Cover Crops The basic idea of cover crops is to keep something living with leaves covering the ground and roots holding the soil to prevent the soil from getting washed away. Stacking functions is the permaculture way of saying kill two birds with one stone or preferably three or four birds! What can cover crops do other than conserve soil?
- Fix nitrogen
- Attract beneficial organisms
- Repel pests
- Add organic matter
- Out compete weeds
Some examples of these multi purpose plants we use are:
- Ground Covers are low growing plants that spread out over the ground
- Cow peas and peanuts fix nitrogen as well as provide protein rich food. When planted under cassava they are tilled into the soil when the cassava is harvested. Cow peas can be harvested multiple times for eating or selling before being let to grow rampant so when the cassava is harvested the leaves are tilled into the soil.
- Sweet Potato and pumpkin out compete most weeds, can grow almost anywhere, can live in compost and help finish the breakdown process, and provide both leafy green vegetables and starchy tubers or fruit.
- Desmodium is a beneficial weed that fixes nitrogen and inhibits the germination of striga seeds. Striga is a parasitic plant that attacks corn. It can take over so it is good to prune it and leave the leaves as mulch.
- Alley Cropping are mid story sized plants that are grown along the curvature of a hill to catch descending water and stabilize a slope. These are often planted on the ridge of a swale. It is convenient to plant an understory of a cover crop.
- Sunn Hemp has root exudes that repel nematodes. It also attracts beneficial insects and soil organisms. It blooms during the dry season giving bees a source of food. The prolific branches can be cut and fed to goats, used for mulch, and fiber for rope.
- Pigeon Peas fix nitrogen and make delicious high protein peas. They flower in the dry season providing food for bees. The prolific branches can be cut for goat food and mulch.
- Moringa is one of the world’s healthiest foods. It is highly medicinal as a topical application for cuts as well as a delicious vegetable. It fixes nitrogen and has high market value. It needs to be coppiced to keep it small and the branches can be used to plant more moringa, feed goats, and even make raised beds.
Tanks are awesome but expensive. For a tank to be installed first a solid, flat foundation needs to be poured. Then the piping and tank attached to a metal roof. The tanks have to have a solid foundation or they will break. Sometimes they break even with a solid foundation. If the job is to be done correctly a filtration system should be installed with UV lights. However without electricity and capitol for fancy filters people make do with chlorine treatments and or boiling.
A terraced garden we made in Hawai’i. The foreground shows the final terraced and banana, coconut mulched garden.
Swales and terracing are used to catch water. Swales are when ditches following the contour of a hill are dug and the dirt is mounded downhill. Often ally cropping is done on top of the swale to lock the mounded dirt into place. The ditch catches water allowing it more time to seep into the ground instead of running off downhill. Terracing is combined with the swales flattening out sections of the land. This increases surface area and makes working on the land much easier. Living terraces can be made by growing plants such as moringa horizontally forming a small wall or ally cropping to stabilize a swale. Other terraces can be made by stones or tires though tires need to be covered because they release toxic compounds when hot. We also made a water barrel terrace that stores water and stabilizes the slope.
Agroforestry is a beautiful way to produce crops. The essence is to create a usable forest. The forested hilltops capture rain and the roots allow it to flow underground making its way downhill over a matter of months rather than minutes as runoff. To create a forest we look at the canopy and fill up the space similar to how a forest is structured. While many crops get higher yields when grown alone, total farm outputs are higher in an agroforestry system. In areas of the coast that have not been displaced by colonialism we can see the traditional agroforestry system which once dominated to coast. Areas such as ours displaced by colonialism have been deforested forgotten this system. Having a poly culture gives the system greater nutrient and carbon capturing ability, greater disease resistance, erosion control and high diversity of yields meaning better nutrition for people and soil.
We need to think about sun/wind/water, stacking the canopy, sacking the roots (deep roots, wide roots), and functions such as medicine, fiber, nitrogen fixers, pest repellents, and food meaning vegetable, fruit, flavor, starches.
We start with stacking the canopy. On the coast our over-story is coconuts. Coconuts fall into just about every category. They provide roofing material, antibacterial cloth, fuel for fires, cooking oil, water, probiotics, alcohol. They allow plenty of sun to penetrate their branches for the plants below. Their roots are wide and branching. The width of their reach brings in many nutrients making their leaves excellent mulch. The highly branched nature of the roots allows them to hold onto soil making them perfect in valley bottoms affected by floods. Here is a pretty picture about how amazing they are.
Learn how the coconut tree provides all-around benefits — from its husks and roots to coconut oil — through our infographic “Plant of Life: An Infographic on Various Coconut Uses.” Use the embed code to share it on your website or visit our infographic page for the high-res version.
