How to build soil and grow vegetables in the rainforest?

Hello all!

First of all, Thank you for creating this great forum, so much info and inspiration to find here!

I am looking for any tips or info on how to build soil for growing vegetables in rainforest soil and climate.

I am working on a land in the Sucumbios area of Ecuador. The land used to be part of the Amazonian rainforest, but 15 years ago or so it was cleared and planted with grass to feed cattle. In 2007 it was bought by a lovely man who has slowly reforested it with native trees and plants, and also many fruit-trees and a cacaoplantation. The place also serves as a lodge where volunteers of different environmental projects are based. I am one of them, and part of my work in the project is to create a vegetable garden where we can grow food for the residents at the lodge. The hope is also that the place may serve as an inspiration and an example to show the local communities that it is possible to produce food here, sp that they dont have to be dependent on expensive imported goods. I also want to do some research on the traditional growing methods of the indigenous cultures here, to see how that corresponds and complements permaculture teqniques.

So thats the context! The challenge is that the soil here seems to be very poor of nutrients. From what I understand all the nutrients and biomass are tied up in the trees and vegetation, and the processes of decomposition and recycling goes so fast that there never builds up a humus layer. When I examined the soil in different places there is thin layer of darker soil on the top, like 1 cm. And below that there is just sand and clay, no roots, no animals. Also the rainwater is flushing through the soil every days, rinsing out the nutrients into the river-

My thought is to get a lot of organic material into the soil. We have made a few banana circles with a pit in the middle filled with organic material, leaves and trunks and some cacaocompost.
We are also mulching all the beds, constantly putting more organic material on to them.

I am also trying out a theory that is more or less my own reasoning, havent found anything on internet on this but the idea is inspired from the bananacircle-tecnique. I would be very happy for feedback on this!
The land slopes down towards a river in quite soft hillsides. In a flatter area below the slope we have planted pineapple and bananas in rows perpendicular to the slope. In between two of these rows we have dug a canal, almost like a swale, it is about 50-60 cm deep, 60-70 cm wide and maybe 10 meters long. We have filled the canal with lots of wood, trunks and branches from trees, and more organic material on the top to create a composting process in the canal that will feed the plants with nutrients and build up soil.

My thought is also that the rainwater that flows down the slope is bringing with it nutrients from the soil above, these are normally washed down into the river but I want to try and catch and store them instead. The theory is that the trunks will absorb some of the water and that the nutrients will cycle in the composting process that is going on in the canal. The excess water i hope will run of. I dont want to create a swale full of water.
Any thoughts on this? Has it been tried before?

And in general I am very happy for any tips and experiences on growing veggies in this climate. Also tips on vegetables that are possible to grow here are warmly welcome!
I have only worked with permaculture in my homecountry Norway, where the climate is quite different... it is very interested to learn about this type of ecosystem and practice permaculture thinking here.
I will only be here for two more months so most of the things we are doing now are just experiments, to see in time how it works.

ok, sorry for long question..Very grateful fior feedback

Hi Asa,

An in-depth set of questions like this is hard to answer completely in this setting, but some thoughts based on our experience in Costa Rica.

-abandon the idea that you are going to grow western style temperate veggies, such as tomato, eggplant, etc. This is possible, but very difficult due to pest pressure and the intensity of the rain. Focus instead on tropical perennial vegetables such as Katuk, Chaya, Okinawan Spinach, Kang Kong, etc. These are the low hanging fruit of tropical gardening. ECHO in Florida is a great resource. This requires an adaption of the diet away from western temperate foods that many of us transplants grew up on.

-you are asking the right questions about indigenous diets. Try and learn what folks ate 50, 100, 500 years ago. Often the most nutritious crops are semi wild and consider "poor" folk food. Re-discover these.

-your understanding on the nutrient cycle is right on. So in practice this means don't try and build soil or humus, that is for temperate folks, just add lots of organic matter, and keep adding. Build the plant infrastructure so that you have a constant supply of mulch from coppiced and pruned plants, preferably legumes.

-raise the garden beds and focus on biochar and bioferments such as EM or Indigenous MO, compost teas, etc.

You are on the right track, due your due diligence, start small, and pay attention to the feedback.

