Contributions of systematic tile drainage to watershed-scale phosphorus transport.

摘要: Phosphorus (P) transport from agricultural fields continues to be a focal point for addressing harmful algal blooms and nuisance algae in freshwater systems throughout the world. In humid, poorly drained regions, attention has turned P delivery through subsurface tile drainage. However, research on contributions of drainage watershed-scale losses is limited. The objective this study was evaluate long-term movement its manifestation at watershed outlet. Discharge data associated concentrations were collected 8 yr (2005-2012) six drains outlet headwater within Upper Big Walnut Creek central Ohio. Results showed that accounted 47% discharge, 48% dissolved P, 40% total exported watershed. Average annual loss 0.98 kg ha, 0.48 ha. loads discharge tended greater winter, spring, fall, whereas greatest summer. Over 8-yr study, transported represented 90% all measured exceeded recommended levels (0.03 mg L) minimizing algae. Thus, results show systematically tile-drained watersheds, amount delivered surface waters via cannot dismissed. Given relative typical application rates, development implementation best management practices (BMPs) must jointly consider economic environmental benefits. Specifically, BMPs should focus late early spring seasons when most loading occurs.