Studying how conservation tillage impacts water quality

In the early 1990s, Acton Lake in southwestern Ohio had a muddy problem. Large amounts of sediment from nearby farms were entering the lake’s watershed. These sediments traveled through streams draining the landscape and were filling up the lake. So, the USDA gave local farmers incentives to change some of their farming practices.One of these practices was conservation tillage, which can reduce sediment runoff. A new study examines how the switch to conservation tillage has impacted Acton Lake over the past decades. Vanni and his colleagues found that water quality responses were different during the first decade of the study (1994-2003) compared to the next (2004-2014). They also discovered that concentrations of suspended sediment, nitrogen, and phosphorus each reacted differently.Levels of suspended sediment declined throughout the entire study period. However, the decline was much sharper in the first 10 years.Phosphorus and nitrogen levels had contrasting outcomes.“The concentration of dissolved phosphorus in the streams declined sharply during the first 10 years,” said Vanni. “But then, phosphorus levels increased over the next 10 years.”In contrast, nitrogen levels didn’t change much in the first 10 years. After that, they fell sharply.