Have you thought about brewing your own worm teas for your garden? Do you have your own fresh worm castings for brewing with? Fresh castings will have a lot more life then store bought castings. There are a lot of good worm tea recipes out there but most are for brewing a bacteria brew with molasses but you can also brew a fungal brew with more carbs and proteins as a feeding base to grow your microbes. Things like yucca and seaweed extracts and rock dust is also a great additive for a boost and if in flowering periods guano really makes a bang. I also do a casting insect frass mix. If you have never tried frass in your brews it is a great additive or a great soil mixture in general for the chitin and microbes it also produces. I make different brews for different uses. If I am doing new sprouts I just use a very basic casting tea but if I am doing flowering especially in DWC or hydro I use a much more potent mixture.
Aerated tea is something everyone should make and use. We brew with a list of different meals and additives for different results with things from sea 90, alfalfa meal, humic acid, guano, frass, fresh castings from the bin, seaweed and yucca extract, and have even tried things like adding urea, blood meal and fish bone meal into drenches for my plants.
Fresh castings ready to be brewed.
Cheap soil test are not the best but they will ball park where you are at. What they won't do is tell you about your microbes in your castings or compost. For that you will need more detailed testing then your average NPK.
All you need to do is find out what your castings or potting soils are lacking and get the proper soil amendments to add what you are lacking. You also need to find out what your plants need depending on where they are in the growing or flowering phases and how you would like your brews to effect your plants. My soil brews are usually not as strong since I also top feed my brew mixture back to my soil plants but my DWC or hydroponic grows are going to be much more potent of a brew. I have also gotten more into studying fungal brews over bacterial brews for the long term effects in my pastures and padlocks where I keep my livestock.
Teas added to my soil, if you can call it that, is very important since my ground here is mainly sand and since it dries out for several months of the year there is not much microbial life in it. My teas allow me to add back a lot of the missing microbes. We soak corn and sunflowers along with other things like barley or rye and walk threw the padlocks tossing a few handfuls here and there. Next I use a backpack sprayer to spray my tea mixtures in my padlocks so by time my livestock makes it back around I will have nice heavy growth for them to feed on.
Even a simple bacterial worm tea made form castings, molasses and humic acid brewed in a 5 gal bucket with an air stone is a great boost for your plants. You can always start with adding a simple kelp or seaweed to it and see how it changes your production and then take another step. Always document your results because you may not remember what was added 5 brews ago to get that great harvest much less the amounts added. I always add it in % of the mixture since I may do 10 gals now but could step up to a larger brewer later on and if you have your recipes in % of the mixture it is easier to change it to different size brews larger or smaller so when I write mine out if I was doing a 15 cup recipe it would look something like -
33% castings - 5 cups
33% frass - 5 cups
10% kelp meal - 1.5 cups etc. etc.
I hope you found this information useful and if anyone has anything to add or different ingredients they use I would love to hear about it.