Why Study Herbicide Contamination of Compost?
Picloram, clopyralid, aminopyralid and aminocyclopyrochlor are broadleaf herbicides commonly used in pastures due to effectiveness in controlling undesirable plants and the very low toxicity for animals and fish. In fact, some of these herbicides do not require animal removal post application. The grazing animals can ingest treated leaves with no ill health effects, but may pass the herbicides through to the manure. Also see: Composting Livestock or Poultry Manure
When a complaint driven problem of damaged tomatoes and other garden crops in Vermont was traced back to a single compost provider in Chittenden County in Vermont, a series of actions and reactions commenced. Complaints were fielded and investigated by personnel from the Vermont Agency of Agriculture, Food and Markets (VT-AG) and the University of Vermont Extension (UVM-EXT). The compost provider sent samples of various components of the compost to a single laboratory and received positive results for persistent herbicides in sources of equine bedding/manure components. Subsequent interviews by the facility manager in both print and television media seemed to cast blame on Vermont equine operations for ruining Vermont gardens. Coincidentally, the composter had recently changed compost-processing methods. Initial samples sent to a separate laboratory did not support the composter’s laboratory results. Samples of feed, manure, shavings, and many other components which were shipped to several laboratories by VT-AG, resulted in extremely inconsistent and/or contradictory data between laboratories running the exact same samples.
Related: Small Farm Environmental Stewardship or Managing Manure on Horse Farms
What did we do?
Several processes were underway by several agencies in a coordinated and collaborative effort to resolve and mitigate the herbicide issues:
• Vermont Agency of Agriculture, Food and Markets was receiving and investigating complaints.
• University of Vermont Extension plant biology personnel were identifying, documenting, and sampling affected plants, as well as counseling gardeners.
• University of Vermont equine extension worked with horse owners and media to mitigate unsubstantiated claims of “horses poisoning garden plants”.
• A more thorough investigation by VT-AG involved collection of raw samples (feed, hay, shavings, manure) from 15 horse farms who utilized the compost facility to dispose of manure and bedding.
• The VT Secretary of Agriculture and the VT-AG Agri-chemical Management Section Chief were brought together with equine and compost experts attending the NE-1041 Equine Environmental Extension Research group annual meeting hosted by UVM equine extension.
• VT-AG worked with herbicide manufacturers to use high quality testing equipment and procedures to gather consistent data from samples.
What have we learned?
More extensive details of this particular case have been published in the Journal of NACAA (http://www.nacaa.com/journal/index.php?jid=201).
• The levels of persistent herbicides were low enough that they were below the acceptable limits for water, yet they still harmed sensitive garden plants.
• Nationally and locally manufactured grains tested positive for persistent herbicides; most likely due to the individual components being treated within legal limits during field production.
• Many of the laboratories were unable to provide accurate or consistent results when testing for the persistent herbicides.
• Discussions between the NE-1041 group and VT-AG resulted in a fruitful exchange of information, as well as development and delivery of pertinent information for the general public and County Agricultural Agents.
Future Plans
Several proactive activities have already been initiated and/or completed. A peer reviewed case study on all aspects of the contaminated compost has been published in the Journal of NACAA; and two episodes of Vermont’s Agricultural television show (Across the Fence) were created to educate and update the general public on the situation. A Vermont compost working group has been assembled and set goals to create potential educational materials including a horse owner pamphlet (in final editing phase), a farmer/livestock pamphlet, and press releases for the public education on challenges with persistent herbicides. The VT-AG website has a Compost FAQs page addressing the most common questions associated with compost and herbicides.
