Dirt losing the majority of it's nutrients after a year?
I have three dirt tanks setup, and currently I'm putting together a 46 gallon bowfront I plan on dirting as well. I picked up a new bag of MGOPM yesterday, and noticed it says right on the bag "feeds plants continously for six months. Well, what happens after that period of time? Or even a year? I know Diana Walstad doesnt believe the dirt needs replenishing for many years, but I'm beginning to think otherwise. What are the thoughts on this? Do we need to subsidize the nutrients after awhile to sustain the plants? Use root tabs?