Agroecosystems Sustainability Center Associate Director Andrew Margenot gave the keynote address at The Fertilizer Institute Research Forum on March 19 in Dallas, Texas. Margenot’s address was titled Non-point source – and non fertilizer? – nutrient losses: the case of phosphorus.
Margenot reviewed evidence that current nutrient loss reduction strategies do not discriminate among non-point sources of nutrient losses, which include but are not limited to agriculture. Specifically, he noted that only a small percentage of streambank phosphorus erosion is recorded, yet it likely accounts for a much more significant amount of the sediment exported through the river system in the Midwest. Therefore, much of the streambank derived-P may not have been correctly attributed.
He also points out that both legacy and residual phosphorus – a distinction he recently proposed in Environment Science & Technology – should be considered when evaluating the source for phosphorus in the streams and rivers. Lag effects of P losses from legacy and residual P sources can decouple P losses measured today from contemporary fertilizer usage. A current ASC project on this topic is funded by Illinois NREC, and recently reviewed by Margenot at the annual Illinois NREC meeting.