Agriculture and eutrophication of freshwaters: a review of control measures

Abstract

Agriculture contributes a larger percentage of phosphorus (P) to freshwaters eutrophication. Fertilizers and manures applications over a period of time lead to P soil build up exceeding the required needs of the crops. Excess P is transferred into the waters through runoff, erosion, leaching and artificial drainage which impairs water quality, restricts water use for fisheries, promotes harmful algal bloom of Cyanobacteria and Pfiesteria - which pose serious health hazards to livestock and humans. Many measures are taken toward the control of P loss from agricultural soil into the water. Tremendous reductions were achieved in the P loss concentrations from soil to water. However, these control measures could only help in reducing the concentration of particulate phosphorus (PP) which is associated with soil particles. Dissolved phosphorus (DP) still finds its way into the waters. Further efforts must be made toward reducing the P loss from agricultural soil into waters to the minimum levels.

Keywords: Eutrophication, Phosphorus, Freshwater, Agriculture