Document: PAU-3-61-9

Ecological and resource recovery approaches to reduce the environmental impact of aquaculture production.

ADLER, P.R.*

USDA-ARS, Kearneysville, WV 25430 USA ¹

Abstract:
Agricultural production has become regionally specialized leading to the spatial separation of animal and feed production. This spatial separation has led to nutrient imbalances in watersheds and increases in nonpoint source runoff losses of nutrients to the water environment. When animal manure is viewed as a waste, storage in lagoons is a common management and treatment alternative. Anaerobic storage of manure in lagoons, however, degrades its value by increasing offensive odors and air pollutants and reducing organic matter and nutrient content. As a resource, value-added processes are used to maximize its value, thereby opening up more market options. In contrast to technological solutions, ecological approaches are less capital intensive and by using ecosystem services, have reduced operating costs. Two nutrient streams from the production of rainbow trout [solids (~10% dw) and overflow water from off-line settling basins for aquaculture solids] were the focus of this study. Solids were mixed with a range of carbon sources from switchgrass and barley straw to hybrid poplar, willow, pine, and oak over a C:N ratio gradient. Course mesh bags filled with the mixture were placed on the soil surface and changes in mass and nutrient content were measured over time. Mass loss from the mesh bags was used as a measure of the bioprocessing rate by the soil ecosystem. Carbon source had a greater effect on mass loss than C:N ratio in this study. Mass loss and N and P sequestration varied with carbon source. Sequestration increased with C:N ratio, but P sequestration was N limited. Overflow water was passed through a carbon biofilter in which microorganisms utilized the carbon source and nutrients from the water for their growth. More than 95% of the total suspended solids was removed, but performance varied with carbon source. Carbon source is a critical design parameter in optimizing ecological systems for resource recovery.

Keywords: agroecology, litter quality, phosphorus

This abstract is being presented at: 5:00 PM in session:
Oral Session #31: Agroecology.