Saltwater Irrigation

Sea level rise and coastal inundation are changing the agricultural landscape around the world.

Scientists are working on halophytic (salt-loving) plants, including Salicornia bigelovii samphire (pictured). It is hoped that salt-tolerant agricultural ingredients will become staples of a global diet in a world where freshwater irrigation is increasingly unstable. Image credit: ICBA

…saltwater irrigation has been studied for decades, and experiments have succeeded while research and experiments have grown and demonstrated the viability of some plants such as halophytes that have the potential to change our conventional food landscape. What types of new crops can be developed for sustainable harvest, and what techniques can be invented to succeed without additional environmental damage?

One strategy is to retreat. This is what many coastwise villages and urban centers are considering, planning, and in some cases withdrawing from the most egregious areas of impact of ocean expansion and extreme weather. A second strategy is to adapt agriculture away from conventional harvest and to modify crops and methods to take advantage of, not run away from, the new conditions.

Saltwater irrigation has been studied for decades, and in some areas, most notably Israel, India, and some areas of coastal Africa, experiments have succeeded partially on a local scale when there is no alternative. But as the freshwater supplies diminish or are corrupted, and as the topography of the coastal land is transformed, research and experiment has grown and demonstrated some plants and some approaches can signal the possibility of change as an alternative to abandonment and defeat.

Our conventional food crops — wheat, corn, rice, potatoes, and soybeans — cannot tolerate salt. As these are central to our present diet, the threat of their loss, whether to the ocean or to inadequate freshwater supply, is a global threat, increased by population growth and food security issues. In this context of loss, however, there is no dearth of opportunity: salt water is available in copious amount worldwide, and an estimated 43% of Earth’s total land surface remains undeveloped and 1.5 % of that is coastal, millions of acres that could be brought into use for animal and human food production, without deforestation or further freshwater decline.

Two questions pertain: what type of new crops can be developed for sustainable harvest? And, what techniques can be invented to succeed without additional environmental damage? There are certain types of plants, called halophytes that, like many of the original food plants we currently enjoy, can be domesticated for food, forage, even fertilizer. Certain sea grasses are among thousands of halophytes that include natural protein and digestible carbohydrates suitable for human consumption. One salt marsh succulent, Salicornia bibelovii, contains levels of oil and protein comparable to soybeans, and have been the subject of field trials in Mexico, the United Arab Emirates, Saudi Arabia and India with yields that equal or exceed the output of other oil seed grown with freshwater irrigation. A farm in the Netherlands has succeeded in growing saltwater irrigated vegetables such as carrots, cabbage, onions, and potatoes, the latter particularly successful to the extent that four salt-tolerant varieties have been shipped to Pakistan where saline-damaged lands are being reprogrammed to test potato farming at scale. Technology has played its part, computer controlled pipes, seawater and fresh, mixed into irrigation water tailored to eight different degrees of salinity, the supply adjusted through drip irrigation that match the specific conditions and demands of the specific plant’s growth requirement.

The history of saltwater irrigation is a tale of a few determined, prescient plant scientists:

In 1949 Ecologist Hugo Boyko and horticulturist Elizabeth Boyko went to Eilat, a town on the Red Sea in the newly formed State of Israel to test their theories for saltwater agriculture and who published their results in Scientific American in 1967.

Edward Glenn, J. Jed Brown, and James W. O’Leary from the University of Arizona have promoted several examples as described here, along with others from the Arab world where the problem has been an immediate concern for a long, long time.

What seems interesting to me is the possibility of multiple, overlapping systems. For example, another Scientific American article by Claude E. Boyd and Jason W. Clay recently described the possible synergy between shrimp aquaculture, halophyte farms, fertilizer recovery, and compost production, with the need and waste of each applied to the need and waste of the next — new “natural assembly line,” a succession of innovations self-supporting and self-sustaining. If you add solar and ocean geothermal energy to power this integrated enterprise, and a desalination plant to provide drinking water and sanitation for the community and fresh water from the ocean to mix with the salt, you will have invented an entirely new approach to efficiently and sustainably provide the sustenance upon which life, now and to come, will depend.

PETER NEILL is founder and director of the World Ocean Observatory, a web-based place of exchange for information and educational services about the health of the world ocean. He is also host of World Ocean Radio, upon which this blog is inspired. World Ocean Radio celebrates 12 years this year, with more than 600 episodes produced to date.

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