Winter manure management for water quality
Manure offers benefits beyond synthetic fertilizers by increasing soil organic carbon and soil water holding capacity, decreasing soil bulk density, and spurring microbial activity for better nutrient uptake by plants. Despite the benefits, there are some adverse effects to manure applications, most of which are only studied during the growing season. Winter manure applications require more research, especially with the increasingly unstable seasonality of freeze-thaw events and spring snowmelt due to climate change. Minnesota does not ban winter manure applications for small farms or for larger farms that only apply solid manure, making research on this topic critical. My research looks at 1) Whether the timing of winter manure application affects the nutrient content and loading in snowmelt runoff and 2) Whether the location of manure within the snowpack influences nutrient dynamics and nutrient loss patterns in snowmelt. Research on this topic can better inform existing water quality and manure best management practices.
Extreme heat events and public health in Minnesota urban areas
Extreme heat is often overlooked as a public health concern in Minnesota, where intraseasonal summer variability limits acclimatization to oppressive heat conditions. Specific categories of synoptic-scale air masses are linked to summer excess mortality, particularly within urban heat islands. In the past 75 summers, Minnesota urban areas have experienced narrowing diurnal ranges and decreased nighttime cooling, while hot and humid air masses have increased in frequency at the expense of cooler and drier ones. In this talk I will discuss the influence of air mass frequency and character on heat-related health outcomes, and how downscaled climate projections for mid and late 21st-century Minnesota can be utilized to evaluate future synoptic trends and their associated risks.
Developing best management practices for integrating liquid manure and cover crops
Manure is a source of both micro and macronutrients and may improve soil physical and biological properties thus enhancing soil health. However, there still are avenues for nutrient loss that may impair air and water quality. Cover crops (CC) may effectively take up excess nutrients and potentially contribute to improved soil health. A small plot study was initiated at the University of Minnesota Southern Research and Education Center to measure the effects that integrating CC and manure have on soil health, nutrient cycling, and agronomic productivity. Various CC species and seeding methods were evaluated along with various nutrient sources and timing of application. Liquid swine manure was injected through sweeps to minimize soil disturbance during early and late fall or commercial fertilizer was applied in spring. Preliminary yield data show that later application of manure significantly improved grain yield while the inclusion of cereal rye, whether as a monoculture or mixture, reduced grain yield. Although there was a yield reduction by CC, alternative ecosystem services may offset this.