ROOTED IN RESEARCH
BUFFER STRIPS: HOW WELL DO THEY REDUCE NUTRIENT AND SEDIMENT LOADING AND DOES THE SPECIES COMPOSITION MATTER? By Cale A. Bigelow, PhD Welcome back to Rooted in Research, where we take a deep dive into timely and topical turf research. It’s been a few issues since I have had the chance to share some turf research findings, but the column has been in good hands with my trusted colleague and “The King of Rings,” Dr. Mike Fidanza, who kept everyone up to date on all things turfgrass. For this installment I wanted to dig into some more soil science research and the efforts of my colleagues to develop best management practices that minimize sediment and nutrient loss from managed turf systems. For this article, I am highlighting some of the important ecological work that was conducted by Dr. Kurt Steinke under the direction of Dr. Wayne Kussow and Dr. John Stier at The University of Wisconsin to evaluate various buffer strip systems for their ability to filter runoff water.
The Problem Back in the early 2000s, the subject of nutrient enrichment of streams, rivers, and lakes was quite the legislative hotbutton issue (as it still is today). Personally, I can’t imagine anyone caring for the turfgrass and the environment that does not want to preserve and protect water quality but there are policymakers that might disagree. Thus, across the United States, a number of states put in place a variety of ordinances and laws intended to reduce nutrient enrichment from “the built environment” including turfgrasses. Further, federal mandates to decrease nutrient pollution (e.g., nitrogen (N) and phosphorus (P)) have been aimed at reducing P movement into surface waters and N movement into groundwater for many years. Although P normally binds tightly to soil particles it only takes a very small quantity of this nutrient to cause 34
nutrient enrichment in freshwater lakes and streams. Under the right environmental conditions nutrient enrichment eventually leads to eutrophication where water oxygen levels decrease which in turn impair the ability of fish and other marine life to thrive and survive. The problem is that the exact sources of P that may contribute to eutrophication are unclear, but excess phosphate fertilizers have been implicated, and since P is tightly adsorbed to soil particles, any movement of bare soil may also contribute to nutrient enrichment. With regard to N and leaching, excess application and/or downward movement can result in contaminated drinking water supplies. This is especially important to avoid where a community is reliant on well water supplies. Regardless, we still come back to one of the fundamental lessons in managing turfgrass, “employ cultural practices that promote a dense, healthy turf.” This simple rule of thumb allows for maximum retention of precipitation and irrigation as well as minimizing any sediment/nutrient movement. With this in mind, I can understand why policymakers in states like Wisconsin were acutely interested in doing everything they could to protect water quality, including suggestions or requirements for buffer strips adjacent to any body of water. Unfortunately for the turfgrass industry, at the time there was not a whole lot of research data that documented and demonstrated differences in the possible quantity of nutrient and sediment loss coming from managed areas like turfgrass. There was abundant information from many traditional production agricultural systems but little information for how things might happen in a built environment like a neighborhood that contains hardscape (e.g., asphalt, concrete, etc.) and turfgrass. Further, there was a mindset TPI Turf News September/October 2021
