Grrrr! Lol - I had your whole list of questions answered and somehow lost the whole thing. I hate it when that happens! Sigh

1) Ok - the going rate for liming bark/peat-based container media is 5 lbs/ cu yd. The bulk density of prilled dolomitic lime is about 50 lbs/cu ft, so a pint weighs about .85 lbs. You need 1.9 lbs or 2.25 pints or 4.5 cups for .38 cu yd.

2) The Mg fraction in dolomite is about 125X more soluble than the Ca fraction, so it's not unusual to start seeing some sign of Mg deficiency in the second year in the same soil, but that depends on what's in the fertilizer and your water. If your fertilizer has Mg, I wouldn't worry about it unless you see something obvious on the nutritional front.

3) Lime is best incorporated where it can react with the soil and so it's available throughout the root zone. The pH of container media isn't as important as the pH of mineral soils, and fortunately, your citrus prefers a pH of somewhere around 5.0 (for container media) anyway, so I wouldn't get too nervous. If your fertilizer contains Ca & Mg (Foliage-Pro 9-3-6) ;-), you're prolly in fine shape.

4) As you can see, micronutrient uptake is actually improved at lower pH in container media (left)

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as opposed to mineral soils (right). See the Sweet spot at around 5.2?

I would lime Mel's mix based only on the volume of peat (and bark if you add any) in it. If it was me - I'd add 1 tsp of lime for every gallon of peat - less than usual because of its low bulk density compared to bark.

Take care - good to see you posting again, K.

Al

Al, I love ya. You made my night giving me these answers. When I get on one of these research kicks I head down a rabbit hole in search of new information.

1) Glad to know my math was about right. I failed chemistry in high school, and it scares me a bit. I will use your number.

2) Actually, my citrus are starting to show some signs of a Magnesium deficiency... it could be the winter, and then those freezing days we had last week, or it could be something else like my fertilization. I'm waiting for a few weeks of warm weather to see what happens. If my memory serves me, I think they looked like this last winter and our first weeks of sunshine they perked back up.

But, as you know, I *do* fertilize organically with the Dr. Earth products and my micros come from their Liquid 3-3-3 with Micros. (I'm *not*---at least not yet---using Foliage Pro. I know, bad bad student.)

The 3-3-3 apparently has: Micronized and Hydrolyzed Soy Protein, Micronized Mined and Micronutrient-dense Colloidal Soft Rock Phosphate, Naturally-mined Potassium Sulfate, Potassium-Magnesium Sulfate, Copper Sulfate, Iron Sulfate, Manganese Sulfate, Molybdic Oxide, and Zinc Sulfate. I use this weakly, if not weekly then at least once a month.

3) Re the citrus, since I'm not using FP... (quietly bows her head and cringes), I'll ask again whether somehow working a small amount of dolomitic lime around the top of the mix, or scratching it around the outside rim of the pot, would do anything at all to help the magnesium levels? Or are you saying that it won't work because it's not incorporated. I can live with either answer... I just wanted to ask again since you initially responded that "if I was using FP."

4) Thanks for answering. That's actually interesting, because I thought they needed a little higher pH to get those micros. The tsp per gallon of peat (and wood) is a great place to start. I've never actually had any problem with the soil for my tomatoes in this mix, but after a few years of growing in it, I'm just assuming it needs a little boost of something at this point.

-Cheers,
Kristi