3.4.6. Building Soil

A few simple rules for soil building and health soils

• Keep soils protected. This can be done by covering with plants, mulch, leaves or living mulch (such as sweet potatoes) at all times. Uncovered soil, especially in the tropics, loses nutrition rapidly through offgassing of nitrogen, drying, erosion, and destruction to soil life.
• Keep soils alive. Beneficial bacteria and fungi help boost the immune systems of your plants, keep pests away and provide more nutrition to your plant, and ultimately, to you. Soils stay alive and healthy when kept protected, not allowed to dry out and stay dried out, and they have sources of food for soil life, which to soils would be organic matter and minerals.
• Feed the soil, not the plant. Focus on providing living elements to the soil to keep it healthy and diverse. This includes organic compost, manure, leaves, any kind of organic material.
• Feed the plants, too. Ensure there is enough food for plants in the soil as well - meaning nitrogen, phosphorus, potassium, calcium, and trace minerals. Different types of plants need varying quantities of each of these. In poor soils, you will have to continue to provide this at least once per year at first, depending on how intensive your system is. If you build your system properly, at one point, the system itself should provide its own nutrition from leaf drop, animal manure, etc. Some sources of plant food: Manure, human urine (diluted 10-1), seaweed, compost, cover crops.
• Consider using charged biochar. This is wood charcoal and it creates a stable element in Florida sand and other poor soils which allows soil to continue to build. It must be “charged” with something - human urine, compost, manure, or other nutrition, or it will end up pulling nutrition out of the system instead of putting it in.

There are dozens of ways to build soil. If someone tells you there is one best way, they probably haven’t tried others, frankly. This is a good thing because it gives you some freedom to design soil building to fit your lifestyle, your particular site and your resources.

Also, keep in mind that if you understand WHY we’re using the materials and techniques we use to build soil, you’ll be able to better design your own system.

We share here some of the basic tricks we’ve learned over the years that can save you some time and a learning curve, but feel free to design your own solutions or tweak ours, while keeping these tips in mind.

Your designer hat is important here as much as anywhere. You can save countless hours of work if you spend some thoughtful observation time before jumping into soil building. The way that you do it can be as important as what you do - for instance, where are you going to put your compost system? If it’s far away from your kitchen, how workable is that?

We took some time teaching you about different types of soil, because different soils need different remedies. You might end up settling someplace that has very different types of soil than your current location. You may even discover that you have more than one soil type on your land.

Understanding what type of soil you have can save you a lot of time and headaches in the future. Some people have great soil to start out with. There is a lot less of that in the world than there was a century ago because we’ve messed a bunch of it up, but the point is, there are gradients to how much you need to do on this topic. The tests that you did should give you a good idea of where you stand with that.

Some indigenous tribes have had water keepers and soil keepers, those whose job it is to ensure the soil and water stays healthy and cared for. We like the concept a lot. We are striving to be water and soil keepers for ourselves, our children and the next seven generations.

Chop and Drop

“Chop and drop” is permaculture slang for chopping down weeds, small trees, and cover crops and dropping them into the system to simulate a forest floor environment with plenty of biomass to protect and build soils. This action of concentrating organic material where it is needed in your system has been used in many cultures to varying degrees around the world for thousands of years.

This is our favorite way to maintain soils over the long term. We might bring in manure, wood chips and other material to slam dunk systems, but using weeds and other plants on site to feed your system is a key part of the strategy of creating permanent systems. It is less work over the long run, and allows you and the system to become more self-sufficient.

The concept is: nature provides continual nutrition on her own. It’s up to us to work with her energy instead of resisting it by trying to suppress all weeds. Instead, let some weeds grow, or plant some material that creates great biomass (like moringa), harvest or cut down any unwanted organic material on your site, keep it on your site and use it to build soil.

Depending on what the plant is, you can either make piles that compost in place, add it to your compost pile, or “chop and drop” it right into your food forest (I prefer the latter; it’s less work). This is where you really start creating regenerative systems - by using the abundance that nature creates on her own.

Chop and drop uses what nature produces on your own site to feed your plants. Weeds, weedy trees and grasses that grow prolifically on your site without any aid could be treasured, not hated. These can be a key part of creating a “permanent system” that can survive on its own.

