Phosphorus content of ditch sediments as indicator of critical source areas (Research Note)

Authors

• H. JANSSON
• V. MÄNTYLAHTI
• A. NÄRVÄNEN

DOI: https://doi.org/10.23986/afsci.5662

Abstract

An inexpensive method for identifying high phosphorus (P) loads on ditches carrying water from critical source areas ("hot spots", i.e. manure-affected areas) was tested. Water flowing from the hot-spot areas is rich in dissolved nutrients (e.g. P) and nutrient-rich eroded material. In this study the water from hot spots contained an average of 2.2 mg/l dissolved reactive P but field ditch water 0.14 mg/l. We selected 62 ditches with varying P-load levels for sediment analysis. Five ponds and 16 lakes were also studied. The sediment samples were analysed by the AAAc-extraction (0.5 M ammonium acetate, 0.5 M acetic acid, pH 4.65) method used for routine soil testing in Finland. The analysis of sediment AAAc-P proved to be a useful method for identifying ditches carrying high P waters from hot spots. Half of the ditch sediments in the hot spot ditches showed high or excessive P concentrations. AAAc extraction of the sediment is less expensive than water analysis and the sampling can be extended to periods when no water flows in the ditches.;