Hilo people- tell me about the forest floor where your palms grow

[trioderob]

I have been digging in and learning about soil microbiology.

this info has come from several sources including farming practices of the mid west.

a few questions for the folks in Hilo:

1) how deep is the layer natural mulch in your garden ?

2) how deep is your black topsoil ?

3) do you notice an abundance of mushroom and fungii ?

4) is your gardens natural mulch typically moist year round and after a rain does it ever dry out ?

5) is there an abundance of small animal and insect life ?

6) if you were to use a hand shovel to dig a small hole about 3 foot deep what would the cross section look like ?

7) what grows in the areas left wild - in other words bushes ? weeds ? thick grasses ?

if you can - tell me which of these soil profile match your garden:

http://www.ctahr.hawaii.edu/oc/freepubs/pdf/soils_poster_3.pdf

Edited January 9, 2014 by trioderob

[Kim]

Soil is mystery to me, for the most part. Did you see LilikoilLee's photo of a cross-section of earth in her area of Kona? Search for it, a great photo.

I will try to answer your questions as best I can. Maybe you can teach me something about soil microbiology. Volcanic islands will differ from farms in the mid-west of course.

1) Natural mulch -- in the cultivated areas of my garden, the only mulch is what I have added (wood chips). Off in the rough I could only guess, for the reason that it is truly quite rough -- downed logs, dense brush, tangled vines. Best guess, not more than 2 inches because everything decomposes very rapidly in the wet and warm conditions.

2) Topsoil -- where I most recently did some hand clearing and planting, there is no more than 2 or 3 inches of soil before hitting rock.

3) Lots of mushrooms and fungi on the downed logs, but not sure I have ever seen any directly on the ground.

4) Again, I have to distinguish between garden and untouched forest. The wood chip mulch I put down may dry on the surface, but retain moisture underneath. In the untouched forest, everything is always very wet.

5) Small animals include birds, mongooses, rats, various lizards and gekkos, coqui frogs, etc. Pigs probably don't qualify as small. Insects -- different kinds of ants, centipedes, millipedes, earthworms of unknown names, really big moths, sometimes grasshoppers, praying mantis, and many unseen beetles.

6) it would be difficult to impossible to dig a hole 3 foot deep with a hand shovel due to the lava rock. But you might find a lava tree hole 3 or more feet deep. What you see as you begin to dig is a little soil and a lot of volcanic rock. When you see where pigs have dug, you see lots of mud on top the rock. It's amazing. And the dug soil is very dense and stinky.

7) Areas that have been cleared then let go will be filled with 30-ft. soft wood trees in less than 2 years, as well as high, dense woody brush and invasives such as tibouchina, strawberry guava, miconia, maile pilau vines, thorny mimosa (sensitive plant), elephant grass, and Archontophoenix alexandrae and Albizia trees. Natural uncleared areas grow ohi'a trees (Metrosideros polymorpha), plus all those previously mentioned, and Monstera vines, Allamanda vines, and Spathodea campanulata, various gingers, whatever has escaped the cultivated gardens. Edit: In sunny spots will be masses of flowering annual weeds that release puff-balls of seeds into the breeze when disturbed.

Edit2: I forgot to mention the wild terrestrial orchids that grow in the natural forest -- Phaius tancarvilleae.

[trioderob]

Kim-

thanks for taking the time to reply to my post.

I want to see if there are any more reply s then i will give some microbiology feedback.

some of the scientific types here can add feedback also as they wish.

[Gonzer]

Great topic. Might explain why rain forests are basically green deserts.

[mike in kurtistown]

I'll give it a try. My lot is about 5 or 6 miles from Hilo in former sugar cane land. The flatter part of it was used for sugar cane and the very uneven and hilly part was used as a quarry for a cane road and as a place to put rocks and soil from clearing and grading of the sugar cane area. So none of it is natural. I think that most of the natural soils in the coastal lowlands (I am at 700-800 feet) disappeared early during the Polynesian settlement (1200 AD and later). Full exploitation of arable areas by the Polynesian settlers was followed 100-200 years ago by overexploitation by the sugar cane industry.

1) Natural mulch? Flat areas that have not been maintained have heavy growth of big grasses or uluhe ferns that have dead older growth beneath the green growth. I prefer to keep the flat areas mowed. Mulch created by moving decomposes very quickly and is used by the grasses.

