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Injecting manure into soil reduces estrogen runoff loads

Several Penn State studies have shown the potential benefits of shallow disk injection (shown here) for reducing phosphorus and nitrate transport in surface runoff. The inset photo shows injectors.
Several Penn State studies have shown the potential benefits of shallow disk injection (shown above) for reducing phosphorus and nitrate transport in surface runoff. The inset photo shows injectors.

A new study 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.

Conducted by researchers in Penn State’s College of Agricultural Sciences, the study 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 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.

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.

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The researchers used manure from dairy cattle, but estrogens are a component in the waste stream of not only dairy, but all livestock and humans. Although this study focused on ubiquitous natural estrogens, synthetic estrogens also can affect water quality, including ethinylestradiol, the active ingredient in birth control pills or synthetic androgens such as trenbolone, often given as ear implants to beef cattle.

“The method of animal manure application can influence the availability of nutrients and estrogens to runoff water,” said lead researcher Odette Mina, a recent doctoral degree graduate. “Several studies have shown the potential benefits of shallow disk injection for reducing phosphorus and nitrate transport in surface runoff compared to surface broadcasting. Our research demonstrated significantly reduced estrogen transport in runoff from shallow disk injection plots relative to surface broadcast plots.”

This research took place at the Kepler Farm plots located at the Russell E. Larson Agricultural Research Center in Rock Springs, near Penn State’s University Park campus. The site consists of 12 hydrologically isolated plots which direct surface runoff from each plot downslope through PVC pipes to huts near the plots. The huts are equipped with tipping buckets that measure the surface runoff flowrate and allow researchers to collect flow-weighted samples to analyze the nutrients and contaminants in the runoff.

Researchers saw a striking difference between estrogen loads and concentrations in runoff following precipitation events, Mina pointed out. When manure was injected into the soil, estrogens were far less likely to leave the field.

A rainfall event that occurred two days after manure was applied caused a really big movement of estrogens, carbon and phosphorus from the surface-broadcast plots, said Mina.

“But that same event was not enough to even trigger runoff from the plots that had undergone shallow disk injection of manure. That first flush washed off really high concentrations of phosphorus and estrogens relative to the entire rest of the study, but there was nothing from the shallow disk injection plots,” said Mina.

More research on the impacts of manure injection is planned. In a follow-on study, Gall said she wants to be sure keeping estrogens out of surface runoff doesn’t result in the contaminants leaching into groundwater.

“There potentially could be some trade-offs with groundwater quality, so by doing the shallow disk injection you could be promoting more nutrient and estrogen loss into groundwater, perhaps causing localized concerns for people pulling their water from wells,” Gall said.

To read the original article, visit: news.psu.edu

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  1. As a former Senior Environmental Officer(Engineering) for the Ontario Ministry of the Environment I was the only Engineer in my class to get actively involved field work rather than sitting behind a desk all day. It soon became apparent that Agricultural operations were creating the greatest harm to the environment. The disposal of animal manure in accordance with normal farming practices was exempt from the environmental protection act. In order to control manure runoff It would be necessary to change normal farming practices. I attended agricultural equipment shows in the early 80’s and looked at direct injection equipment for manure spreading. It was readily available along with chemical spray equipment that eliminated spray drift. I tried to get the use of this equipment to be considered normal farming practice but left the government to pioneer the environmental audit field which I hoped would extend to agricultural operations. It is too bad the ministry of the environment failed to continue my work on direct injection and still allows direct field spreading just before major rain events with no attempt to plow the manure in. I witnessed this first hand today near lake simcoe and its tributaries. In fact the tractors were carrying the manure on their wheels on to a main paved roadway during rain and my sports car is now covered in manure. I appreciate the work that has been done in this study but it should have been done in the 80’s.

  2. As a former Senior Environmental Officer (Engineering) for the regions of York and Durham and Simcoe County I looked at this technology in the early 80’s. I attended an Agricultural Equipment Show in Toronto at that time and the Direct injection Equipment was readily available as well as chemical spraying equipment that eliminated spray drift. It is sad to see the Ontario Ministry of the Environment still allowing surface spreading of manure during rain events before cultivating the manure into the soil. I actually witnessed this today. The tractors were using a main roadway and carrying the manure from the fields onto the roadway on their tires. My sports car is now covered in manure spray. I applaud this study but this equipment should have been put into use in the 80’s. I do not think ground water will be affected as the manure is only injected at a shallow depth. If cultivated in after surface spreading the affect would be the same.


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