organic matter content.  The organic matter combined with the native clay makes my soil an incredible sponge. (The entire garden is built on top of a bunch of buried logs and tree stumps, so the water holding capacity is limitless for practical purposes.)  We had a very dry summer last year and reached what was called a stage 3 drought ("exceptionally dry").  I barely had a blade of green grass in the yard, but my garden never really dried out more than about one foot underground, even in areas that I did not water.  

Vegetables develop enormous root systems in the extremely loose and fertile soil that I have built up.  Okra and tomatoes put out roots at least 10-12 feet from the stalk and 4+ feet deep. Nevertheless, the upper 12 inches of soil seem to contain most of the roots, with far fewer reaching down below that.

Amidst the drought last year I was torn about whether I should water.  On the one hand, there was plenty of water and nutrients available deep underground, and once well established, my plants had access to that water and nutrients.  On the other hand, most of the roots were in the upper layer of soil, so if I let that layer dry out, those roots would be unable to absorb water and nutrients.   I am fairly certain that if I had never watered once last year, my well established plants with deep roots (tomatoes, okra, eggplant, corn, peppers, etc) would never have wilted from drought.  But on the other hand, I worried that the plants would not produce well if they were forced to rely only on their deep roots.  So I did give them a deep watering once a week throughout the drought.

Does anyone have any insight or experience about whether allowing well-established plants to go deep for water and nutrients will affect yield?  Any other pros/cons to watering the surface roots when water and nutrients are available deeper?

My experience is that fungal dominated compost works best on my property for the plants that I grow.  Hands down.  

The best compost I have made?  Lay down 2 feet of wood chips, top dress with fresh grass / clover clippings once a month or so.  Don't touch the wood chips.  Wait two years.  Don't touch the wood chips.  Plant into the wood chips.  You will be planting into a thick web of fungus that will dominate the nearly-decomposed chips and make your plants very, very happy.  

My experience is consistent with professor David Johnson's research on fungal-dominated compost.  

And finally, since we're on the topic of unconventional growing media... zucchini and yellow straightneck squash growing in 12-18" deep ramial wood chips, laid down 2 years ago when planting austree willlow cuttings for a quick privacy screen.   Photos are from 3 weeks after planting seedlings I started indoors. The willows are now 20-25 feet tall, and the wood chips are about 75% composted.  They are black, spongy, and clumped together by all the fungus that is going to town on them.   I've top dressed the chips with clover and tall fescue clippings every month or two for the past two years, which seems to have really made the fungus happy.  

I started with 2+ feet of chips, and they have shrunk down a lot.  I put at least 100 yards of ramial chips around 30 or so willows back when I was getting 2 or 3 truck loads a day for many months.  

The results have been incredible with regard to the willows, and now I've managed to sneak some squash in there as well.  Part of my squash vine borer control strategy this year is to scatter squash around 5 acres to see if those little bastards manage to find them all.  THey are also easier to spray with Bt when they are out in the open like this.

Tomato growing in amended native soil... Half the size of the ones in compost.

Photos of vegetables growing in compost.   When I say growing in compost, I don't mean I top dressed or mulched with compost.  Nearly 100% of these plants' roots are currently in compost.  

All were planted from seedlings on May 21 in SE Michigan.  Modest amount of 3-5-5 slow release organic fertilizer mixed in planting holes and top dressed some bone meal a little while later.  

Tomatoes are indeterminate yellow cherry type.  They are already 2-1/2' tall, and loaded with flowers.  

Squash are acorn.  Incredible growth from these in less than a month growing in nothing but compost.  

Peppers doing great also in 2 feet deep of compost on top of amended native soil.  

Jay Angler wrote:@ Jonathan A Young - Interesting that you just experimented with adding a little clay, as I did the same thing this spring to some raised beds I made and essentially for the same reason. It's a bit early to tell the long term effect, but at the moment the beds are growing happily.

I agree that not all compost is created equal, particularly if it's made of a limited variety of material. I don't particularly aim for a really hot compost as then it seems as if all the carbon and nitrogen I want to keep are going up into the atmosphere. I've been trying to mix in what biochar I can make to help out the microbes also.

I, too, have noticed the difference in compost quality when hot composting vs. not-so-hot composting.   I have a 2 acre yard surrounded by an oak-hickory forest, so you can imagine the amount of fall leaves that I get.  When I hot compost them, they turn into extremely fine, crumbly black compost.  Nice stuff, but....  when I cold compost them, they retain a little more texture and plants seem to prefer this.

