Increasing Soil Fertility and Health through Cover Crops, for a forest garden

Dear Permies,

My goal is to slowly incorporate a poly-culture food forest for personal use on my property (2 acres) in Puna Hawaii without the use of fertilizer, pesticides or other external inputs, besides seeds and plants.

The elevation is 400-500 ft. There is plenty of rainfall, however there is little soil due to the lava that covers the ground. Even so the conditions are such that the property is a Jungle of invasive species.

My intention is to use a backhoe with hammer and loosen (for root growth) up 6x6 areas spaced 20-25 feet apart for the larger trees. Then scrape the soil and organic matter from the surrounding area on top of the planting area. Then plant the following green manure to build soil fertility. After that periodically chop and drop until the soil conditions are optimum.

http://www.ctahr.hawaii.edu/oc/freepubs/pdf/GreenManureCrops/sunnhemp.pdf

http://www2.ctahr.hawaii.edu/oc/freepubs/pdf/GreenManureCrops/whitesweetclover.pdf

http://www.ctahr.hawaii.edu/oc/freepubs/pdf/GreenManureCrops/pigeonpea.pdf

http://www.ctahr.hawaii.edu/oc/freepubs/pdf/GreenManureCrops/lablab.pdf

This is very much an experimental project, just out of plain curiosity and desire to have my own organic fruits and nuts if successful. There is no time pressure, so I am open to spending several years building soil fertility before actually planting the trees.

I have little experiance with food forests, therefore I am soliciting advise from like minded people with experiance to increase my chances of success.

Your advise, suggestions and thoughts are gratefully appreciated. If you require more information please do not hesitate to ask.

Mahalo,
Ajit

I'm a Florida Master Gardener and have read a bit on dealing with rock... we have similar thin soil conditions down in parts of Homestead. Down there it's all limerock and what the extensions recommend is that you use a pickaxe or other implement to punch holes in the rock, then fill with soil. Perhaps that would be impossible with igneous rock! Maybe dynamite?

I suppose you could also plant as many biomass producers as possible and then just keep dumping materials on the ground to thicken up your growing area. The climate is certainly amenable to massive amounts of growth. Perhaps lots of vining plants, too, as traps for nutrients.

What invasives are you currently dealing with? Anything you can harness?

Aloha Vidad,

I have heard multiple suggestions, dynamite, jackhammer, backhoe, rip with D9 bulldozer, plant in existing cracks, build mounds of soils etc. Backhoe with Jackhammer is the most appealing, since I do have some lovely native speices which I want to preserve.

As for the invasive species I am dealing with Stink Maile, which smothers the host, and strawberry guava, which is difficult to get rid of and grows everywhere. Some people use a wood chipper to shred the strawberry guava for biomass, something I am considering as well.

I am hoping to work with Mother Nature and create islands of growing spaces and help to nurture the fruit trees. Hopefully they can eventually over shadow the other guys.

I figured if the indigenous people of the world were able to grow food naturally for thousands of years us food forest people are not so crazy after all.

Your "stink maile" sounds a lot like our bindweed. It crawls all over plants and cuts off the light.

As for the strawberry guavas, I know they're invasive - but they're also a delicious edible. Are you not getting fruit from them? I think if I had a problem like that, I'd be happy. My advice on those is to just leave them if they're productive and cut down the ones that are really in the way. I think you're right - if you get some overstory plants going, they'll cut down the light eventually and I imagine that would lower germination and competition. Here I'm trying to grow them without too much luck yet - it's too cold! I wish they were invasive, darn it.

I tend to take a pretty lax view of invasive plants. If they're in the way or really, really bad... I knock them down. But if they have uses, I let them live. For example, we have "mimosa trees" here (Albizia Julibrissen) and we're told to KILL KILL KILL them. However, they're a good nitrogen fixer and our sand really needs that... so I grow them next to my fruit trees and plant to chop and drop them as mulch if needed. Another plant that's a no-no is the "milkweed vine." But that has edible fruit much like a chayote... so again, I keep it.

If you're really allergic to strawberry guava, I apologize. Wish I could come over and dig up a dozen or so to plant here.

Aloha Ajit-

I'm in Hawaiian Acres right now!

do you have albizzia in the area? they build excellent soil very quickly. if you have a few years, you can plant albizzia, let it grow, and then cut it down and plant your fruit trees right next to it - it will break up the rock, create biomass and add lots and lots of nitrogen. no need to bring in the backhoe! don't introduce them to new areas though!

a good NFT (nitrogen fixing tree) for your area is Gliricidia. so easy to propagate and vigorous, and not very weedy at all. Acacia angustisima is another good one, altho more weedy. Calliandra cathyosus (that's spelled wrong) is another good one, and has beautiful flowers. much more weedy than Gliricidia thou, so be warned.

perennial peanut is an excellent ground cover. it's not gonna out compete the pilau miale though. hardly anything will, it seems. luckily, pilau maile isn't that hard to eradicate - just make sure to cut it back before it goes to flower! as a side note, the leaves are edible as a steamed spinach. if you can get past the smell (eww!)

chipping up the strawberry quava for mulch is a great idea, but you can also just cut it down and pile up the logs - hugelkulture style. maybe grow some Oyster mushrooms on em, or at least Turkey Tails. less fossil fuel use.

for quick establishment, the backhoe idea is solid. bust up the lava as deeply as is feasible, mulch it really heavy (1'+) and give it 6 months. then plant your trees. they will love it.

get a dump truck to drop off a load of mulch from the municipal green waste. 20 yards cost me about $150 - may be different for you

send me a PM if you got any questions.

aloha
Kaiwiki Clay

Are you living on the property? Do you make even occasional trips to or from it and a nearby town? Those are both opportunities to acquire organic matter for mulch and compost. Make the site into a nutrient trap. Nothing brought in should leave, or be sequestered out of root reach. This means humanure, urine, pet wastes, natural fabrics, and any and all paper products, as well as more "conventional" composts and mulches. A vehicle moving between a town and the site can be bringing back more, hopefully for free....cardboard if nothing else (useful for mulching around plantings and suppressing the weeds and invasives). On only two acres, these processes will make a big difference, especially if applied in one concentrated area in any given year, in just a few years' time.

Aloha thank you for the responses. Good to hear some ideas from a food forest neighbor in Hawaiian Acres.

1. Yes, I am trying to be careful and not introduce any new invasive species into the area. No albeezia in the surrounding area. I saw a square site full of albeezia on Leilani Estate for sale, the trees were humongous and the soil was probably very fertile, but to fell and chip the tree would have cost a fortune, besides the adjuring property also was full of Albeezia.

2. The agriculture extension agent also suggested Gliricidia I was contemplating using it for a live fence, but definitely as of green manure as well, I was uncertain of the weediness, encouraging to hear your experience with Gliricidia. ,

3. Compared to some of the sparse lava property on Orchid land; this property is extremely verdant, I am determined to experiment with growing fertilizer and bio-mass. I am trying to avoid bringing in any external inputs. Cutting the strawberry guava and using mushrooms to speed up the decomposition is an excellent idea. I've read many good things about our fungi friends on soil fertility. "Mycelim Running" was an inspiration.

4. The tricky part and uncertainty is how to deal with the existing invasive species and avoid a never-ending maintenance nightmare. I am experimenting with a small area first and see what happens.

Kaiwiki Clay, I will contact you for recommendation on source of Gliricidia, mushrooms and other things. Thank you all for your generosity in sharing your knowledge.