B A R;2469935 said:
Thanxx Sue. My post wasn't a plug for PJ's Soil mix but more for what I think about when folks say they don't need to adjust they're PH levels. I may be wrong but if this chart is correct it's the only explanation in my opinion & if so that could mislead a lot of growers with very high or low PH levels into thinking "that since so & so doesn't have to adjust using such & such I don't have to either". No dis-respect to Organics.
I believe I can add something here that will clear up the confusion.
As someone who hasn't checked pH, let alone adjusted it, for the last 3-4 years now, and as someone who understands a bit about soils, here are the facts. This isn't my opinion....these are facts and I can back them up.
1. charts that show nutrient availability at different soil pH like the one above are based on
NPK, sterile soil, corporate salt farming science. (yes it is science.) In sterile soil, barring other factors (see number 2 below) these charts are accurate and correct.
2. The "other factors" that are often forgotten is that soil itself is a powerful buffer. In a properly designed soil, like almost every commercial potting soil out there, the soil is pH balanced, usually with Dolomite and/or limestone. What this means is that even if you water with pH 3....the buffering ability of the soil will bring the pH back into range. It takes many gallons of water....hundreds of gallons....to alter the pH of a decent soil. So, most soil growers do not need to pH at all, even if they're using hydro nutes in the soil.
3. When talking about a biologically active soil, where root systems are colonized and healthy, pH becomes even more meaningless because the "critters" in the soil excrete humic and fulvic acids all the time in order to release minerals from the soil and feed the plant. They make subtle pH changes as needed, depending on what they're trying to "eat." The biota adjust pH automatically, in real-time, and they don't use phosphoric acid or sodium hydroxide to do it! They use humic and fulvic acid......24/7.
So, to summarize, there is no good reason to pH water in a decent soil grow.
However, there are two good reasons to NOT adjust pH in a decent soil grow:
excess phosphorus from pH down....excess sodium and/or potassium from pH up.....both of these will hurt CEC and produce less healthy plants.
Hydro is completely different! There is no biota and no buffers, so getting the pH right is critical.