Hello, everyone. I have a question regarding nitrogen fixing by certain soil components, and how it influences fertilization. I am trying to develop a better soil for my potted maples, and have found as a component (in addition to pine bark pieces, and perlite) a mix of composted bark, wood chaff, cocofiber and cocopeat. I chose the product to avoid peat, and because it uses very little initial fertilization - it's a mix for growers, and not especially meant for the 'end user'. I talked to a couple of representatives from the firm and two growers who use that particular product. The reps in particular mentioned that I needed to take into account the nitrogen deficit that occurs with the coco products contained. This, plus the low initial fertilization seemed fine to me, since I was warned in other threads about not using much fertilization in the first place. Now since they were so adamant about this, I'd like to find out what I need to do, or worry about, if anything. I plan to fertilize these maples that are about 5-7 years old once the leaves are about 70% out, in May and only then. I am thinking about experimenting with organic fertilizers on some, non organic granular on others. Do I need to add anything when I repot now because of this issue? As I said, I was not planning to do this. If I need to add a little more nitrogen to compensate later, how much? The product has an initial low organic fertilization, like this : N 50 - 110 mg / l P 30 - 70 mg / l K 460 - 700 mg / l PH: 6-6.8 Salt: 0.4-0.8g/l Thanks for any input. schusch PS: I know these indications are in grams and liters, but since recalculating would imply me knowing how these indications are listed in North America, I thought I'd leave it as is.