Subsurface Drainage Loss of Particles and Phosphorus from Field Plot Experiments and a Tile‐Drained Catchment

Abstract

Movement of particles by water through the soil can be a significant pathway for P transport to surface waters in certain soil types. Our objective was to describe and quantify particulate matter (PM), particulate phosphorus (PP) and dissolved phosphorus (DP) transport tile drains during controlled plot experiments. The results were compared to corresponding studies of natural storm events in the tile‐drained catchment as a whole. Six rain simulations (irrigation 15.3–37 mm) were carried out at two 25 m2 plots on a loamy soil. Tracer chloride concentration in the drainage water peaked within 1 h of the onset of irrigation, thus indicating rapid macropore flow to the drains. PM, PP, and DP concentrations were highest in the initial drainage flow: 63 to 334 mg PM L−1, 0.177 to 0.876 mg PP L−1, and 0.042 to 0.103 mg DP L−1, respectively. Particulate matter and PP loss rates measured for the rapid drainage flow response were in the same range in the plot experiments as for nine precipitation events in the tile‐drained catchment (13.3 ha): 171 to 630 g PM ha−1 mm−1 vs. 141 to 892 g PM ha−1 mm−1, and 0.57 to 1.75 g PP ha−1 mm−1 vs. 0.71 to 5.92 g PP ha−1 mm−1, respectively. Tracer analysis using 137Cs revealed that the PM in the drainage water was derived from the topsoil.

Soil Drainage as an Active Agent of Recent Soil Evolution: A Review

“…Such losses were of a similar magnitude than annual losses measured on similar soils by Petersen et al (2004) or Sogon et al (1999). At the event scale, particles were mainly transported to the drain at the early beginning of drainflow events, the maximum concentrations in particles being often observed before the peak drainwater discharge (Grant et al, 1996;Kronvang et al, 1997;Penven et al, 1998;Laubel et al, 1999;Petersen et al, 2004). Subsequently, both the drainflow and its particulate matter (PM) concentrations rapidly declined with time.…”

“…Laubel et al (1999) showed that loss rates were thus higher during the first autumn storm after the dry season than during winter storms. This seasonal trend was attributed to the gradual decrease of the easily available particle pool produced during the dry season due to both biological activity and soil drying (Grant et al, 1996;Kronvang et al, 1997;Laubel et al, 1999), but contradictory results are also reported (Petersen et al, 2004).…”

“…At the drainage outlet, Mercier et al (2000) measured exported particles finer than 2 µm and observed that more than 80% had a size below 0.45 µm. Laubel et al (1999) reported that the median size of the leached particles was smaller than 5 µm. Coarser particles, however, were transported via subsurface drainage network, but their size never exceeded 50 µm (Chapman et al, 2001).…”

“…In order to identify the origin of the exported particles, some of their properties such as particle size distribution, organic carbon, phosphorus or 137 Cs contents have been compared with those of the soil solid phases (Laubel et al, 1999;Mercier et al, 2000;Chapman et al, 2001;Petersen et al, 2002).…”

“…Laubel et al (1999) showed that loss rates were thus higher during the first autumn storm after the dry season than during winter storms. This seasonal trend was attributed to the gradual decrease of the easily available particle pool produced during the dry season due to both biological activity and soil drying (Grant et al, 1996;Kronvang et al, 1997;Laubel et al, 1999), but contradictory results are also reported (Petersen et al, 2004).Despite high inter-plot and annual variability, all studies agreed that storm events contributed to an important part of the annual particle losses. As an example, Laubel et al (1999), measuring soil losses at the drainage outlet at the storm flow event scale reported total soil losses ranging from about 1 to more than 10 kg ha -1 year -1 (Table III).…”