One of our favorite weeds to chop and drop is Spanish Needle (bidens). It grows prolifically in disturbed areas and can take over garden beds. Rather than resist it, we chop and drop it. But it’s such a survivor that if part of the stem touches the earth, it can reroot and regrow. So we pile it up in a mound and let it completely die off, and only then do we drop it into the system.

It’s also important with weeds to time the chop and drop. Chop them before they seed. When you do that, you get the benefit without having those seeds come up in volume in your garden or food forest where you will have to weed them again.

We like to let the weeds go in the wild areas or edges of the farm and bring them into the food forest. We also have sections of the food forest where we let them grow and literally chop them and drop them where they grew. This builds soil for future planting that we are planning. We like that we can concentrate so much biomass in the areas around our trees, and our trees really love it! They respond with massive fruit bounty and healthy, disease free growth.

Syntropic agriculture is a system designed to accumulate matter and energy, becoming more complex over time, all in order to create abundance. It is a form of process based agriculture, where working with the plants on site allows us to build long term fertility, as opposed to chemical agriculture that requires dependency on outside inputs and experiences entropy, degrading over time.

Syntropic agriculture uses principles very similar to permaculture principles, working with nature. We’ll cover more about this in our next section.

Chopping and dropping has always been a core part of permaculture but many people don’t really do enough of it to help the system to fully flourish. Ernst Gotsch, who developed this type of agriculture, goes above and beyond and adds massive amounts of chop and drop to his syntropic systems.

If your system gets to the point where you don’t have to bring in any outside material to feed it and maintain abundance, you truly have “permanent agriculture” happening.

As part of your system, you may want to plant plants that create fast biomass in edge space in your yard that you can periodically chop and drop. Some examples in Florida are lemongrass, vetiver grass, fakahatchee grass (native), moringa, and a variety of nitrogen fixing trees.

In northern systems, try comfrey, honey locust or various grasses. Almost any fast growing plant with low nutrient needs can be used as chop and drop.

In every region, there are fast growing trees, often nitrogen fixing, that will handle being repeatedly chopped and dropped. Not every tree can handle this, but many can. These trees often have many uses, but a great feature is the ability to continue to produce biomass after being cut back.

We planted a row of nitrogen fixing trees, Enterolobium cycloplum, as a trial to see if they will withstand chop and drop. When we chop these back, the roots die back too and release nitrogen and organic matter into the soil near our fruit trees. Over time, they haven’t been able to handle repeated chopping, but “weed trees” in our system like laurel cherry (Prunus caroliniana) or crepe myrtle have a better response.

Below is one of our favorite chop and drop trees, Elephant Ear tree, or Enterolobium cyclocarpum. This tree has many uses, but a great feature of this and many other nitrogen fixing trees is that you can cut it down dozens of times and it will keep growing back. Thus, it makes a great chop and drop. We’ve planted a row of these trees, which get quite huge if allowed to grow, right next to our mulberry orchard. When we chop these back, the roots die back too and release nitrogen and organic matter into the soil near our fruit trees.

You can chop off individual branches, like this one, or chop the entire tree down. It will grow back fast. Chop and drop trees are on the left, and a row of mulberries is on the right.

This biomass will provide the functions that a mature forest system provides to both soil and plants by protecting the soil, providing a diversity of organic matter (leaves and wood), feeding our hugelkultur system (see below for definition), preserving moisture, and in this case, releasing nitrogen into the soil not only from the leaf drop but from the root die back as well.

We let these trees grow a bit in summer as they provide some light shade protection to our mulberries in the heat of summer which they appreciate. We have used cuttings from these trees to cover vulnerable plants for frost protection in winter. These trees have other uses as well including fodder, medicine, wood, and more.

For successful chop and drop:

• Choose plants that grow well and fast without assistance in the native soil of your site.
• Include “weeds” in your chop and drop scheme.
• Chop weeds before they seed - a calendar is useful.
• Focus the drop around key planting areas, especially at first.
• Chop and drop more than you think you need - you’ll build a robust system fast.

Every weed, leaf and fallen branch has great value to your food production. Don’t throw it away or burn it to get rid of it. Capture that energy!

