September 18, 2011

Letter to the Editor: More data on Dilmun Hill

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To the Editor:

Re: “Students Get Hands Dirty at Dilmun Hill and MacDaniel’s Nut Grove,” Science, Sept. 14

Last Wednesday, a peer review of Dilmun Hill and the MacDaniel’s Nut Grove (separately functioning facilities operating in close proximity to one another) was published in the science section of The Sun. This article focused particularly on the soil contamination research projects at the student farm. On behalf of Dilmun Hill, I would like to briefly describe the projects we have implemented to address the soil contamination issues at our site.

About half of the seven acres of land that is now managed by Dilmun Hill used to be managed by the Cornell Orchards. From the late 1800s until the 1950s, it was common practice for orchards to spray a lead-arsenate based pesticide on apple trees. Students began farming at this site 40 years later in 1996. While students involved with the farm have made strides to address Dilmun’s problematic land-use history since at least 2000, beginning in 2007, staff members and students involved with Dilmun took soil samples of the entire farm and created maps that show “hot spots” of lead and arsenic contamination at the farm. The contaminated land was put into cover crop (grass and clover), and two projects were established to deal with the contamination. One is a permaculture design plot, which grows mostly ornamental plants, and the other is the Best Management Practices (BMP) project, which is exploring low-cost management strategies for safely growing annual vegetable crops. The BMP project is specifically investigating the efficacy of raised beds for growing annual vegetables on a contaminated site. The purpose of the raised beds is to keep plant roots and fruits from having contact with the native contaminated soil. The primary pathways for human exposure to soil-borne lead and arsenic are inhalation of soil dust and ingestion of soil particles, so it is important to limit human and plant exposure to the native contaminated soil as much as possible. The BMP project is in its second season of research at the farm. Last summer, all of the tissues from vegetables grown in the BMP raised beds that were sampled tested well under our levels of concern for lead and arsenic. Test results for this season have not been received yet, but if the results are the same, the Market Garden at Dilmun Hill will expand to include those raised beds. Vegetables grown in those raised beds will be tested every year to insure that our management strategy continues to be safe.

The Market Garden is the original and most visible project on the farm. Students are hired every season to manage approximately 1.5 acres of fruits and vegetables for sale to Cornell-based markets. This 1.5-acre plot, called “Tortilla Flats,” is located on uncontaminated land.  We know this land is uncontaminated based on documentation of the land-use history, and from the “hot spot” maps described in the above paragraph.  At this time, only produce grown in the Market Garden is sold at our twice-weekly farm stands and to Manndible Café. Vegetables grown in the BMP raised beds and edibles grown in the Growing Mosaic permacutlure garden are for research purposes only. Non-edible, ornamental flower bouquets from the Growing Mosaic garden are sold at farm stands and for special events.

Over the past five years, students, staff and faculty working at Dilmun Hill have devoted their time and research to ensuring that the student farm remains to be a safe place to learn and work. The implementation of the Best Management Practices project and the Growing Mosaic Garden have expanded land-use possibilities at Dilmun and exposed students to important issues in agriculture. Particularly as interest in urban agriculture grows, issues related to soil contamination will gain increasing relevance.

Elizabeth Goodwin ’12