Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants BioChar for nutrient control

Hello PB gang. Just wanted to share a project I have just done. Very brief review: I have a 2.5 acre pond in central Iowa, ~ 40 years old, highly eutrophic. I have over 60 acres of ag run-off feeding my pond through two inlet fingers. One is long and lined with grass. The other has tile pipe draining into a mostly silted in catch pond, which then drains into the main pond. As many pond owners have discovered, uncontrolled nutrients lead to problems. The primary one for us is FA (and sometimes duck weed). We use pond dye frequently, we have aeration system running (for past 9 years) and use liquid and granular copper frequently. We've also raked out mountains of FA mats over the years. I've also dabbled in trying to tweak the emergent and shallow water edge plants to try and trap and consume nutrients, with variable to minimal success. So in an effort to address the nutrients in a new way, I found some articles on using BioChar to lock up nutrients in highly eutrophic bodies of water (i.e. old ponds). I found out that Iowa State University founded a research group on the use of BioChar as a carbon sync. But for me, the interesting additional benefit is for ponds and nutrient management. So, I decided to purchase some bulk biochar granules and then put it to work. I was able to go and pick up 1 one cubic yard bag (big nylon bag) with my own trailer, which saved me shipping costs. This amount is about 300 lbs. I also purchased a role of unfilled 8 inch filtration sock, which is what you often see used to control sediment run off in newly planted drainage ditches by your DOT or on a construction site. I then filled some custom lengths of sediment sock with biochar granules. I then wrapped these biochar filled 'logs' around the inlet pipe that feeds my main pond from the silt pond, in stacked tiers. The idea is to have the inflowing run off pass through the filter socks with biochar, to trap the nutrients before they enter the pond. I'm including pictures, as that may be hard to visualize. I haven't collected water samples to monitor, but it's on the list. I have only completed the initial set of filter logs so far, and have 3/4 of my bag of biochar granules left. I plan to place a stack of logs in front of the exit pipe feeding the main pond (basically the opposite end of the pipe I've already filtered). I also plan to spread some biochar granules along the margins of my pond, directly into the sediment. The research group at ISU has already done this at test sites in Minnesota with good success. Biochar is also non toxic to fish/plants/pond life. I'll let you know how it goes.

Inlet pipe, before:



view of both inlet pipes, silt pond of right (yellow caged top) and main pond on left (white PVC pipe)