Mulch

A wood chip mulch of 3-4” deep can retain water for days beyond a regular bed of soil. It can save plants from drought in case of irrigation failure. It protects the soil from damage from sun, wind, erosion. It also creates a rich environment for beneficial insects, microbes and helpful fungus. We like oak mulch on garden beds as this will convert to beautiful soil over time and also creates a beautiful, healthy fungal network. Other mulch like pine or cedar will break down more slowly and thus need replacement less often, which may be a more important goal. We’ve used every type of wood and it all breaks down eventually. I won’t ever buy redwood or cypress mulch nor will I cut down trees just for the mulch. These trees are precious and becoming more and more rare, and there are other ways to landscape than by cutting down the few that are left.

We often start our beds with 2 feet of wood chip mulch. Three feet is not too much mulch in Florida sand. Yes, that's a lot of mulch but it means less work later because you'll have a stable bed that you can continue to build soil on. In better soils, this much mulch is likely to be counterproductive. In humid tropics and subtropics with sandy soils, 2 feet will break down to 6” within a couple of years, and you will have a lot more organic matter in your sand, especially if you add biochar, compost, manure, chop and drop, etc. This is one way I’ve found to build permanent soil in Florida if soils are sandy - lots of mulch mixed with other organic material and biochar.

Adding logs and sticks helps the system to persist even longer than just straight wood chips. We usually line the edges of beds with those.

Mulch can help remediate heavy clay soils as well as sand. Note that wood chip mulch in cold or dry climates sometimes takes a very long time to break down. In those climates, instead of using two feet of wood chips to create soil, I would use more nitrogen rich materials like manure, leaves, compost, dried grass, food waste, etc. You can add logs and sticks to line the edges or underneath the mulch for moisture retention.

Covering your soil with mulch protects it from wind, sun, and weeds and continues to build soil.

Use wood chips, pine straw, weeds or grass (with no seeds), straw, leaves, “chop and drop,” or other organic material.

Three inches is the minimum protection you need.

Don’t stack mulch, especially wood chips, up against the trunks of your trees. It’s a disease vector when touching the trunk. Keep it no closer than 6-18” away from the trunk. It’s a huge benefit there.

Where to find mulch

Sometimes your landfill or waste company will collect mulch and either deliver or let you pick it up. We’ve gotten many truckloads of mulch from our local landfill. We also keep an eye out for when utility companies come by yearly and trim tree branches back, and we let them know we’d like their mulch dumped in our yard. This is very convenient for both of us and saves fossil fuels as they now don’t have to drive to the dump to unload it.

You can often talk tree companies doing work in your neighborhood into dumping their truckload at your place once they’re done for the day. It saves them a trip to the dump and the expense of dumping.

We’ve also called tree companies out of the phone book - sometimes you have to sweet talk them or persist to get them to come - they will drop it off for you when in your neighborhood so ask first if they sometimes come there. We have never paid for mulch, but if you’re having trouble finding free sources, that is an option too. Just don’t use cypress or redwood or other endangered trees, please!! Those mulches don’t break down and they aren’t what we want to put in our living systems in any case. We want to build systems that will continue to create their own soil.

Growing food right in the mulch pile is a side benefit. Here we have cassava, squash and in the back of the pile, sweet potato, which does fine growing in straight wood mulch. Note that in Florida, that mulch pile will break down fast over summer. This one is partially composted after a few months.

Sheet mulch or lasagna gardening

This technique is more useful for annual gardens that have high nutrient needs. You can make beautifully composted soils right on the beds you’re building through the creation of layers of “brown” (carbon rich) plus “green” (nitrogen rich) organic material. Examples of brown include wood chips, leaves, brown grass, aged manure. Examples of green include fresh grass or other green plants, food scraps, seaweed, coffee grounds, fresh manure, urine. Add biochar to stabilize the beds, and rock minerals or granite dust for minerals.

Sources include (always check so that you can exclude things that are sprayed or contain toxics): neighbors, cafes, juice bars, horse stables, beaches, etc. I sheet mulch 2-3 feet of material. This will break down to 6 inches within 1-2 years in Florida. Sheet mulch can be used to create beautiful vegetable beds that will be relatively stable if biochar is used. You will have to add compost or more mulch yearly, but less each time. This is because vegetables do not build soil, but use it up. Using cover crops like cowpeas during the summer, and chopping them and using them as mulch, is an easy way to add material.

