Fertilization of Earth Ponds. I: Effects on Physico-Chemical Characteristics and Eutrophication of Pond Water and Soil

Abstract

Various biomanipulation strategies, using inorganic and organic fertilizer to improve oligotrophic conditions were carried out in earth ponds in Central Scotland U.K. over a period of one year. Replicate ponds were treated with low and high phosphorus (LP, HP) high phosphorus and nitrogen (HPN), low and high chicken manure (LC, HC) high chicken and cow manure (HCC) and tow untreated controls (CTRL). The effects of treatments on physio-chemical parameters of the pond water and soil suitable for trout culture was also evaluated along with primary production. There was generally remarkable improvement in eutrophic condition with respect to water and soil qualities. Water pH rose steadily from 7.0 - 7.5 at pre-manipulation state to 7.73 - 8.39 in the CTRL, LP and HPN in response to liming and fertilization. Soil pH was generally acidic in the range, 5.80 - 6.64 in both organic and inorganic fertilization. Differences in nutrient (ammonia, nitrate and phosphate) concentrations were consistent with fertilizer application. Nitrite showed an initial decline in CTRL, LP and HP, but there was an upsurge in HPN, which significantly varied (P < 0.05) with other treatments. High Biochemical oxygen demand (BOD) in HC treatment coincided with fall in dissolved oxygen (DO). The response pattern of primary production and chlorophyll - a (Chl-a) used as index of eutrophication significantly between treatments and periods (P <0.05). The significance of fertilizer application vis-à-vis water quality criteria are discussed in the light of contemporary in resource utilization and management, and an aquatic ecosystem undergoing transition from oligotrophic to eutrophic status.

Journal of Aquatic Sciences Volume 14, April 1999, pp. 5-12




KEY WORDS:

Fertilization, earth pond, water, soil and eutrophication.