I started to make weekly pH measurements of 3 types of applications using 6oz drinking cups containers.

1.) 1 tsp Bonemeal/Liter

2.) 1 tsp Dolomitic Limestone and 1tsp Bonemeal/ Liter

3.) No Limestone

I was interested if other's have made/or monitored pH over time with other growing medium, versus different initial application amounts.

Update Week1

1.) pH 5.4

2.) pH 6.5

3.) pH 4.3

It appears as Bonemeal 20% Ca has the same effect as Dolomitic Limestone

Update Week1

1.) bonemeal only at pH 5.4

2.) bonemeal and dolomite at pH 6.5

3.) No Limestone at pH 4.3 control

It appears as Bonemeal 15-20% Ca has about the same liming effect as Dolomitic Limestone. Added a 4th mix to monitor of 1 tsp Basalt Rockdust/ Liter will wait a week to start measurements.

Week 2 Measurements Summary

Soil Mix pH Tests 50/50 Peat/Perlite (water pH approx 7.2, irrigated with the surrounding planted containers)

#0 No Limestone

#1 1tsp Bonemeal/Liter

#2 1tsp Bonemeal, 1 tsp Dolomite/Liter

#3 1 tsp Basalt Rock Powder/Liter

pH Meausurements

Mix,Week1, Week2

#0, 4.3, 4.4

#1 , 5.4, 6.1

#2, 6.5, 7.5

#3, 4.1 , 5.5

I use ProMix. I only cared about PH when I first started lol.

The measurements are some shared personal tests for pH effects of different amendments used. I usually mix my own growing mediums, some are pH critical. As far as the number of measurements, just looking for a point of stabilization ( usually 3 to 4 weeks). Also many measurements over time, gives a basic release rate data of the Limestone, or other rock minerals used. The Limestone has a limited lifespan in the mixes( 6 mo to a year depending on particle sizes). The initial pH from the Bag is usually different, than the actual final pH of the mix.

Pro Mix Article http://www.pthorticulture.com/en/training-center/low-ph-of-fresh-growing-media/

Note: Used Pour Thru Method, article indicates 2:1 Saturation gives more actual results.

I also found that the initial pH 50/50 mix of Peat/Vermiculite was pH 5.5 compared to pH 4.1 to 4.3 of the 50/50 Peat/Perlite Mix. Another benefit of long term testing, is checking how your Fertilizer is affecting the pH of the medium. I also have used Pro Mix HP which is just a 2:1 Sphagnum Peatmoss: Perlite Mix (Pro Mix is an excellent mix with good WHC, and AHC parameters). One can add extra perlite, and Redwood shavings to lower WHC and increase AHC as desired.

Dale - Even though we're using different mixes, I'm still interested in seeing your results. As long as you don't find it too much effort to continue in posting your results here.

Can't argue with PTHorticulture that pH checks are helpful and good to know how things are shifting over time.

ewwmayo- No Problem with effort involved. I needed to do this any way. I was surprised how far off many of the soil mix recipes are. Once all the different admendments are added. Measurements can be applied to Bark Mixes as 5-1-1 or other ratios. Peat Moss and Bark intial pH's can vary lot to lot also. I use Bonemeal and Rock Powders, such was interested in any modifications needed for Limestone amounts added.