I am about to harvest the largest heads of garlic I have ever grown.  What I did differently this time is, after I planted the cloves in the fall, I mounted 8-10" of shredded oak leaves on the top and sides of the row, and topped that with an inch or so of white clover clippings.  The garlic had no problem poking through all of this, even as the rain matted the leaves down a bit.  By the spring, the leaf / clover layer was only about 1" thick, and it looked like something between leaf mold and cold compost.   This area is absolutely loaded with garlic roots.  The garlic has grown more vigorously than when I have mulched / side dressed it with fully broken down hot compost. There is something about the decomposed-but-not-disintegrated texture that vegetables seem to love.  

I think it comes down to fungi and mesophilic bacteria making more nutritious compost than the thermophilic bacteria.  I'm not the first to make that point, but my experience is very much consistent with what others have said on the subject.  

@ Michael Helmersson

I am a recovering lawyer.  We are not known for brevity.  

Hi, Chuck, I registered for the forum (been lurking for many, many years) just to respond to your question.  I made numerous Hugel beds a few months ago, and the top 6 inches or so are compost made primarily of arborist (ramial) wood chips, grass and white clover clippings, fall leaves (mostly oak), and egg shells.  This compost was created in about a year in a very large pile, built and turned with a compost tractor.  After 1 year, everything was fully decomposed except some wood chips which are soft and spongy but still discernible as wood chips.  

Under the generous layer of compost in my Hugel beds is a thick layer of white clover clippings and tall fescue hay, followed by partially decomposed forest wood.  The bottom of the Hugel beds are 3-5 feet thick chunks of willow and poplar wood.  

I planted tomatoes and bell peppers in one Hugel bed.  As an experiment, I also planted tomatoes and bell peppers in one of my normal garden "mounds", which are basically 12" unframed raised beds of heavily amended clay soil.  I've only had 3 years to pump organic matter into the native clay, but I have added at least a few hundred yards of grass clippings, 20-30 yards of shredded oak leaves, a disgustingly large amount of pond scum and algae, many yards of soy bean straw, thick arborist wood chip paths, kitchen scraps, etc... I consider my normal garden soil to be adequate, but not great, at this point.  

I tell you all of this so you can understand the following comparison:

The tomatoes that I planted on the Hugel bed, growing in nothing but compost, at this point, are twice as large as those planted in the regular garden soil.  The peppers are about the same, although the ones in the Hugel bed look healthier and more vigorous.  Both plants received a small dose of slow release organic fertilizer at the tine of planting, and both were top dressed with some bone meal about 2 weeks after transplanting.  

So can you grow plants directly in compost?  After one month of doing so, my answer is absolutely yes.  But...

Point 1: My compost does not hold water as well as I had hoped.  

My compost is free draining, similar to sandy loam.   (This is due, in part, to the nature of the Hugel bed, since the water has a place to drain.)   The compost holds moisture better than very sandy soil, but not nearly as well as my amended clay soil.  For the first few weeks I watered the tomatoes and peppers planted on the Hugel bed almost every day since the compost would be pretty dry down about 2 inches unless it had rained.  As the plants and their roots have grown, I have watered less.  In comparison, I have yet to water my tomatoes and peppers planted in amended clay soil.  I plan to mulch the Hugel beds with a thin layer of clover clippings and some partially decomposed wood chips.  That should help some.

Point 2:  Compost is not always nutrient rich.

Compost is always good for improving soil tilth, but it is not always as nutrient rich as many believe.  This seems to depend, in large part, on what went into the compost.  Grass clippings have a lot of nutrients if you have enough of them, but they do not seem to add much in terms of texture / tilth.    Wood chip compost is not great in terms of nutrients, but it has a wonderful texture / tilth.  Decomposed fall leaves are the best of both words in my opinion -- decent mineral content and great texture.  So far, my compost + a little fertilizer / bone meal is plenty nutritious, but I am curious to see if the compost has sufficient nutrients once the plants get big and start producing heavily.  

Point 3:  Consider mixing a little clay in with your compost.  

After spending years battling heavy clay native soil, I recently found myself actually adding a little bit of pure clay subsoil to one of my new Hugel beds to help with water retention.  I built a camp fire over some huge chunks of pure clay subsoil.  The heat makes the clay very crumbly once it cools.  I took this crumbly clay and mixed it with compost at a ratio of about 90% compost 10% clay.  The result seems extremely promising.   The clay adds a little more "body" to the compost and definitely helps it hold onto water.  But at only around 10% clay, there is no compaction and no stickiness.  This compost / clay mixture is still free draining, but remains moist a day after watering, unlike the pure compost.  And the clay should help retain nutrients, as well as being a rich source of minerals in its own right.  

That's all I've got. I'll try to take some photos later today of the tomato plants grown in compost vs. amended clay so you can see the dramatic difference.