Author Topic: Weigh your dolomite if you're still measuring in cups!  (Read 2391 times)

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Weigh your dolomite if you're still measuring in cups!
« on: June 20, 2017, 09:22:33 am »
Disclaimer: This post was originally posted by Full Member, Eric-02476. This user is located in Zone 6A Eastern MA. This was originally posted on May 19, 2014.

I've learned the hard way that blindly adding "2 cups of dolomite" isn't such a great idea. 2 cups can add up to much more than the recommended 1 pound. Read on:

To save major money, I buy 40-pound bags of pulverized dolomitic limestone for about $5 from my local hardware store, in the lawn section (gasp). The label analysis shows calcium and magnesium in the desired concentrations and proportions. All good for Earthboxes, right? Yes, and so much cheaper than buying small bags of dolomite from the horticultural section.

But I forgot one thing: density.

See, as an avid Earthbox user for 10 years or more, I've long been in the habit of following the "classic" instructions to add 2 cups of dolomite when replanting. This year, when reviewing the latest replanting instructions online, I see the company now says to add one pound. So I got out my kitchen scale, sheathed it in a ziploc bag, and weighed 2 cups of my dolomite. It came to almost 2 pounds!

So, I've been WAY over-liming my EBs for who knows how long. Perhaps not coincidentally, I've had more trouble than usual in recent years with inexplicable signs of nutrient deficiencies in various plants. I wonder if I've been making the potting media too alkaline over the years. That can certainly affect nutrient uptake.

Bottom line: know how much YOUR dolomite weighs, especially if you're going rogue like me and buying it in those 40 pound bags in the "wrong" section of the garden center!

Eric

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Re: Weigh your dolomite if you're still measuring in cups!
« Reply #1 on: June 20, 2017, 09:30:12 am »
Disclaimer: This post was originally posted by Hero Member, mjb8743. This user is located in Zone 7, South NJ, Garden State. This was originally posted on May 19, 2014.

It can get pretty confusing when there are different forms of dolomite available. I'm currently using Espoma Garden Lime, which is pelleted. Those pellets are a coating of some sort that encases the lime. So... exactly how much dolomite am I actually getting in a pound, or in 2 cups  Huh?

I also buy the 40 lb bags of pulverized dolomite, and I always have used the 2 cups. Fortunately, I also switch out about 1/4 of the mix with fresh. I think this helps keep the ph from increasing to dangerous levels.

Mickie

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Re: Weigh your dolomite if you're still measuring in cups!
« Reply #2 on: June 20, 2017, 09:32:33 am »
Disclaimer: This post was originally posted by Hero Member, linear249. This user is located in Zone 8b. This was originally posted on May 20, 2014.

Eric - This is some discussion on the amount of dolomite to add.

I was only adding 1 cup which weighed 1#.

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Re: Weigh your dolomite if you're still measuring in cups!
« Reply #3 on: June 20, 2017, 09:33:19 am »
Disclaimer: This post was originally posted by Full Member, Eric-02476. This user is located in Zone 6A Eastern MA. This was originally posted on May 20, 2014.

Thanks for the replies! Mickie, I bet you're right that refreshing 1/4 of the mix helps keep the pH in balance. And thanks for the link to the other thread, Aline. I'm still a bit confused about how much dolomite by weight or volume Earthbox officially recommends, but with my 40-pound bag dolomite, 1 cup is about 1 pound. Perhaps the system is more resilient for pH and I'm worrying too much. I'll see how this season goes with just 1 cup/1 pound. So far the plants are quite happy.

Eric

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Re: Weigh your dolomite if you're still measuring in cups!
« Reply #4 on: June 20, 2017, 09:34:55 am »
Disclaimer: This post was originally posted by Newbie, GregRichey. This was originally posted on June 22, 2014.

One thing I have found that can be a problem is that not all potting mix needs the dolomite. Some potting mixes already have it added. If you look at the ingredients on some potting mixes you will see they may have dolomitic lime added already. I bought a cheap ph tester and checked a bag of mix I had and it was just under 6.5. The label said it had dolomitic lime added I skipped adding more. The plants did great and now I am thinking last year I had at least a few boxes I put the lime in that did not need it. Maybe they changed the potting mix I have been using?

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Re: Weigh your dolomite if you're still measuring in cups!
« Reply #5 on: June 20, 2017, 09:36:28 am »
Disclaimer: This post was originally posted by Hero Member, gardendoc. This user is located in Ocean Springs, MS Zone 9a. This was originally posted on June 22, 2014.

Greg, the dolomite added at the factory is no where close to what is needed. The dolomite does impact pH, but its main job is supplying Ca and Mg.