Saludos
Scott

Consider biochar. You can read lots more about it on this site and elsewhere. It's a technique used since ancient times to build soil in Amazonia and elsewhere. Basically plant material is charred....partially burned. This can be done quite primitively, and smokily, by getting stuff burning and then smothering it or quenching it, or if you are able you can make various sorts of containers to make it in, some of which can also be used for cooking, water heating, and other uses for fire. Turning organic matter into charcoal makes it much more durable in the soil....you will actually gain soil organic matter quicker in your climate, even though 2/3 or more of the total material is lost in the fire......this is because the soil microbes have a much harder time breaking down the charcoal. Inoculate the biochar with urine and manure and you have an excellent soil amendment.....

Hello Scott and Alder!

Thank you so much for taking the time to answer me! Lots of good feedback and tips!

Yes, biochar i definitively on the list. We have a oven allready. So it is just to start producing and experiment with it in different ways. Compost teas seems to be a good teqchinque. I will study it more.

The link to ECHO was great! Found lots of useful info there. It is a big study to understand the plants and systems here. Today there is a big meeting here between local indigenous comunities so I hope to talk to them about their growing methods and traditions and create contacts for the future.

So, I take it that my "logs in a swale"-idea is not the best way to build soil?
Better to keep mulching without digging?
What about hugelkultur? To raise the beds and get lots of organic material?

One thought for logs in the swale was also to inoculate the logs with mushrooms. The project I am volunteering for is working to develop a method to break down oil contaminants in soil and water by using fungi and bacterias. We are in a very early fase though, studying and experimenting with differnt species to see how we can use them in remediation, but also as a food source. So I am trying to integrate possibilites for this into my design.

And while I am at it here I'll throw out a question on cacao aswell! There is a plantation of cacaotrees here, but they are not very productive, they are planted as a monoculture and the fruits are badly affected by some sort of fungus.
I want to introduce more plants into the system to make it more diverse and resilient and I am trying to make a plan and design for this. Found some good info on net, but if you also happen to have any experinece with cacao I would love to hear about!!

Scott, is there a website or such with info on your place in Costa Rica?

Many Thanks and Best wishes!

Åsa

Asa,

Could you update us as to what you have decided? I would suggest that you contact the local permaculturists in Ecuador for some ideas. There are a few in and around Quito. You may also ask at the local technical university's ag department. Also, USFQ has done some work in Amazonia.

You can make a simple kiln out of barrels, to turn leaves and slash into char. If you need to improve a large area, it would be more economical to use the older slash and burn method. There is nothing inherently wrong with slash and burn, as long as it is used within a rotating system. The Amazon supported a much larger population on rotating slash and burn, before disease and slavery nearly eliminated the native population.

Tomato and eggplant are hardly temperate crops. They are tropical perennials that have been adapted to grow annually in temperate climates. You can find varieties in Ecuador that will flourish in your climate zone. There are also some delicious related species, such as tomatillo, tomate de arbol and naranjilla.

You might also want to study what has been done in Tome-Acu, Brasil http://pt.wikipedia.org/wiki/Tom%C3%A9-A%C3%A7u (use google translate, if you don't read Portuguese). Look up CAMTA and JICA for more references. It is a model that has proven very successful.

Also, consider perennial peanut (Arachis pintoi) as a nitrogen fixing cover crop for your cacao and other tree crops.

Good luck

Hello Asa. Sounds like you are on the right track. You should be able to make biochar easily enough by digging a swale/trench, adding the organic material to burn, and then smother it with the material you dug out. I would then treat it as a lasagna bed, and simply after a season of letting it settle, plant your crop. Spraying compost or worm tea on your beds over time will add microbial activity to your soil as well. Raw milk works the same.

About your cacao, I would mix it with banana plants which will offer the cacao shade. Like coffee, cacao grows best with little to partial sun. We have a young cacao plantation, and some are under shade of the banana plants. The shaded cacao is literally twice as tall as the ones in full sun. It's quite amazing.

We are in the SE Amazon of Peru, btw.

If leafcutters are an issue, here is a powerful trick. Find two leafcutter mounds, fill a wheelbarrow with material from one including live ants, and add the material to the second leafcutter mount, and vice versa. The ants will pack up and move on when they detect the scent trail of the opposing leafcutter ant mounds.

Hope the tips help.