Authors
Betsy Greene, Professor/Extension Equine Specialist, University of Vermont Betsy.Greene@uvm.edu
Carey Giguere, Agrichemical Management,Vermont Agency of Agriculture
Rebecca. Bott, Extension, South Dakota State University
Krishona. Martinson, Extension, University of Minnesota
Ann Swinker, Extension, Penn State University
Additional information
• Greene, E.A., R.C. Bott, C. Giguere, K.L. Martinson, and A.W. Swinker. 2013. “Vermont Horses vs. Twisted Tomatoes: A Compost Case Study. J of NACAA. 6:1 (http://www.nacaa.com/journal/index.php?jid=201)
• Vermont Agency of Agriculture, Food and Markets Compost FAQ’s: http://agriculture.vermont.gov/node/696
• Davis, J. Dept. of Horticultural Science, NC State University. 2010. Herbicides in Manure: How Does It Get there and why Should I Care?, Proceedings 8th Annual Mid-Atlantic Nutrition Conference, Timonium, MD. pp 155-160.
• Across the Fence Television Show: An Update on Green Mountain Compost Contamination and Testing-Greene/ Gigliuere (9/14/12)
• Across the Fence Television Show: Information from NE 1041 Meetings and National Equine Specialists-Greene (9/17/12)
• Article from Minnesota Extension explaining the problem in hay and how to avoid it. The article is devoted to “ditch hay”, but the information is relevant to all hay. https://extension.umn.edu/horse-nutrition/managing-herbicides-ditch-forages
• Washington State University Web site on clopyralid carryover includes pictures of affected vegetables, research results, and the bioassay protocol http://www.puyallup.wsu.edu/soilmgmt/Clopyralid.htm
• Dow Agrosciences United Kingdom website with information on aminopyralid: http://www.manurematters.co.uk/
• CDMS Agro-chemical database with access to all the herbicide labels: http://www.cdms.net/LabelsMsds/LMDefault.aspx?t
Acknowledgements
The State University Extension Equine Specialists that make up the NE-1441: Environmental Impacts of Equine Operations, Multi-State Program. USDA.
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.


What did we do?
Future Plans
Author


The overall objective of our two year project is to assess these improved manure application practices at the farm scale through various sub-objectives. First, sedimentation efficiency is being evaluated on farms with contrasting manure management by sampling liquid storages at various depths prior to agitation. The goal is to assess natural stratification of nutrients under different bedding and water management, and to assess the practicality of sequentially pumping the thin supernatant (late Mar- early Apr) and thicker sludge (late Apr- early May). Second, improved equipment is being developed to precision deep inject slurry sludge (6 – 11% dry matter) prior to corn planting. Third, on-farm field scale trials using improved manure application equipment are assessing the agronomic and economic benefits of managing separated dairy manure fractions, compared to the traditional practice of surface broadcasted agitated raw manure.
What did we do?
What have we learned?
During the same time period environmental regulations have greatly decreased the construction of swine finishing facilities that use liquid manure handling systems that require the use of a lagoon or storage pond. In response to these economic and regulatory realities, some swine production companies are considering the use of deep pit slurry systems instead of an outdoor lagoon or storage. Benefits of the deep pit slurry system include the exclusion of rainfall, reduction in storage visibility, and conservation of valuable major plant nutrients (N, P, K) for the purpose of reducing production costs for feed grains. The objective of this presentation is to compare the fertilizer value of the manure produced from swine finishing barns that use a liquid manure handling with a treatment lagoon, and swine finishing barns that store manure below slotted floors in pits.
What did we do?
The realized value of swine manure was calculated for using lagoon water, and sludge to provide all or a portion of the N, P2O5, K2O used by corn based on typical crop needs. Only the portion of plant nutrients that met the recommendations was assigned value. No value was assigned to major plant nutrients applied in excess of plant uptake. The value was assigned based on price data obtained from USDA-ERS (2013). The prices used were $0.71/lb of N, $0.69/lb of P2O5, and $0.50/lb of K2O.
When lagoon water was applied to supply the N needs of one field, and sludge was applied to meet the P2O5 needs of another field the realized value of swine manure was $5.69 per hog-space per year. Application of lagoon water and sludge to meet the P2O5 needs of corn increased the annual value of manure to $6.64 per hog-space.