Integrated agriculture and aquaculture for sustainable food production

Abstract

As we have come to depend on aquaculture to supplement natural fisheries, intensive culture methods have increased production. Accompanying environmental damage--non-point source pollution, loss of biodiversity and struggle for water--has offset food and financial gains. Problems surrounding food production are amplified in arid lands, as the potential of irrigated agriculture is weighed against the value of water. Through the following research, I studied integration of aquaculture and agriculture through multiple uses of water and nutrients, to reduce environmental impacts. When managed properly, integration can provide multiple cash crops, increased food and fiber production with reduced inputs. Integration allows for groundwater and nutrients in water and solid waste to be reused. Shrimp farms in Arizona use low-salinity ground water from aquifers for shrimp ponds and agricultural irrigation. On one of these farms, effluent is reused for irrigation of olive trees and other field crops. In Chapter 3, I described an experiment designed to quantify changes in the height of olive trees due to irrigation with shrimp effluent. Trees receiving effluent grew an average of 61.0 cm over the two-year experiment, 70.4 cm with fertilizer and 48.4 cm in the well water treatment. No negative effects due to effluent irrigation were found, while increases in water use efficiency were realized by producing two crops with the same irrigation water. Multiple uses of water are also possible in smaller scale agriculture systems. I performed a financial analysis of a small-scale aquaponics system, integrated hydroponics and aquaculture, in Chapter 4. Biological viability of such systems is clear. By building and managing this system for five months, I examined economic viability, by analyzing annual costs and revenue. Calculating net present value showed that the system was not financially viable unless labor costs were excluded. Financial returns were between 3,794 and 10,640 over six years. In five months, this system produced 181.4 kg of food, with fish feed, iron and water as the only inputs. This study showed potential for using small-scale aquaponics as a hobby, in schools, and as a tool for agricultural economics education, but not as a business opportunity.