Reviving Deserts with Syntropic Agroforestry
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Desertification is one of the major problems we face today. Deserts are spreading in places that were bursting to life and offered good productions a few decades before. Unsustainable agricultural practices are mostly the cause of it. While mankind is capable of destruction, it can also be responsible for the rebirth and regeneration of ecosystems.
I wish to start my article with a quote from Masanobu Fukuoka;
“Desert formation is not due to the absence of rain, but the rain ceases to fall because the vegetation has disappeared.”
My syntropic agroforestry educators taught me the same thing: most people think that to plant, you need water, but to have water, you need to plant—very densely and diversify it. So here is our first lesson: we should not leave bare soil, but our soils should always be covered with decomposed or preferably living organic matter.
A second issue I wish to address is that the lack of rainfall is not the primary cause of desertification, but the lack of organic matter in the soil is. The lack of organic matter prevents soil from retaining/withholding water. Water evaporates or runs off if it cannot penetrate the soil. Heavy rainfall can happen in most arid climate zones, but due to the unbreakable and warm soil surface, combined with the lack of fertile topsoil and organic matter, all that precious water will be wasted. However, if we can only add 1 % extra organic matter to the soil, the water holding capacity will increase to 150.000 liters of water per hectare!
Syntropic agroforestry focuses, for that reason, in particular, on applying/creating thick layers of mulch. The source of that mulch is the so-called biomass crops planted on our farms. Certain African savannah grasses are planted and can be chopped every three weeks to provide a constant stream of organic matter that is added to the soil, thus increasing water retention. We also plant biomass trees for that same purpose.
But what if the situation is so deprived of life, making it challenging for grasses and trees to grow? In that case, we must find species capable of surviving these harsh conditions. We could think of species like cacti or succulents. These unique plants are often found at the beginning of a natural succession. According to syntropic agroforestry, succession describes the natural tendency for energy accumulation. In this process, these plants create circumstances that are more suitable for other plants that need to capture more energy. Typical pioneering plant species are weeds, invasive species, cacti, and succulents in deserts. Cacti and succulents have one crucial characteristic that makes them special: even in the most severe droughts, their leaves or pads are always full of water.
Water that they certainly cannot find in the soil. Succulents and cacti harvest water from the atmosphere. Their spikes or leaf structure, together with the coolness of the surface of their leaves, enable water vapor to condense. That water sucked in/penetrates the spikes.
If we take the two quotes I started this lecture with, we might get an idea of what our approach could be. Those strong and resilient plants can be planted in high densities (higher than they would grow in nature). This soil cover prevents evaporation and erosion, and the sunlight captured by their canopies is transformed by photosynthesis into energy (food) and keeps the soil cooler.
Here is why this is so important: water vapor moves from hot to cool. Desert soils can be very hot. So all water evaporates immediately. However, cool soil reverses that stream, pulling water vapor closer to the soil where all those cool succulents are waiting to absorb it.
What is the role in this succession?
We can accelerate those processes by planting more drought-resistant plants very densely. Secondly, we can chop and drop the leaves and organize them as a thick layer of mulch. That decreases the temperature of the soil and maintains it close to 20 degrees Celsius. That cooler soil with dense layers of decomposing organic matter will increase water concentration in the soil, making it possible for other plants to grow now. Thanks to those syntropic principles, we can regreen deserts even without irrigation.
Further reading
The Importance and Way of Layering Plant Species in a Syntropic System
Water Conservation Measures: The Role of Mombasa Grass in a Syntropic System
The Impact of Syntropic Agroforestry on Water Usage and Farm Resilience
