Abstract

Abstract.—Aerated ponds did not accumulate as much carbon in bottom soils as control ponds. Application of urea to manured ponds did not accelerate carbon loss from bottom soils. When ponds were drained for fish harvest, appreciable carbon was eroded from the surface layers of bottom soil. Further decomposition of soil car-bon occurred during the 5-week drying period between crops. Within-pond variation in soil carbon concentra-tion was high; a technique for selecting replication and sample size requirements for experiments on changes in bottom soil carbon concentration is provided. Excessive accumulation of organic matter in soils of aquaculture ponds is detrimental. High con-centrations of soil organic matter increase oxygen demand and favor development of reducing con-