Food Forest Site Prep: Improving Soil

Our sandy soil here in north-central Florida creates gardening challenges. It can’t store nutrients or retain water and there is little microbiology to create fertility. It is essentially lifeless. Yet the soil is key to our gardening success. How can we hope to nurture the garden of our dreams in it? We take early steps to improve it.

A useful first step is to establish the soil fertility baseline by getting a soil test. Tests can be done through a local extension office or through various online labs. There are even home test kits available, although it’s probably best to rely on a local professional for the most accurate results. Whatever form of analysis is used should give you an indication of how your soil needs to be improved. You’ll be asked to take samples from various areas of your land. Identify each with a label and make a sketch of the areas sampled, keeping records for yourself, then send the samples off to the lab. County extension agents can help you interpret the results and offer advice on how to improve your soil.

Florida county extension offices: sfyl.ifas.ufl.edu/find-your-local-office

*This was our “soil” before adding mulch … so much sand!*

When we moved into our current home, the lawn was a disaster. Whatever previous plantings had existed, were removed to help the owner (who did not live in the house full-time) stay on top of lawn care more easily. There was a small amount of Bermuda grass and a large number of weeds in the sandy soil. We’ve never been into manicured grass lawns for a number of reasons — and I had plans to make a food forest, so this didn’t bother me much. In fact, as a permaculture designer, I rather appreciated the blank slate to experiment with.

“The civilized nations have been sustained by the primitive forests
which anciently rotted where they stood. They survive as long as the soil is not exhausted.”

— Thoreau, Walking and the Wild

Regenerating the Soil

One of the best ways to grow successfully is to observe a natural system nearby and then attempt to recreate it in our own yard. Just across from our neighborhood is the Halpata Tastankaki Nature Preserve with oak scrub and sandhill habitats. The soil is sandy and nutrient-poor, but many plants flourish there including rosemary, prickly pear cactus, pawpaw, persimmon, and passionfruit. These areas can be brutally hot and dry and also get the occasional frost in the winter, but these plants thrive with no care at all. Now there are some low-maintenance plant choices to start with. Also native to our area: Chickasaw plum, beautyberry, red mulberry, yucca (Spanish bayonet), and several species of blackberries.

To imitate nature’s soil building techniques, nitrogen-fixing native plants such as sunshine mimosa, wild tamarind, Fakahatchee grass, and coral beans can be chopped and dropped. Other good nitrogen-fixers include moringa, pigeon pea, and daikon radish.

*Wild Tamarind is not the fruit-bearing kind, but a fast-growing, non-invasive Florida native. They make great pioneer plants and naturally phase out as other plants become established. When chopped to the ground, they will not grow back from the roots (Lysiloma bahamensis).

Most nitrogen-fixing plants are in the legume family. Bacteria surrounding their roots pull nitrogen out of the air and provide it to the plant. The plants, in turn, provide sugars that feed the bacteria. Nearby plants benefit from the added nitrogen in the soil. When plants are used for chop and drop, their roots release nitrogen into the soil. Chop and drop works best when our summer rainy season begins and the plant material will break down quickly.

I love using pigeon pea and comfrey. Perennial peanut was not terribly successful on our property. It kept disappearing. I couldn’t find a pest on the few remaining leaves, so I suspect rabbits. I also chop and drop Mexican sunflower, which grows and propagates prolifically here.

*Mycorrhizal fungi in our mulch have long filaments that resemble roots and have a beneficial relationship with nearby plants.*

The Magic of Mulch

Mulch truly works its magic in sandy soil. As it breaks down it not only adds organic matter, it retains water, creating an environment much more conducive to growing. Arborist mulch can be difficult to get these days though as it is now so popular with gardeners. ChipDrop didn’t deliver in my area and all the local tree services were selling their chips out of town. Because we have quite a few mature trees in our yard, whenever we need service, we negotiate a drop of the entire chipper truckload which can end up being substantial. They are motivated to keep things simple and book us as the last appointment of the day so we get the full load. Leaves and twigs in the mulch will also enrich the soil. There are some palm fronds in the mix, but not enough to bother me. I can either throw that part in the compost pile or try to keep it underneath the mulch I’m spreading. It will eventually decompose.

My husband worried about having mulch near our house, attracting bugs (and we never put arborist mulch up against the house). Termites also concerned him since we have an older wood-frame home. At one point a conga line of termites did pass through during their mating season. We decided to get termite bait stations (with sodium borate products considered “green” by the EPA) installed to eliminate future worries. The bait inside the stations doesn’t come in contact with the soil and is supposed to be safe for organic gardening. So — not something this organic gardener was keen on doing initially, but sometimes you just have to soothe the spouse and save the house.

