I look at testing soil as a security blanket of sorts. I have only a few grows with moderate success and the soil Im getting ready to use is a new batch thats been sitting for about 6 months with worms in it.Dank: If you have a grower that knows how to read plants and add back to the soil very slowly only what that plants have used(never happens), testing isn't as important.
It is impossible to know the soil balance without a test. Period. If you add back that 1/2 cup of amendments every couple rounds your setting yourself up for failure eventually.
You use the test as a scale in your own little micro-universe. Use the numbers, round after round, to know what levels you started at and what the nutrient draw down was. The numbers are just a scale for your observation.
Kind of like building an engine without precision measuring equipment, ie calipers, mics etc. You may get it to run, but for how long and at what % of optimum performance...
Amendments last a lot longer in the bag waiting to be mixed than in the soil being made available and then washed out the bottom of the container.
Probably too late for this mix, but wanted to caution folks to go light on Sul-Po-Mag or K-Mag. It's very high in Mg and K. The K is probably fine but the Mg can be a problem. Most container media like this have good levels of Mg already. I choose not to use it based on the soil testing I've done with my mixes, but if you did want to use it I would start at like an 1/8th of a cup per cubic ft to be safe and limit other Mg sources.
You can get the K and the Sulfur from other sources.
Probably too late for this mix, but wanted to caution folks to go light on Sul-Po-Mag or K-Mag. It's very high in Mg and K. The K is probably fine but the Mg can be a problem. Most container media like this have good levels of Mg already. I choose not to use it based on the soil testing I've done with my mixes, but if you did want to use it I would start at like an 1/8th of a cup per cubic ft to be safe and limit other Mg sources.
You can get the K and the Sulfur from other sources.
I think i will add worms eventually as well. Im wanting to get this mix started here and am really on the fence at the moment. I have the dolomite lime but am now on the fence about using it along with the sul po mag and there being too much mg. If I dont use the lime, I will then have much less calcium and I dont believe eother to be an ideal situation.
It would take another week or so to get some oyster shell flour as I have been looking locally for the past week and cannot find it.
I have some new seedlings going that will need an up pot before long and I want to get this mix composting.
I have noticed that apparent calcium deficiencies occur whenever I have an underdeveloped root system. Recently I had this happen when I rushed a few plants from veg to flower, trying to grow adult plants with juvenile root systems. No other plants showed these symptoms when allowed time to develop good roots, even though grown in the same soil, including clones of the same plant that showed the deficiency when the roots system was underdeveloped and grown under identical conditions.