Perhaps you are asking yourself: why should we discuss seawater irrigation?
The simple answer is: due to the impacts climate change, the world is seeking renewable sources of energy as alternatives to a fossil-fuelled energy matrix. Only around 0,5% of freshwater is directly available for human consumption and 70% of freshwater withdrawals are consumed by agriculture. Yet, saltwater drenches 2/3 of our planet, not to mention saline groundwater which underlies much of the land. Also, there are about 20,000 linear miles of sunny, desert seacoast with untapped potential. Bearing this in mind, let us focus on a specific challenge, or opportunity: desert economics. No, this is not about oil being pumped out of the earth!
Too good to be true?
There are two basic questions regarding desert economics which must be addressed. Firstly, does salt water allow for plant growth? The answer is yes, and abundantly, just think of seaside mangroves. One halophyte (salt-tolerant plant) in particular, Salicornia, has great benefits and potential. Salicornia is a sea vegetable rich in minerals and vitamins A, B1, B15, C, and D. This plant is also a great source of oils and can eventually be produced to power jets, as Bilal Bomani, a senior NASA scientist believes:
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| ''So we talk about ideas worth spreading, right? How about this: In sub-Saharan Africa, next to the sea, saltwater, barren desert: how about we take that plant, plant it, half use for food, half use for fuel. We can make that happen, inexpensively'' - Bilal Bomani's TED TALK: Click here to watch! |
Dr. Carl Hodges, the scientist behind the first seawater farm, argues that Salicornia grown in desert regions can potentially replace today's soy production, eliminating one of the main threats to the sustainability of rainforests (NASA reports that soybean cultivation for biodiesel was responsible for destroying 325,000 hectares of Amazon rainforest in 2007). Hodges also argues that, if adopted on a global scale, seawater irrigation could even contribute to reducing rising sea levels, though I couldn't find further explanations. I imagine that, at the farm level, taking sea water inland could help remediate the impacts of flooding under a small rise in sea level.
So how does it work?
The desert transformations proposed by seawater farming are ambitious, aimed at creating a self-sustaining ecosystem which harbors flora, fauna and biodiversity. To do so requires investments in infrastructure, namely, the digging of canals and lakes.
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| A Self-Sustaining Ecological Farming System With Sea Water based on Carl Hodges Seawater Farm in Eritrea/ Source |
The diagram above is based on a particular seawater project conducted in Eritrea. A first canal with pumps that lift the seawater is needed and a secondary series of canals and lakes become home to a flourishing aquaculture of fish, shrimp, and mollusks. The biological waste from the aquaculture activities become the fertilizers needed to support the production of Salicornia. Nothing is wasted; the resulting water irrigates lands, replenishing depleted wetlands, revitalizing mangroves and ecosystems which provide essential and valuable services. A veritable virtuous circle.
According to CN Hodges, in its four years of operation in Eritrea, the Seawater Farms project planted 250 acres of Salicornia and nearly 240 acres of seawater forest. The exportation of shrimp was an additional value which provided incomes and employed nearly 800 people.
Today, other countries are experimenting with Salicornia and other saltwater tolerant plants as sources of food! What do you think?
For more information on seawater farming:
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