Assessing The Ability Of Two Soil Types In The Removal And Retention Of N And P Nutrients From Fish Pond Effluents.

Abstract

Effectiveness of two soil types found at Sagana, Kenya, black clay soil (eutric Vertisol) and a red clay soil (chromic Cambisol), in retaining nutrients from pond effluent was investigated. A laboratory experiment was conducted with soil columns containing either of the two soils. Pond effluent application intensities of 31, 81 and161 mm day-1 were tested on both soils. Both soils retained over 60% of total P from pond effluents, with red clay retaining 27% more P than black clay. At the high effluent loading rate, low % N removal was observed in both soils. Total N removal efficiency declined with time after 21 days at the high rate, and after that time no N removal was observed where red clay was used. Black clay was more enriched by N than red clay, while P enrichment was higher in red clay than in black clay. It appears that land application can remove substantial amounts of P and N from pond effluent.