Reversing desertification in a semi-arid climate — Mértola, Alentejo
The Baixo Alentejo is one of the most arid territories in Europe. With less than 500mm of rain per year, summers exceeding 40°C and compacted schist soils, desertification is not a future threat — it is the present state of much of the landscape.
Decades of intensive agriculture have left soils without organic matter, without structure and without life. When it rains, water does not infiltrate — it runs off. When it is hot, bare soil reaches 70°C at the surface, killing any seed.
The result is a vicious cycle: without vegetation, soil degrades. Without soil, vegetation cannot grow.
Mértola receives an average of 450mm of annual rainfall, concentrated in 3-4 winter months. Summer lasts 5 months without a drop of rain. Soils are mostly nutrient-poor schist, with acidic pH and low water retention capacity.
This is the context where Wild Alentejo operates. It is not an easy place to regenerate — which is exactly why the data has scientific value. If it works here, it works in any semi-arid Mediterranean climate.
The approach at Wild Alentejo is not gardening — it is ecosystem engineering. Every decision aims to accelerate the organic matter cycle and restore the soil's capacity to retain water and sustain life.
The core principle is simple: soil must never be bare. Biomass mulch, sheep wool and living ground cover form a thermal and hydraulic insulation that completely transforms the microclimate at 10cm depth.
Stratification pruning is not destruction — it is accelerated fertilisation. By cutting pioneers and leaving biomass on the soil, we inject organic carbon directly where mycorrhizal fungi need it.
Biomass mulch + sheep wool + living cover. Soil never exposed to direct sunlight.
Pioneer biomass cut and deposited on soil. Organic carbon in closed cycle.
Underground network activated by absence of herbicides and constant organic matter input.
13 hens in rotation: natural nitrogen fertilisation, surface tillage, pest control.
Each species was chosen not only for fruit or shade — but for its specific function in soil regeneration.
These are not theoretical models. They are direct field observations, comparing zones inside and outside the agroforestry system, on the same soil type and solar exposure.
In August, bare soil reaches 68°C at the surface. Inside the system, with coverage, the maximum temperature is 42°C — a 26°C difference that means the difference between life and death for soil microbiology.
In heavy rain, bare soil runs off 80% of water. In the covered system, infiltration is almost total. Every mm of rain stays where it falls.
At the start of the project, no earthworms were visible. After 3 years, 12-15 are counted per spade in areas with thick mulch. A direct indicator of soil health.
Direct observation of humus layer forming under mulch. No formal laboratory analysis yet, but soil colour and structure have visibly changed between 2022 and 2025.
Each adopted plant directly funds system maintenance — mulching, pruning, irrigation and monitoring. From €1/year.