I'm growing outside in 25-gallon containers and need a recommendation for how much dolomite lime to add to my growing media. 1 part Gardner & Bloom Potting soil 1 part perlite 1 part decomposed cow manure 1 part peat moss I use a 5-gallon bucket to measure quantities so the lime addition would be primarily for the five gallons of peat moss (mixed first, still watching Craig's list for a used cement mixer). One cup? Two?
I rarely find the need to lime my mixes, especially since your using a premix you might want to check the Ph level of the soil first usually premixes are Ph balanced already. Secondly I would mix your soil first and put it in your 25 Gallon and run water through it. By doing this you'll get a more accurate reading, then if you find it to acidic you could quantify your amounts based on the reading your recieve. HTH -Gdaddy
The G&B potting soil is pH adjusted with dolomite lime. I'm hesitant to not include lime as peat moss is acidic, running from 3.4-4.8. General gardening formulas recommend 5-10lbs of lime to each bale. I'm using it as a water retainer, not a soil amendment, with well water that consistantly tests at 7.0. My concern is the peat dropping my water down to a marginal pH.
Due to my location it's rare that I'm able to get Sunshine mixes or cocnut coir based mixes, therefore I use bales of peat moss. My Ph runs between 6.2-6.8 without lime. The soil that I did lime for a tester is causing nutrient lockout and stunted growth because the Ph stays at 7.0-7.2 Either way though, if you complete the suggested method above and get your reading, it would be better than blindly adding X amount of Dolomite and causing trouble down the road.
I tested my water, 6.96, and then a mixture of my water and peat for 5.81. Tomorrow I'll do the other components individually (curiosity) and then test the mix. I agree with you, not following logical methodology would be foolish on my part.
madodah There's a gentleman by the name of Steve Solomon who was the original founder of an heirloom seed company in Oregon called Territorial Seed Company. He sold the company years ago and went on to write a couple of books on gardening in the wet area of the Pacific Northwest. He now has a web site called Soil & Health Library which is well worth perusing. Back on track - a few years ago Steve wrote an article about mixing one's own organic fertilizer mix. You can find it by searching for 'Steve Solomon COF' (complete organic fertilizer) and there is more than one incarnation of this mix. One version says to take equal parts of dolomite lime (calcium & magnesium), gypsum (sulphur) and agriculture lime (I opt for oyster shell powder). This then is your 'lime' mix and one would apply it at the same rate as straight dolomite lime. The reasons are explained pretty well at the various sites promoting this COF. Just a thought. LD
Hmm...if you´re mixing your own peat based mix, the general rule is 3 to 4 cups per bale of peat. But if you´re using potting soil....looks like you´ve got it covered.
In looking at individual component pH factors the cow manure high pH and my well water seem to offset the peat's low pH, eliminating a lime requirement. There is lime in the potting soil but only enough to balance that component. I'll continue to monitor runoff pH and see how long the cow manure contribution lasts.