Submitted to: Journal of Environmental Monitoring and Restoration
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/20/2007
Publication Date: 9/20/2007
Citation: Zhang, M., Sparrow, S., Bechtel, P.J., Pantoja, A. 2007. Characteristics of nitrogen and phosphorus release from fish meals and fish hydrolysates in subarctic soils. Journal of Environmental Monitoring and Restoration. 3:262-275. Interpretive Summary: The expanding of organic farming in Alaska demands alternative nutrient sources for crop production. Annually, there are over 1,000,000 metric tons of fish by-products produced from the Alaska fishing industries. These fish by-products are rich in nitrogen and can be processed and used as a nutrient source for crop production. The first objective of the research was to determine rates of N and P release from 1) protein hydrolysate made from salmon by-products; 2) commercial fish meal made from Alaska pollock by-products; and 3) commercial fish bone meal made from Alaska whitefish by-products. The second objective was to develop simulation models for predicting fish meal N release in the field. Incubation experiments were conducted in the laboratory and the field. Two soils with or without fish byproducts at 100 µg N g-1 soil were incubated at 10 and 15oC for 56 days in the laboratory, or placed in plastic bags and incubated in two field locations. Soil samples were taken during the incubations and analyzed for mineral N and Melhich 3 P. Single exponential models were used to simulate mineral N release. The results showed that the cumulative mineral N release of each of the three fish byproducts followed a typical two-stage release pattern, i.e. a fast release phase until 7 days followed by a slow release phase. In the laboratory the amount of mineral N released in 56-day incubation was similar among the three fish byproducts. There was very little P release over the course of incubation. The single exponential model was suitable for simulating N release for fish meals, and that was validated by the field incubation results.
Technical Abstract: Fish harvested in Alaska waters contributes about 60% of total fish harvest for human consumption in USA. The annual seafood harvest is over two million metric tons and after processing, there are approximately one million metric tons of fish byproducts. These fish byproducts, depending on the fish species and components, vary in nutrition concentration. Laboratory incubation experiment is an approach to determine the amount of N released from organic nutrient sources in soil. Some Alaska farmers are ready to go to organic for two simple reasons, 1) the farm scale in Alaska is relative small, a few acres to several hundred acres, and as such, farmers can’t compete with the imported conventional farm products from the western United States; 2) the organically and locally produced farm products can give the farmer a higher premium than the conventional farm products. Because of short growing season, using legume as a rotational crop to increase soil fertility is limited. The organic producers heavily rely on domestic compost from plant residues, and fish by-products. The objectives of this research was: 1) to compare N and P release from three fish by-products in two major soils in Alaska; and 2) to determine a kinetic model/models that can be used to predict N release of fish by-products in Alaska soils.