In order to cope with current and future climate change it is interesting to explore food production techniques and strategies already tried and tested in countries with hot/dry climates.
N.B. Everything depends on the context! Permaculture is about putting the right thing in the right place at the right time and then connectiing it to the rest of the system. When we don’t have enough information or when we are convinced that a technique or strategy has ‘universal properties’ (it can be used everywhere regardless of the huge differences in local conditions) we create more problems than we solve, which is not good.
Pit gardening (Zaï, Chololo, Mantengo, Ngoro and Tassa)
Much less known in Europe than raised beds, this method of “gardening in pits” is found in many countries on the western side of the African continent. This form of land managment was boosted in the 1980’s by Yacouba Sawadogo who filled the Zaï with manure. One of his ideas was that the manure attracted termites who help break down the organic matter. A difficulty with termites is their tendancy to destroy young plantations. They can be controlled by running chickens through before planting.
Unsuitable for :
places where there is only a shallow soil depth.
heavy clay soils with little drainage in temperate zones where, due to rain, the pits can overfill with water.
Advantages
Loosens the soil
Increases soil fertility
Increases runoff infiltration
Creates microclimates
Accumulates organic matter
Simpifies irrigation
Construction
Dig holes 15-50 cm, with a distance between pits of 50-100 cm. In general, the pits are staggered. Place compost and mulch in the pits and plant your seedlings. Plant a mix of plants in each pit to optimize the use of space. For example (it depends on the size of your pits): one or more plants that will grow high, like corn. Another will cover the ground, one or two gourds for example. And finally a climbing plant like beans that fix nitrogen. Sometimes we call this guild* of plants “the three sisters”. But it is above all the principle that is important and not the name! In other countries this guild may consist of cassava, groundnuts and maize.
The photo above shows pits planted with corn, ideally the rest of the surface is protected by a ground cover crop such as sweet potatoes, peanuts or pumpkins. A firther step is to plant trees on the cultivated area to provide shade, organic matter, fix nitrogen, provide wood and tree crops.
In some areas where there is high levels or precipitation during the rainy seasons crps are planted on the raised areas around the pits. When the season has passed the pits are used again.
My farm is in the Ardèche region of France. After this season, 2021, I will be remaking the vegetable production area and installing pits. I won’t be using Zais I will be building the type of pits that one finds in Tunisia and other countires with similar climates. These can be about a square metre in size and are about 30cm deep. They have the same advantages as Zaï but are geometrically better adapted to my system.
* A guild in this context is a mixture of companion plants but can also include animals.
Tips: pits can be aligned or follow contour lines. The earth that is dug to make a hole is used to make a small earthen wall on the downslope side of the pit.