Under the coconuts in an upper mid story of mangoes, citrus, bananas, papaya are traditionally grown. Some non-traditional but useful trees are noni (medicine), breadfruit (which mulches itself very effectively and provides a starchy fruit), jack fruit, and sour sop.
In a lower mid story are plants like coffee and cacao with high market value, sunn hemp for fiber, beneficial microorganism attractant, bee and goat food, and nematode repellent, pigeon peas for nitrogen fixation , bee and goat food, delicious high protein peas, Moringa for medicine and vegetables.
Below these are plants such as sweet potato, taro, pumpkin which all have leaves for vegetables as well as starchy parts and act as ground covers. The under story is a good place for herbs as well.
Here is an example diagram of an integrated farm model.
Lighting and passive cooling go hand in hand in our home. The front windows let in light and air.
The air gets sucked out through the stacked roof. We arranged the roof so when the sun sets it bounces off the metal roof giving excellent lighting until the sun is below the horizon.
Wine bottles make up the fruit of our Baobab tree. The necks are used to hang our clothes in our room.
Windows can be made by filling water containers with clean water and a cap full of bleach. I added a bit of pipe glue when I screwed on the caps just in case. These can be embedded in the cob or wrapped over if making a earthbag house. When the sun shines directly through them they cast rainbows throughout the room.
Organic Matter is carbon containing compounds. The benefits of organic matter are improving soil structure, improving water holding capacity, increasing nutrient holding capacity, capturing carbon, and increasing beneficial microorganisms. Tilling exposes soil organic matter to sunlight which burns it off.
Biochar is the addition of charcoal to a soil. These are stable carbon compounds that sequester carbon, improve soil structure and fertility. We buy our charcoal dust from a neighbor that produces charcoal. This gives him extra revenue as well as cleans up his yard. Find out more about biochar.
Compost is the stable organic compounds, humus, that is created when organic matter is broken down. Our sources of organic matter include:
- Mulch from our trees on our fence line that feed the goats and are then spread on the farm. After 1 month the mulch has broken down into compost.
- Fruit and vegetable scraps from the market feed our black solider fly larvae. We then use the castings as compost fertilizer.
- Weeding and trimming the yard for mulch as well as dropped coconut branches and coconut husks.
Organic Matter in the soil is stable carbon compounds called humus that makes up an essential part of the soil structure.
By adding organic matter to the soil we can create carbon capturing farming. Organic matter is a vital part of the soil. It increases cation exchange capacity which is a fancy way of saying it holds onto nutrients so they don’t get washed away yet makes them available to plants. Organic matter retains moisture as well as creating a soil structure that allows more water to permeate into our clay soil. A farm is only as successful as the amount of organic matter it can accumulate. The future depends on a farming system that can capture carbon rather than releasing it. This release happens when soil is tilled and exposed to sunlight which breaks down the compounds into CO2. The tilling also injures beneficial fungus and if you kill your friends, you won’t have any friends.
We have only an inch to two inches of top soil.
Erosion means death to the future. There are two main ways erosion happens, wind and rain. However there are also numerous factors that influence this happening such as land use.
Wind is easily dealt with. We planted nitrogen fixing trees and shrubs for a fence line that gives us not only a wind block but also a beautiful privacy screen, security fence against marauding animals, and goat food which then turns to mulch and fertilizer. Mulch and cover crops keep the soil covered so the wind can’t pick up the soil particles.
The main way water erosion happens is when the force of a rain drop hits bare soil causing particles to splash down hill. During heavy rain events muddy rivers form. On bare slopes this can mean a foot or more is carved out along an erosion gully in one rain event. All of this sediment floods out onto the reef destroying biodiversity and fishermen’s livelihoods.
How can we keep these muddy rivers from forming?
Since colonialism 96% of Kenya’s trees have been cut down. In deforested areas the rain hits the slopes baked hard in the sun. The water quickly runs off gathering momentum and with it precious soil. A day after a large rain the soil is hard and dry again. However in undisturbed areas of the coast one can see the villages on top of the hills nestled in among their traditional agro forestry system of coconuts with mangos, citrus, papaya, bananas, and others underneath. When trees are planted on the crowns of hills they slow the rain and the roots give water paths to travel underground. Not only does this minimize mass flow of water it also keeps down slope moist for longer periods of time with the water moving slowly under ground.
o Specifically where we had our farm the sub soil is impermeable shale pressed together with clay. We used papaya as a biological drill. The deep herbaceous tap root drives deep into the soil. We kill the papaya and use it as mulch. The tap root dies and quickly rots leaving a deep hole filled with organic matter. This allows more water to permeate deep and flow underground making the farm more productive.