Well, good. That 3.7 dS/m sure sounds a whole lot more like what I would expect from a green waste compost. I'll say it again: I think there was a mix up somewhere. 3.7 is still a little high for some plants but isn't going to kill anything. A few thorough irrigations and/or rain events should get it down below 3.0 in the root zone, which is safe for just about anything. Just be sure to monitor moisture carefully all the way through the root zone to ensure that it is allowed to dry slightly between irrigations. If it is already saturated when you apply more water, the effects of leaching will be impeded. Prolonged saturated conditions can also lead to an anaerobic environment as well as favor the pathogens responsible for root and crown diseases. With that in mind, the boron may be in less soluble forms which, as you stated, aren't available to plants. The key phrase when you talk to the lab is to ask for the boron value in "parts per million in extract". They may charge you extra for that number since it wasn't part of the package you ordered. However, if they ran a saturation extract (which is likely how they got their salinity and sodium values) they probably have the boron number and others on hand but they only report what you've paid for. I wouldn't sweat the pH too much either. Plant response is going to vary depending on species and variety. Plants sensitive to alkaline soil conditions will probably be yellow, particularly on younger growth and they may not grow very fast. Depending on how sensitive, growth can end up severely stunted and yield can be affected. However, 8.6 won't kill anything. And as you stated earlier (Good job on your homework!) the alkalinity can help tie up any boron that may otherwise be soluble. Another thing to consideration is that the pH of compost will usually shift towards neutral over time. I would guess that a lot of your nitrogen is still in the ammoniacal form (NH4). As that converts to nitrate (NO3)the pH should decrease, if that is indeed the case. However, high pH in a finished compost is not unheard of. If it is fully composted, and the pH is still that high, an addition of sulfur may be warranted. Sure, lots of plants can handle an 8.6 but just about anything would prefer a lower pH. (And their is also that soluble boron to consider) I'm glad the growth trial sounds like its going well so far. You'll still want to keep an eye on it for a while though. Often the symptoms of boron toxicity take a while to show up because boron accumulates in the tissue over time. But let's wait and see if you can get that extract value for boron before we draw any real conclusions. However, the growth trial and the salinity value are very encouraging.

In a home garden, and even on a farm, philosophically, it can be stated that simplicity is superior in almost every way. In other words, the more variables one introduces into the gardening equation, the more effort you create for yourself in the near future, with no real, measureable net gain. Having to apply greater nitrogen levels will, in addition, create a host of new potential complications, such as disease pressures your garden wouldn't otherwise be exposed to, and greater irrigation needs. Precision becomes more paramount in your gardening protocol, something even a very experienced gardener naturally learns to circumvent through the experience of hard knocks. So, philosophically, it can be said that it is best to minimize those type of learning experiences, as a whole. Best wishes. M

As a keen composter, I have issues with a compost method that uses electricity to do something that can happen naturally outside - why add to your carbon footprint, while trying to reduce it? Be aware that you can only produce compost in two weeks by 'batch' composting - ie you load up your composter with the right proportions of greens and browns and then let it do its thing, in the right conditions. You cannot keep adding to it until its finished, emptied and you're ready to start again. If you don't want to go outside, consider a wormery. Alternatively, just do what most composters do: keep a plastic bucket with a lid under the sink and empty it regularly into your outside pile. You don't have to shovel or turn compost: Compost Will Happen: you only need to fuss with it if you want it quicker. FWIW, my mother has always (since a teen in WW2) keep a scrap pot in the corner of her sink, which was emptied into the 'pile' outside daily. Garbage disposals are a novelty where I come from. Not having one has never been a hardship.

Thanks, everyone!! I think I will go with the green bin approach, since I worry that the perlite will just blow around and be a bother around the building. It already happens in my pots! Funny how it seems to end up on top, I guess bc it's lighter. Since the balcony gets so hot, I think the soil just gets baked into oblivion and I don't feel comfortable reusing it in my pots, no matter what else I put in. Just out of curiosity... how does it get composted by the big composting outfits? Is it that it gets put in with such a large amount of actual compost in the making, that the fact that the structure has been ruined gets so diluted that it doesn't matter anymore? Maybe it somehow reclumpifies or something?