
The intensive vegetable garden is based on Permaculture principles, which view the garden as an ecosystem and use a holistic system approach management.
We produce vegetables and greens to 29 000 meals a year and we use the following organic farming and permaculture techniques which consists of:
Soil protection and enhancement
The intensive garden at the Academy is 5000 square feet and has sandy and acidic soil. In order to grow organic vegetables, fruits and herbs it is necessary for the topsoil to have a structure that:
enables retention of water and nutrients
provides a cool and protected home for all the important microbes
To this end, many techniques are implemented daily to:
- improve the structure of the soil
- reduce soil compaction
- improve water cycling and capture
- boost plant growth
Composting
A main source of fertility of the intensive garden at RVA comes from it’s compost production.
Compost is made by placing layers of nitrogenous (green) organic matter - such as kitchen waste and horse manure - with carbon based (brown) organic matter - such as dried plant material and cardboard - into a pile. This layer combination provides the diet required by soil microbes to rapidly decompose the organic matter in the pile. At the end of the process, a high-quality compost is produced and provides an excellent fertiliser for hungry fruits and vegetables.
The teams have experimented with various compost systems over the years. Currently, there is a system comprising eight compost piles that are hand turned every week. These labour intensive piles, made up of fresh green leaves, dry brown leaves, kitchen waste, cardboard and horse manure; produce close to a cubic meter of compost per week.
Efforts have been made to find more labour efficient ways to produce a higher volume and better quality compost. For this reason, in the future, probiotic or efficient microbes will be introduced to the mix, to enhance the composting process.
Biocharing
Biochar is an excellent soil enhancer and carbon sequester.
It’s structure helps the soil keep its moisture and thereby its capacity to hold nutrients. Another benefit of applying biochar to the soil is carbon storage. The carbon in the biochar can stay stable for hundreds or thousand of years and thereby contributes to a meaningful carbon sequestration.
At the school, several experiments have been made to find the best way to make biochar. In 2016, a kiln was created, where the wood gas (pyrolysis gas) from the char chamber goes back to the fire underneath the char chamber, so more wood gas can be released and the charring process can go faster. Even though the insulation system still needs to be worked on, this kiln design has proven to be quite efficient. It provides the garden with a weekly production of biochar.
Mulching
Soft rotten wood, dry leaves and grass clippings are mixed with horse manure and biochar. This mixture is then applied to the top of the garden beds as mulch; to reduce soil erosion, control weeds and increase water retention. The mulch, itself in time becomes fertiliser, as it is transformed into rich humus by the soil microbes.
Every week, the mulch layer in the garden beds are maintained by the students and teachers. Making lasagna garden beds is a method that results in a rich soil with less work required. Several beds in the garden are lasagna beds. The name “lasagna bed” has nothing to do with what you’ll be growing in the garden. It refers to the method of building the garden beds, which is, essentially, adding layers of organic materials that “cooks down” over time, resulting in rich, fluffy soil that will help your plants thrive.
Complementary organic material
The lasagna bed, mulch and compost systems require a lot of organic material. For this reason, support species are grown in and around the intensive garden.
Support species are trees and veining beans that are capable of fixing nitrogen from the atmosphere.
They release nitrogen from the nodules on their roots into the soil to benefit surrounding plants. The organic matter, deriving from them, is also noted for its high nitrogen content. Therefore, these plants provide the soil with additional nitrogen value when they are pruned and their cuttings are used in mulch and compost.
Another example of support species is Vetiver Grass, which is used for erosion control as well as for mulch and material for composting.
Dispersed shade systems
Banana plants, Neem, Gliricidia and Moringa trees have been planted around the garden to provide filtered light into the garden and to hold moisture. This dispersed shade system (DSS) is an important part of the garden as it lowers the ambient temperature in the understory, creating an environment more conducive to the planting of vegetables; particularly during the hot dry months of March and April.
Organic Fertilizers
Plants are positioned on the garden beds according to their respective plant families. In this way, by mixing plant families, the nutrient and fertiliser requirements of the diverse plant families are naturally produced and therefore more easily met; than when growing a mono crop.
In addition, RVA students experiment with liquid fertilisers - most commonly in the form of compost tea, nettle tea, moringa tea and the liquid effluent from the biogas digester. They are applied weekly, either as a foliar spray or directly to the root of the plants.
Pest prevention and control
A Permaculture garden is an array of colors and shapes that hold a diversity of plant families and species. Some plants are specifically placed to attract beneficial insects whilst others have been planted to repel pests affecting nearby vegetables. Due to this design, the garden suffers minimal damage by pests.
When an outbreak does occur, students implement various organic pest control solutions. Neem, garlic, hot pepper and bacillus thuringus (Bt) solutions are typically applied as a liquid spray.
Polyculture
In the garden several different species are planted together in the same bed, according to their ability to coexist and benefit from each other. This biodiversity is important in sustaining the health of the intensive vegetable garden and the garden’s ecosystem. Areas with higher levels of biodiversity are able to adjust to changes in the climate and to prevent diseases. Polyculture is a more practical and economical way to grow food than monoculture.