By layering these materials and ensuring each layer is wetted down until moist, you create the conditions to make beautiful soil quickly that you can plant right into. You can use this principle to create “fertility donuts” around newly planted trees as well. Just layer brown and green in a wide donut around the tree (see “No Water Tree Planting” in the next section of the course).

There are dozens of ingredients you can put into sheet mulch. Toby Hemenway, a top permaculture designer who passed away, created a formula for “bomb proof sheet mulch.” It has a great mix of minerals and nutrients, and structural support. It works great in Oregon, where he lived, and a lot of temperate and other areas. But we've found that the kitchen sink method also works great.

Our philosophy is that you can create a fantastic sheet mulch with ingredients available to you locally, if you understand why Toby did it this way. He put the nutrition on the bottom to encourage the roots to move down and integrate with the soil below. It also encourages worms or other soil creatures to start that integration process.

But in Florida, whatever you put on top of the sand is going to sink in with no problem - no need to make it easier. Because nutrients tend to disappear in sand, we would put the nutrients like minerals and manure higher, and a layer of cardboard or banana leaves right on the surface, to allow the nutrients more time to aggregate.

In Florida, straw is not something that is readily available in most places, or grown locally, so we simply don't use it. Instead, we use pine straw, wood chips, leaves, seedless weeds and other local materials. And we recommend that you cover your compost with at least 3” of brown material on top because of the heavy rains and sunlight.

The point is, you have to think with your ecosystem and soil types when designing your mulch.

Another point is - creatures move all that stuff around. It doesn’t stay in nice little layers. We find sand in the topmost layers of our sheet mulch within a few months. How did it get there? Creatures. Think of them as the digestive system of your soil. If you eat a nice, beautiful layer cake, it doesn’t look like that when it comes out, right? Yeah, same thing with soil and the compost or digestive process of living soils.

Hugelkultur

In certain areas of your yard where you don’t want to water much or at all, cover the area with about 3” of grass clippings and water these down thoroughly. Cover those with banana leaves, and then cardboard and soak again. Lay a couple of layers of logs down and add wood chips to fill in the spaces between the logs. Soak thoroughly. Add 18-24” of sheet mulch to the top of this (you will be close to 3 feet high, but it will sink down fast).

You are basically replicating the fertility and moisture retaining capabilities of a forest floor. The grass clippings “seal” the ground; the logs hold moisture and nutrients, as does the sheet mulch. This will help add some extra nutrient holding capability in your raised beds and reduce water needs.

Another method of doing this is to dig down about 8 inches and place the logs mostly underground. It’s a lot of work but the system stays there for a long time. It works better in a perennial system than an annual system but I’ve used it in garden beds to good results.

For our orchards, we dig a horizontal trench along our hillside, drop logs, branches and wood chips or weeds into it, and plant the trees on the downslope. This trench is a catchment for water and nutrients, which can then build up near where the tree can access it.

Swale with hugelkultur on the left side, and nurse logs plus chop and drop on the downslope (right). You can see how sandy our soil is, the trees appreciate any biomass we can give them. We’re slam dunking a forest ecosystem for these trees. Logs are placed in a ditch dug on contour, and the berm and logs are covered with chop and drop or wood chips.

This system captures nutrients and moisture in our low nutrition, sandy system, and does so for years with only chop and drop added to the system. We will plant mulberry, rosemary, lemongrass, aloe, other herbs, opuntia cactus and other crops on this berm, and additional crops between berms. We could add cassava to provide some wind/shade protection and other elements of support as well, which we’ll get into in more depth later.

You can also use logs as “nurse logs.” We add logs around our trees because fallen logs offer so much energy and beneficial fungi and other life to permanent forest systems. We surround our trees with a donut of fallen branches or logs from other trees. There are many different ways to do this.

This is a “fish scale” berm aligned to catch water and nutrients around the tree. Logs are place around the edges and a few inside the hole, manure, wood chips and chop and drop cover the berm and logs.

We planted an olive tree in this spot which will get very little care from us from here on out other than once per year chop and drop and possibly, watering in a severe drought. We will place larger logs nearby when we chop up a tree that fell down nearby. This allows the logs to continue to perform an ecosystem function for wildlife, but also provide energy and protection to specific trees we add to the system that could use some support.

Olives would survive here on their own, but will do better with this support (as would most trees).