UNIVERSITY PARK, Pa. — With water quality in the Chesapeake Bay suffering from excess nutrients and fish populations in rivers such as the Susquehanna experiencing gender skewing and other reproductive abnormalities, understanding how to minimize runoff of both nutrients and endocrine-disrupting compounds from farm fields after manure applications is a critical objective for agriculture.
A new study by researchers in Penn State's College of Agricultural Sciences shows that applying manure to crop fields by means of shallow disk injection into the soil rather than traditional surface broadcast significantly reduces estrogens in surface runoff. This finding suggests that manure-application methods can be used to control the mobilization potential of estrogens and points to opportunities for protecting downstream water quality.
The research, published this month in Agriculture, Ecosystems and Environment, also investigated how manure-application methods affected runoff of total dissolved phosphorus and dissolved organic carbon. Researchers found that transport rates of those nutrients, to a lesser degree, also were lower after manure injection than after surface broadcast.
Earlier findings from the study, which was conducted from October 2014 through the summer of 2015, were published in the Journal of Environmental Quality in November 2016. The research sampled 10 surface runoff events from 12 research plots — six with each application method — after the fall application of manure.
The application of livestock manure to agricultural fields provides essential nutrients for crops and adds organic matter to soils. However, manure also introduces emerging contaminants to the environment, including the natural estrogens 17 alpha-estradiol, 17 beta-estradiol, estrone and estriol, according to Heather Gall, assistant professor of agricultural and biological engineering.