I am a complete and udder (cows roaming around in my brain!) utter newbie to the world of hydroponics so when I toured a hydroponics facility in Western New York this week I was like a kid in a candy store: all new stuff to learn and touch and taste (including the yummiest arugula I have ever tasted!).
My naïve assumption was that the biggest opportunity for biochar in the greenhouse world might be as a growing medium. It still might be, but I learned that the ideal pH for plants in this particular greenhouse is between 5.5 – 5.8 which is lower than the average pH for most chars so we’ll have to figure out a process for lowering it. However the farm manager actually pointed out a much more interesting opportunity for biochar within the context of hydroponics that has to do with the greenhouse effluent. Apparently this stuff is loaded with phosphorous and nitrates. In excess these nutrients can harm local ecosystems and even lead to eutrophication (which can turn lovely blue water into nasty green algae laden, oxygen starved cesspools).
Now I’m thinking that we need to first use the biochar as a filtration medium for the effluent. Not only would this mitigate the damage to the local ecosystems but most likely the biochar will adsorb the nutrients and effectively charge the biochar with valuable macronutrients. Then the grower will probably have a great little fertilizer that can be used in the hoop houses where they grow directly in the soil.