We have only an inch to two inches of top soil.
Erosion means death to the future. There are two main ways erosion happens, wind and rain. However there are also numerous factors that influence this happening such as land use.
Wind is easily dealt with. We planted nitrogen fixing trees and shrubs for a fence line that gives us not only a wind block but also a beautiful privacy screen, security fence against marauding animals, and goat food which then turns to mulch and fertilizer. Mulch and cover crops keep the soil covered so the wind can’t pick up the soil particles.
The main way water erosion happens is when the force of a rain drop hits bare soil causing particles to splash down hill. During heavy rain events muddy rivers form. On bare slopes this can mean a foot or more is carved out along an erosion gully in one rain event. All of this sediment floods out onto the reef destroying biodiversity and fishermen’s livelihoods.
How can we keep these muddy rivers from forming?
Since colonialism 96% of Kenya’s trees have been cut down. In deforested areas the rain hits the slopes baked hard in the sun. The water quickly runs off gathering momentum and with it precious soil. A day after a large rain the soil is hard and dry again. However in undisturbed areas of the coast one can see the villages on top of the hills nestled in among their traditional agro forestry system of coconuts with mangos, citrus, papaya, bananas, and others underneath. When trees are planted on the crowns of hills they slow the rain and the roots give water paths to travel underground. Not only does this minimize mass flow of water it also keeps down slope moist for longer periods of time with the water moving slowly under ground.
o Specifically where we had our farm the sub soil is impermeable shale pressed together with clay. We used papaya as a biological drill. The deep herbaceous tap root drives deep into the soil. We kill the papaya and use it as mulch. The tap root dies and quickly rots leaving a deep hole filled with organic matter. This allows more water to permeate deep and flow underground making the farm more productive.