2) Topsoil? In the sugar cane area, decades (centuries?) of plowing has left a mixture of very rich brown soil and broken up volcanic rock. The depth varies. There are outcrops of massive rock, and a few areas where rock shelves a few inches below the surface prevent making palm holes. But in most places, the rock/soil mixture is at least a foot deep and grades into something like cinder at greater depth. When my septic tank was installed, they ran into massive rock at a depth of about six feet.

3) Not many fungi in the flat, grassy areas. I sometimes get fungal blooms in my pots that don't seem to affect the seedlings.

4) The dead stuff under the grass will usually be wet, as it rarely stops raining for very long here.

5) When I moved here from rural Florida, I was stunned by the relative absence of small life. There are small slugs, big snails, centipedes, and occasional legless lizard, a very few butterflies, and several ant species. Hawaii originally had no ant species, but surveys in recent years have shown over 40 exotic species. The species mix on my lot has changed appreciably as I have cleared it. Small geckos mainly in the house. Mongooses that I often see and rats that I rarely see. I have fenced out the pigs. Pigs feed mainly on earthworms, which are abundant in the soil and manage to get in pots on elevated platforms.

6) I couldn't dig a 3-foot hole with a small shovel because I would encounter rocks that would have to be removed by a larger tool. I have noted that the fertile soil grades into something more like cinder starting about a foot down. The percentage and depth of soil is greater in some lower areas where it is augmented by erosion from higher areas.

7) Massive dense grasses and trash trees (albizia, gunpowder trees (Trema orientalis), melochia, strawberry guava. Surprisingly, uluhe fern areas seem to maintain themselves, perhaps because the mass of underlying dead fern leaves inhibits seedling growth. The worst invading trees that just come up everywhere if not controlled are Trema, melochia, and albizia, in that order. Cecropia is less common. I rarely find that strawberry guava (waiawi) coming up in areas away from other plants, but it forms massive clumps where it aleady exists. I suspect that my clumps were deliberately plan ted to stabilize hillsides. I don't worry about Miconia (it's here but doesn't proliferate much), but a small scrubby relative called clidemia is a bloody nuisance and spreads everywhere. Kim mentioned maile pilau and sensitive mimosa - they are a nuisance here, too. I have had to remove humungous growths of Alamanda, and now I spray it whenever I see it. Oh, and I do have ohia trees that have colonized my spoil pile areas. I protect them, some 50 feet tall, but they are natural colonizers and are in no way part of the original ecosystem. What the natural ecosystem might have been I have no idea.

I apologize for the lengthy response, but it has given me the opportunity to run on about my clearing and maintenance problems without going out and actually doing more work.

[trioderob]

I will wait for other reply's but will interject a tidbit so the thread does not get boring.

from my studies it appears the large grass cover seems to be highly important.

I am talking about something along the lines of winter rye.

biological activity is dramatically increased in the area surrounding roots.

rye and other large grass such as sudan grass create an extremely extensive and complex root system.

these systems in the first 18" of soil depth control the general fertility of your garden

[trioderob]

one goal is to fracture but not till the soil.

tilling has many negatives including bring weed seeds to the surface and creating a microbial bloom

which peaks and then crashes.

large grass fractures the subsoil permitting roots to spread, oxygen and water to penetrate and a stable soil micro fauna to develope

[trioderob]

here is a little background of what I am digging into

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&ved=0CFsQFjAH&url=http%3A%2F%2Fanrcatalog.ucdavis.edu%2Fpdf%2F7249.pdf&ei=Lx_PUoWcDMzloASqw4HIAg&usg=AFQjCNETRhxXIgPcVH1pXWNIbg-sdfXPsw&bvm=bv.59186614,d.cGU&cad=rja

the part I am after is the importance of low N material turned into humus by way of fungi vs high N organic and man made fertilizer which causes a huge microbial explosion followed by crash

Edited January 9, 2014 by trioderob

[DoomsDave]

Hawaiians, thanks for your long replies!

Fascinating.

A glimpse into another world I missed when I was there.

Take all the time and space you need . . . .

[trioderob]

so while adding wood chips and other manner of compost and mulch is important my research is

leading me to believe that what you GROW for cover is actually more important than what you place on top.

Grasses usually provide the greatest amount of biomass both
below and above ground and will build soil organic matter most quickly. Summer grasses such
as sorghum-sudangrass and millets are good choices for early summer plantings while the more
familiar annual ryegrass and cereal grains can be planted mid- to late-summer. Legumes will fix
atmospheric nitrogen that can be used by next year’s cash crop. Cowpeas are an excellent choice
for mid-summer plantings, while hairy vetch, crimson clover, and winter peas can be planted
through late summer. Be sure to inoculate all legume seed. Brassicas such as oilseed radish,
turnip, rapeseed and canola have tap roots that help break up tillage pans and improve
permeability while being an excellent nitrogen scavenger and can be planted mid- to latesummer

water:

well its no surprise that Hilo gets alot of rain - but the second benefit is that it keeps all the nice soil fauna alive.

i was surprised to find out just how much humidity is really needed to keep it from being killed off.

about 65% moisture is needed .

