Evaluation of lime-based ditch filters for reduction of phosphorus loses from agricultural land

Abstract

Leakage of nutrients from agricultural land is one of the main causes of eutrophication of the Baltic Sea. The international project “BalticSea 2020” carries out research and measures to reduced leakage from agriculture and seeks to bind phosphorus leaching from agricultural land in the ditch close to the source, thereby reducing the discharge of phosphorus to the sea. The results obtained in Lithuania show that the efficiency of tested filter materials varies widely during the reporting period. Mean concentrations of total phosphorus (TP) in the outflow from all tested filter materials differed significantly from those in ditch water. The filter material Polonite was distinguished by highest reduction capacity of TP (57% on the average). Slightly less reduction (by 49%) was determined using Granulated blast furnace slag and the least (26%) using Filtralite-P. Reduction capacity of phosphate phosphorus (PO4-P) was a few percentage points lower: Polonite – 52%, Slag – 44% and Filtralite-P – 20% on the average.