I am not aware of any downside to arborist mulch. All the fears I have heard are based on misconceptions. Some are concerned that fresh chips will tie up nitrogen as they decompose, and it can be a temporary issue that can affect seed germination, but this won’t be an issue around trees or shrubs with roots deeper in the ground. Mulch should not be placed so it will come in contact with the trunk or stem of plants anyway. Mulch will begin to break down quickly here in Florida or any area with heavy rains, heat, and humidity. Some fear plant diseases will spread from arborist trimmings. Let it age in a pile where it will heat and destroy any pathogens if that is a concern. When I can wait, I’ll sheet mulch new areas and just allow them to stand unplanted for a while. Add arborist mulch to your garden with confidence that it will work its magic and improve the soil over time.

*Earthworms are very important in increasing soil health. They decompose organic matter, add nutrients, and aerate the soil.*

Inviting Worms to the Party

Vermiculture is another great way to improve the soil. Sheet mulch garden areas by laying out cardboard to eliminate grass and weeds, then covering with a layer of compost and topped by a thick layer of mulch. When short on compost, I often just use cardboard and mulch. The mulch breaks down pretty quickly into rich soil. It also retains moisture. The cardboard stays out of the landfill, breaks down into organic matter, and attracts worms. I’ve found that in our humid subtropical climate it rapidly composts in place. Very few weeds penetrate this protective barrier if the mulch is deep enough.

I have used indoor worm bins in the past but found a new low-maintenance method I’ll explain in more detail in another post. Short story: I keep it all in-ground and let the worms come and go as they please.

I use the sheet mulching technique during the rainy season and let it process without planting for as long as possible. If I really want to get something in the ground right away, however, I just add worm castings and compost to the area directly surrounding the new plant.

Create Compost

Don’t let those food scraps go to waste. Make compost! Aside from the usual fruit and vegetable parings, I also add some other odds and ends in the mix like coffee grounds/filters (I do buy ones that are designed to be compostable*), tea bags, torn-up paper towels, and toilet rolls, and brown paper packing material. Ashes from the fire pit (natural wood only) are also good for compost. Add a little soil from the garden to get some beneficial microorganism activity going. Throw on plant trimmings and fallen leaves. Water and turn it once in a while and have amazing compost to add to the garden in a few months. I compost in the shade and rarely turn it, but in the Florida heat and humidity my pile breaks down pretty quickly.

TIP: Do not throw everything into your compost pile. Most residential compost piles will not get hot enough to destroy the pathogens found in meats. (Piles must heat to at least 131˚ F for three days to kill pathogens that are dangerous for humans.) Who wants to risk attracting pests and having a smelly compost area anyway? No pet waste, no glossy paper, no diseased plants. Eggshells will add calcium to compost, but I always wash, dry, and finely crush them before adding them to the pile (or add them to worm bins for grit). Using a mortar and pestle is best as studies have found that powdered eggshells are readily available to plants, where large chunks can take years to break down. I choose not to compost dryer lint because some of the items I launder have synthetic fibers and I do not want micro-plastics in the soil where I am growing food. Again, we’re trying to emulate nature as much as possible.

Making the Most of Manure

In our area, there are a lot of horse ranches that offer free manure, but this needs to be aged or composted first to reduce the nitrogen to a level that won’t damage plants. Rabbit manure can be added directly to the garden or used as a green/nitrogen source in the compost pile. Rabbit droppings are higher in nitrogen and phosphorus than other manure. It is safe for use on food plants. It’s also odorless. Plus, red wiggler worms love rabbit droppings and will leave their own in the process. I’ve had chickens and goats in the past and working with their manure can be a bit labor-intensive. I may consider adding rabbits here. My only concern is the fox that frequently visits our yard. We lost our chickens to coyotes. I like my gardening to stay stress-free, so for now, I’ll stick to green manure and worm castings.

Wildlife Activity

Local wildlife is part of the natural ecosystem, which should be recreated as closely as possible for the best results. To that end, it is great if a food forest can remain unfenced. I regularly find armadillo furrows in my mulch, while the plants remain virtually undisturbed. I choose to embrace the armadillo chaos and enjoy the aerated soil. I’m always amused by sandhill crane visits. They do eat frogs, lizards, and insects — but I haven’t noticed them cause any damage. A neighbor feeds them, so often they just stroll through our yard and even seem to enjoy walking through my garden arbor. I have caught a single rabbit visiting an area with perennial peanut ground cover, but the population seems low enough that I’m not concerned. A fox also frequents our yard, so perhaps that is why. Gopher tortoises will pay a call on occasion too. Foxes and tortoises eat fruit, but can only reach so far, so I’ve chosen to make no effort to keep the local wildlife out of our yard.

The Benefits of Improved Soil

Improved soil results in healthy plants that are naturally resistant to disease and pests. A variety of organic amendments like compost, manure, or worm castings will improve the nutrient content of soil and stabilize the pH levels. Follow the tips above and you’ll have amazing soil in no time. Happy gardening!

Food Forest Site Prep