We think of deserts as dry wastelands incapable of food production.  Surprisingly, there is often enough rainfall to support vegetation.  The problem is that most of this water falls only over the course of one week and pools in aquifers a meter below the surface.  A tree with a developed root system can survive from these aquifers, but seedlings need consistent moisture at the surface in order to fuel root growth toward these water sources.  A week of rain simply isn’t enough.  And if you dig deep enough to reach the water table, you destroy the natural capillaries in the soil that act as a permeable boundary to support the seed and transfer water.

Seeds grow from the dumbbell-shaped hole, steadily hydrated by the cylindrical reservoir. (Photo credit: Groasis)

Nature is full of examples of efficient solutions, and an unlikely model for success in retaining this moisture has been found in bird feces.  When a bird consumes a seed and excretes it onto the dry soil of a desert, its excrement serves as a retention system for moisture, allowing roots to grow. The nascent root systems immediately begins penetrating the soil and growing toward the water below.

The vital role that bird excrement plays in the germination of plant seeds is the central inspiration for the Groasis, a deceptively simple invention that promises to revolutionize aforestation efforts in arid climates.

The Groasis uses incubation to deliver water over a time-period in tune with a seedling’s demand for water.  Any precipitation from rainfall or evening condensation is collected from the fan-shaped roof of the device and stored in evaporation-proof containers. A small wick delivers a steady flow of water to the plant, gradually creating a water column in the soil to support long-term growth.  The water also regulates the plant’s temperature, cooling it in the day-time heat and insulating it at night.  When the plant is around two feet tall, it has already established a robust root system and can survive un-aided in the harsh climate.

AquaPro, the company behind the Groasis, has developed mechanized equipment to implement this growing system for large-scale rehabilitation projects.  In 2010 alone there were fifteen aforestation projects in Kenya, the United States, France and Spain that used the Groasis to help deal with strip-mining rehabilitation, desertification, and other problems.

Andrew Boyd is a research intern with the Nourishing the Planet project.

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