Subsurface injection of manure reduces estrogen transport
Livestock production is increasingly tied to water quality concerns, in part due to the management of manure on farms. While strong emphasis has been placed on how manure application methods affect nutrient transport, the effects on estrogen transport are largely unknown.
In the 45th issue of the Journal of Environmental Quality, researchers report on a nine-month field study in central Pennsylvania to compare estrogen concentrations and loads leaving fields that had received dairy manure via shallow disk injection versus surface broadcast methods.
The team found that shallow disk injection reduced estrogen loads over the study period by an average of two orders of magnitude compared to surface broadcast. Additionally, the timing of the largest loads from the two application methods differed, with the first flush event being the most important for estrogens leaving the surface broadcast fields, whereas a hail event 6 months after application triggered the largest loads leaving the shallow disk injection fields.
Although shallow disk injection is not commonly used in the eastern United States, our results show that shallow disk injection has the potential to reduce the loads of estrogens exported in surface runoff after dairy manure application and the potential threat that endocrine disrupting compounds may pose to aquatic organisms.