Edited January 9, 2014 by trioderob

[mike in kurtistown]

An additional note about the small grasses in the areas that I keep mowed. The roots are very dense and bind the top inch or so of soil so tightly that I throw away the sod pieces when digging palm holes without trying to free the soil from the roots. Ironically, the bases of the monster grasses, when cut back, turn out to be relatively far apart, the roots apparently tapping deeper parts of the soil. I do recover most of the soil from them.

[trioderob]

those dense roots are home to a wide array of soil life - with large grasses the total length of root produced is astronomical.

away from those roots the soil life declines tremendously

this is due to the roots fluffing off fresh carbon with is used as a building block by the bacteria.

the areas of earth with the best soil such as the Ukraine have had millennium of large grass fields live and die.

its nice to have something on the surface but logic and empirical evidence show that deep roots are even better as they provide path ways thru the soil and prevent it from becoming lousy hard pan

what i would like to create is a balance whereby I also have healthy soil fungi which take over as the soil bacteria are unable to process the organic matter any further.

this seems to be the key to producing humus which has a buffering effect on the garden.

I was interested to find out if Hilo soil is rich in CELLULOSE eating fungi - not just bacteria.

the first having a more permanent improvement on the soil

Soil fungi can be grouped into three general functional groups based on how they get their energy. Decomposers – saprophytic fungi – convert dead organic material into fungal biomass, carbon dioxide (CO2), and small molecules, such as organic acids. These fungi generally use complex substrates, such as the cellulose and lignin, in wood, and are essential in decomposing the carbon ring structures in some pollutants. A few fungi are called “sugar fungi” because they use the same simple substrates as do many bacteria. Like bacteria, fungi are important for immobilizing, or retaining, nutrients in the soil. In addition, many of the secondary metabolites of fungi are organic acids, so they help increase the accumulation of humic-acid rich organic matter that is resistant to degradation and may stay in the soil for hundreds of years.

Edited January 10, 2014 by trioderob

[Justin]

I was reading the other day that legumes don't provide the same benefit to the same Hawaiian native plants as they do to most, likely because the Hawaiian native plants have adapted to dealing with less nitrogen, and don't want/need what the legumes provide in terms of nitrogen fixing. Sort of similar to how Proteaceae can easily be killed by phosphorus-based fertilizers, because they've adapted to their surroundings and the minute amounts of phosphorus in the native soil.

[trioderob]

the legumes produce nitrogen by way of bacteria nodules on their roots.

in spring these plants become N users - not creators - because the decomposition on debris on the forest / field ground goes thru a bloom as the bacteria reach a temp which promotes subdivision.and actively.

in fall when the soil bacteria is dormant this reverses and the imprisoned bacteria in the root nodules provide the N to grow the field peas/vetch .......

notice how the roots grows out and traps the bacterium thru an "infection thread"

Edited January 10, 2014 by trioderob

[bgl]

Rob,

Not to be picky but I'm wondering if by "Hilo people" you mean people strictly in Hilo or people on the Hilo side of the Big Island? I read it to mean "people on the Hilo side" so please correct me if that's incorrect. Kim and Mike have both given excellent and extensive answers based on my second definition. And, again if this is what you mean, it's a bit like asking "San Diego people - tell me about etc." referring to everybody in San Diego County. So, do you mean Point Loma or Borrego Springs? Mira Mesa or Fallbrook? Same thing here. North of Hilo (Hamakua coast), deep soil and very different conditions compared to the Puna district, south of Hilo. Not to mention the various elevations, from sea level and several thousand feet up with VERY different rainfall and wind conditions. And even within the various subdivisions in Puna there can be vast differences. In my old garden there was hardly any soil to speak of. Maybe 2-3 inches in most areas. In my new garden, only just over a mile away, I have much more soil. In some cases 10 inches down, which is a LOT in this area. And as already has been explained - digging a 3 ft hole in Puna is not even remotely something you might consider unless you bring in heavy machinery or a jackhammer. Typically you hit bluerock about one foot down or less. And when you hit bluerock and you're digging manually, you have one choice and one choice only: give up.

