Aquaculture Pond Modeling for the Analysis of Integrated Aquaculture/Agriculture Systems: Fishpond Organic Matter and Nitrogen Dynamics

digestibility if the models are to accurately simulate organic matter transformations in fish ponds. This is especially true for pond management systems that utilize non-conventional feed and fertilizer sources. Munsiri and Boyd (1995) showed that, with the use of a single first-order rate constant to model organic matter degradation, equilibrium conditions were reached in a relatively short time, and organic matter accumulation rates were overestimated. The inadequacy of such an approach has also been recognized in marine sediment models. For example, Jorgensen (1979) recommended that organic matter be divided into different groups of compounds of different reactivity, each undergoing first-order decomposition. This report describes the modifications made to the modeling of organic matter dynamics in fishponds and presents preliminary results for fish growth rates, nitrogen, and organic matter accumulation obtained by the modified models. Introduction