"Fertility of the soil is the future of civilisation." Albert Howard
Seaweed is fantastic for the soil, it's full of nutrients and soil conditioners, as well as being sustainable. Alex and friends collected barrels of red algae that had washed up on the shore in Tarifa. We rinsed off the surface salt and soaked it in water for 2 months: turning it into liquid fertiliser.
We used organic municipal waste, straw, and seaweed after soaking. We made lines along contours, and put straw and seaweed around individual trees. Olive tree chips made from pruning will be next to mulch along key lines and paths.
In the areas we have planted tree crops we first planted leguminous seeds, beans and peas that fix nitrogen, between our mulch lines. Our school visitors helped, which was wonderful to see. This was to suppress weeds and provide green manure for when the trees are establishing, it will be mown or left to die down naturally to avoid soil disturbance.
Everything is aimed at minimising the need for irrigation. This includes mini berms and swales, and building mini terraces by hand using rocks lying around the ground, to help hold and infiltrate the rain when it comes.
We dug some bigger ditches initially as berms and swales, but decided they made more sense as buried woody compost heaps, known as hugelkultur. We had a lot of woody material to bury! These hold moisture in the soil, and encourage fungi which join up helpfully with growing plants. We have now planted these with fruit trees and shrubs.