Manure application under winter conditions: Nutrient runoff and leaching losses

Winter application of manure is commonly practiced in the northeastern and north-central U.S. Potential nutrient losses from winter-applied manure are difficult to predict due to uncertainty in weather forecasting and limited knowledge on soil-nutrient-hydrology interactions during the winter. The objective of this study was to extend the understanding of nutrient cycling and transport processes associated with manure application methods during winter months. Specifically, the influence of manure position within the snowpack on nutrient losses was examined using a laboratory approach. Dairy manure was applied either before, midway through, or upon completion of an artificial snowfall. Runoff and leachate were subsequently collected throughout a snowmelt event and rainfall simulations. Manure application prior to the snowfall increased the losses of total N and NH ₄-N in snowmelt runoff and resulted in larger losses of both N and P in runoff during the rainfall simulation. Manure application on top of the snow reduced the amount of NH ₄-N losses but increased the losses of organic N, DRP, and total P in snowmelt runoff. The results of this research show that the relative position of manure within the snowpack plays a significant role in the fate of N and P from winter-applied manure.