Development of Nutrient Management System for Environmentally Sound Terrestrial Seawater Agriculture

Terrestrial seawater agriculture that utilizes pure seawater or seawater-based aquaculture effluents as irrigation sources to produce crops along barren coastal deserts, would play a potential role in supply of sustainable food to feed the world's ever-increasing population. The feasibility of seawater agriculture depends first on finding salt tolerant plants and second on developing matched agronomic technology. Among 1300 halophytes (naturally salt-tolerant plants) collected worldwide, Salicornia bigelovii Torr. has been identified as the most promising one for seawater agriculture. This plant can produce high yields of edible oil, protein meal, vegetable tips, forage, and fiber on seawater irrigation. Its improved varieties as a seawater agricultural oilseed crop are under release by USDA. Matched technology of seawater irrigation has also been established to effectively prevent salt accumulation in the rhizosphere. However, terrestrial seawater agriculture in practice has been challenged by nutrient management problems that arise from leaching and runoff of applied fertilizers through frequent irrigation on sandy soils where it occurs. The consequence of nutrient leaching includes not only greatly increasing the overall production cost due to fertilizer inefficiencies, but also potentially causing eutrophication of ground water. Therefore, our Phase I research attempts to find a best-suited way to control nutrient losses in seawater agriculture. The research is proposed to reveal the minimal and cost-effective plant requirements for nutrients that are not supplied by irrigated seawater and to investigate the feasibility of foliar application of required nutrients in the form of fertilizers.