Sulaiman Tejan Jalloh
Institute of Advanced Management and Technology
Freetown, Sierra Leone, West Africa
Introduction
Most of the dissolved chemical constituents or salts found in seawater have a continental origin. It seems that these chemicals were released from continental rocks through weathering and then carried to the oceans by stream runoff. Over time, the concentration of these chemicals increased until equilibrium was met. This equilibrium occurred when the ocean’s water could not dissolve any more material in solution. Similarities between fossilized sea life and organisms living today indicate that the composition of seawater stopped changing drastically about 600 million years ago.
Seawater Agriculture
It is, however, evidence that as the population of the Earth increases, the production of food becomes more and more of a problem in order to feed this growing number of people. One of the specific problems facing agriculturalists is the need for water. Fresh water is needed not only for irrigation but also for other human activities, and there is no process that is effective enough at desalinization to provide the volume of water human beings need. It is very important to also note that the top five plants eaten by people cannot tolerate salt, and these are wheat, corn, rice, potatoes, and soybeans. Since finding enough land and water to produce the foods needed by the world is an urgent problem, my concern now is how the supply of food can be augmented. My suggestion of one way is to find edible plants which can tolerate saltwater.
My essay is submitted with an intention to address the feasibility of seawater agriculture, which I conclude works well in the sandy soils of the desert environment. Seawater agriculture is defined as growing salt-tolerant crops on land with water pumped from the ocean for irrigation. Desert land is plentiful, and so is seawater. However, only a small portion of available desert is close enough to the sea to make such irrigation worthwhile. My estimates stand that 15 percent of undeveloped land in the world comprises coastal and inland salt deserts.
This is proven on the western coast of Mexico. The team irrigated the plants daily by flooding the fields with high-saline seawater from the Gulf of California. The rainfall in the region averages only 90 millimeters a year. The team flooded the plots with an annual depth of 20 meters or more of seawater. The team was certain that the plants were growing almost solely on seawater. The yields varied among the species, and the most productive halophytes produced between one and two kilograms per square meter of dry biomass. This is roughly the yield of alfalfa grown using freshwater irrigation. However, to show that these halophytes were cost-effective, it was necessary to show that they could replace conventional crops for a specific use. The team thus tested whether halophytes could be used to feed livestock, and this was important in itself because finding enough forage for cattle, sheep, and goats is one of the most challenging problems facing the world today. Many halophytes would serve in that they have high levels of protein and digestible carbohydrates, but unfortunately, these plants also contain large amounts of salt. One of the ways these plants adjust to a saline environment is to accumulate salt. Salt has no calories.