Bo-Göran

[trioderob]

taken to its extreme you find that very few things can break down wood.

nature made it that way on purpose.

to break down wood chips , branches etc you need fungi to take over and release a chemical called "CELLULASE"

not easy stuff to find - except in the stomach of a termite or under favorable conditions in the soil.

most fungi can not kill living trees except for a few species luckily nature has given us FUNGIVORES to keep them in check.

Bo-

anyone on the wet side can chime in. I was on the big island before getting into palms to see the eclipse years ago.

i recall the west side being pretty dry and the north of Kona being very forest like.

GO- CHARGERS !

Edited January 10, 2014 by trioderob

[bgl]

Right, I assumed you meant the "wet side", a/k/a the Hilo side or the east side or the windward side. Which is a large area with vastly different environments and weather conditions and also soil conditions. The west side (Kona side or leeward side of the island) is definitely drier but also has many many different environments.

[LilikoiLee]

Aloha from the Kona side of the island.

Kim mentioned this photo so I dug it out to repost. This was taken on the dry Kona side of the island but with the exception of the moisture content, Kim pretty well defined the nature of the soil and immediate underlying rock that we all share on the island. Individual lava flows are older or newer, softer or harder (locally referred to as bluerock)but the bottom line is that the entire island is so young geologically that there's not an awful lot of soil in most places. A few inches down and there's the rock. Even the material on top of the rock is hard to always describe as 'soil'. It's more an aggregate of loose rock, light soil, twigs, moss, etc. On a rare occasion we find a pocket of mostly soil that may have a depth of two feet.

Lee

[Dr. George]

Thought the attached from the University of Hawaii might be of interest, particularly the distribution maps. - gmp

Soils of HI.pdf

[trioderob]

thanks Dr G.

looking at this information it is clear the surface soil profile is very complex.

complexity is the key.

it makes for a complete and balanced system which does not spike and crash.

large quantities of microanthropods shread the organic material and allow the bacterium to have more surface area on which to apply their digestive juices.

nematode eat large quantities of protozoa and are held in check by carnivorous fungi

earthworms eat the very protozoa which live in the decaying matter - they leave tunnels which are coated with polysaccarides

this is then fuel for more bacterium

because it never stops raining there is always root actively - this provides fresh carbon to the soil

because of the moisture - humus is produced by the fungi instead of having a rapid bacterial bloom which only releases gases into the atmosphere.

come on Rivers lets get the Broncos !

.

Edited January 10, 2014 by trioderob

[trioderob]

now whats trippy is that the growth of Mycorrhizal fungi allow the plant to save water.

here is how.

the palm roots need to expel water to attract certain minerals it needs.

one of the things its needs is carbon.

the fungi on the other hand dont need much carbon - they need food.

so the two form a team and the fungi feeds the plant carbon - the palm feeds the fungi food.

the fungi has a delicate body structure so if you disturb it - you kill it and put the system out of balance

does anyone find this interesting or should i stop ?

Edited January 10, 2014 by trioderob

[trioderob]

one other issue is that the soil may have aggregate nodules.

so in other words the path the water vapor must take to leave the soil surface and evaporate is not a clear path but a labyrinth.

its like how a straw with a million twists and turns would be much harder to draw on then a normal straight one.

this helps to retain moisture in the soil once again feeding the fungi

Edited January 10, 2014 by trioderob

[mike in kurtistown]

Rob,

The soil science is interesting, keep it up if you wish, but I'm too much of layman in this area to grasp all of it. And Bo's point about regional, even local variability, is quite pertinent. Hawaii is a place where one can live in one of the rainiest spots in the USA and drive for half an hour and be in a desert. Or I can drive up the Volcano Highway to Mountain View or Glenwood (15-20 minutes) and be in a soil area with 10-15 feet of rich soil with little or no rock content. Or to Bo's old garden (20 minutes) where there is no soil at all.

Go get em, whoever!

[trioderob]

Here is another area which requires the deepest of thought:

bottom line is that the stable humus layer allows the proper ionic flow

also note that then the soil is too acidic nasty metallic elements such as aluminum become available to the plant

that's a bad thing - that's not a good thing

Cations

What CEC actually measures is the soil's ability to hold cations by electrical attraction. Cations are positively charged elements, the positive charge indicated by a + sign after the element symbol. The number of + signs indicates the amount of charge the element possesses.

The five most abundant exchangeable cations in the soil are calcium (Ca⁺⁺ ), magnesium (Mg⁺⁺), potassium (K⁺), sodium (Na⁺) and aluminium (Al⁺⁺⁺).

