Pee for the Peonies
Join us on Saturday June 1 and Sunday June 2, 2024, starting at 9 am each day!
We will have experts present from University of Michigan, University of Buffalo, PHLUSH!, and Vermont’s Rich Earth Institute. There are opportunities to participate in our research and to also learn about Rich Earth’s Urine My Garden program!
In 2021 and 2022, we applied a treated, sanitized urine-derived fertilizer (UDF) from Brattleboro, VT to peony beds 24 & 26 (control beds: 25 & 27). Nutrients were applied in accordance with soil tests. In 2023 we did not fertilize. In 2024, we fertilized with UDF from our urine separation system on U-M’s north campus and created a 0.2:0.4:0.4 NPK product. We applied to one of two peony pairs in all four beds (24, 25, 26, 27).
While the fertilizer needs for peonies are modest, our primary goal is to direct attention to how nutrients flow through our community, regenerative food-nutrient cycles, and how UDF can be part of a more sustainable future.
“Pee for the Peonies” is a partnership between University of Michigan researchers in the department of Civil and Environmental Engineering and the Matthaei Botanical Gardens and Nichols Arboretum.
Fertilizing the Peonies
Lucinda Li (right) and Harrison Suchyta (left) apply UDF to peonies in 2021.
Creating a Struvite Fertilizer
A struvite precipitator was used in order to create two fertilizers. The first is a solid fertilizer that is rich in phosphorus, and the second is a liquid fertilizer that contains mainly nitrogen and phosphorus.
These fertilizers are able to be harvested since the precipitator mixes the nutrients together to create both products. After adding some chemicals (magnesium chloride), the mixing allows for virtually all of the phosphorus to combine with nitrogen and magnesium to make a solid fertilizer powder that is then filtered out.
The remaining liquid urine is rich in nitrogen and potassium. This liquid is then pasteurized and run through activated carbon to remove pharmaceutical material. Both fertilizers are then able to be applied to plants.
After fertilizer application in April, our team will sample for qualitative comparisons between fertilized and unfertilized peonies. We will compare soil composition, size of peonies, length of blooms, and appearance of any harmful discolorations on the peonies.