Reducing Phosphorus Transport: An Overview of Best Management Practices

Abstract

With the problem of excess P in surface waters established and various non-point sources identified in Chap. 1, this chapter moves deeper into the mechanisms of P transport from terrestrial sources to surface waters. Specifically, P transport is split up into two main categories of sources (incidental and legacy), and broadly described as two main forms in drainage waters: particulate P and dissolved P. The two P forms are especially critical since they behave differently with regard to aquatic bioavailability and the means in which each form is transported. These inherent differences translate to differences in the types of BMPs that can be utilized for reducing transport of each of the P forms, potency of each P form for causing eutrophication, and the temporal aspect of P losses. This chapter focuses more on legacy P sources rather than incidental P losses because of the greater difficulty in controlling the latter. Phosphorus management in the context of legacy P sources is presented as a system in three main categories: (1) prevention of legacy P formation, (2) containment of legacy P, and (3) remediation of legacy P. While some conventional BMPs are effective at reducing particulate P and few are effective at partially containing dissolved transport from legacy P sources, none will remediate dissolved P losses from legacy P sources in the short-term. Because of the unique temporal aspect of legacy P and dissolved P transport, there is a need to utilize both long-term and short-term remediation for reducing dissolved P transport. The long-term remediation of legacy P sources is achieved through soil P drawdown with plants, and the dissolved P losses that occur in the short-term during that slow process can be remediated with P removal structures.