Cations are held by negatively charged particles of clay and humus called colloids. Colloids consist of thin, flat plates, and for their size have a comparatively large surface area. For this reason they are capable of holding enormous quantities of cations. They act as a storehouse of nutrients for plant roots.

As plant roots take up cations, other cations in the soil water replace them on the colloid.

If there is a concentration of one particular cation in the soil water, those cations will force other cations off the colloid and take their place.

The stronger the colloid's negative charge, the greater its capacity to hold and exchange cations, hence the term cation exchange capacity (CEC).

CEC measurement

Concentrations of cations are expressed in centimoles of positive charge per kilogram of soil (cmol(+)/kg). This measurement is equivalent to the previously used unit me/100 g.

Adding the concentrations of each cation gives you an estimate of the CEC figure. A figure above 10 cmol(+)/kg is preferred for plant production. Soils with high levels of swelling clay and organic matter can have a CEC of 30 cmol(+)/kg or more.

A diagrammatic representation of the flat plate-like structure of a colloid. Its negative charges are along the edges of the plates. The cations are attached to the colloid by electrical attraction between the positive and negative charges.

The five exchangeable cations are also shown in soil test results as percentages of CEC. The desirable ranges for them are: calcium 65–80% of CEC, magnesium 10–15%, potassium 1–5%, sodium 0–1% and aluminium 0%.

pH and CEC

Soil pH is important for CEC because as pH increases (becomes less acid), the number of negative charges on the colloids increase, thereby increasing CEC.

CEC levels Humus

CEC varies according to the type of soil. Humus, the end product of decomposed organic matter, has the highest CEC value because organic matter colloids have large quantities of negative charges. Humus has a CEC two to five times greater than montmorillonite clay and up to 30 times greater than kaolinite clay, so is very important in improving soil fertility.

Clay

Clay has a great capacity to attract and hold cations because of its chemical structure. However, CEC varies according to the type of clay. It is highest in montmorillonite clay, found in chocolate soils and black puggy alluvials. It is lowest in heavily weathered kaolinite clay, found in krasnozem soils, and slightly higher in the less weathered illite clay. Low CEC values can be improved by adding organic matter.

Sand

Sand has no capacity to exchange cations because it has no electrical charge. This means sandy soils such as podzolic topsoils have very low CEC, but this can be improved by adding organic matter.

Aluminium and sodium

Aluminium (Al⁺⁺⁺) and sodium (Na⁺⁺) cations are not plant nutrients, so are not wanted by the plant. Aluminium is not present as a cation when soil pH _(CaCl2) is over 5 because it is precipitated out of the soil solution. It is only at pH _(CaCl2) levels below 5 that it may become available as a cation, and under 4.5 may become available in toxic levels, displacing other cations from the clay or humus colloids. This is one reason why it is important to maintain pH levels at 5.0 or more.

When exchangeable sodium is present in quantities greater than about 5% of the CEC, it makes the clay particles unstable in rainwater. This shows up as dispersion or cloudiness in water. Dispersive soils have poor water entry and drainage and set hard on drying.

Edited January 10, 2014 by trioderob

[trioderob]

someone tell me about that primo glenwood location

[trioderob]

in a ideal system like Hilo the weight of the various bugs, micro insects, bacterium, amoeba, nematode,

fungi etc can be up to 6X that of a poor soil profile.

600% more

all those little buggers are making alot of food for the palms and in a real good form that they can use.

I AM OUTTA HERE.

[mike in kurtistown]

Glenwood is at about 2,000 feet, and several degrees cooler than where I am. Contrary to expectations, it is not a perfect place for growing everything. A cycad grower located up there, or maybe in somewhat lower Mountain View, and found that cycads rotted if planted in the heavy, wet, clayey volcanic soil. So he has to grow his cycads in mounds of cinder. Possibly, some palms would find the wet, clayey soil too much, also. I grow many cycads on well-drained hillsides where the "soil" is at least 50% broken rock, and they seem happy. Don Hemmes planted the Pana'ewa Zoo cycad display in piles of cinder (with major contributions from the Mountain View grower mentioned above).

[trioderob]

anything "too much" is horrible for plant growth

too hot they dont grow

too cold they dont grow

too acid they dont grow

too alkaline they dont grow

too wet they dont grow

too dry they dont grow

in the case above the soil is so wet that is does not allow for the exchange of gases

the wonderful little animals i have talked about breath oxygen like us.

if they cant expel that CO2 they produce they cant grow and their numbers plummet to a balance point

Edited January 11, 2014 by trioderob