The effects of soil aeration prior to dairy manure application on edge-of-field hydrology and nutrient fluxes in cold climate hayland agroecosystems

Abstract

Soil aeration is increasingly being used on haylands in the northeastern United States as a water quality best management practice to decrease runoff volumes and flow rates, and the associated export of the nutrients nitrogen (N) and phosphorus (P). However, there is a lack of data on the effects of soil aeration on field-scale hydrologic and nutrient fluxes in cold-climate regions. The objective of this study was to evaluate the effects of soil aeration prior to dairy manure application on edge-of-field hydrology, water quality, and P fluxes in haylands in Vermont, United States, during both precipitation and snowmelt-induced runoff events. Edge-of-field water quality monitoring techniques were used to continuously measure the losses of surface runoff and the associated export of sediment and nutrients year-round from 2012 to 2018. Additionally, passive-capillary lysimeter systems were used to measure the subsurface losses of P. Aeration reduced total suspended solids, total P, total N, and total dissolved N mean runoff-event concentrations by 22%, 32%, 25%, and 34%, respectively. Event mean surface runoff volume increased by 16% due to aeration, resulting in no significant reductions in nutrient load exports during nonwinter runoff events. However, total P and total dissolved P loads were significantly reduced during large winter thaw events, often occurring months after aeration took place. Potential increases in surface and subsurface hydrologic flows that accompany nutrient export reductions should be considered before implementation of soil aeration on haylands with high runoff producing soils in cold climate regions.