The many benefits of rock dust

Last year, late summer/early fall, I ordered the 50# bag of glacial rock dust from Plantet Natural

http://www.planetnatural.com/site/glacial-rock-dust.html

and worked this into my beds. All 50# have been used up as well as 12# of crab shell from Neptunes Harvest -

http://www.neptunesharvest.com/cs-612.html

How long does this stuff last? I'm prepping my beds now for spring tomato planting, is there still sufficient nutrients left from last fall or do I need another 50#'s of rock dust and 12# of crab shells?

At that time the beds were also amended with 1-yard of 'sandy loam compost' from the local landscaping supply company and some of my own compost. I may get another load of the sandy loam mix but I sure wish I had a dump truck. I've a bum shoulder and getting that stuff out of the back of my truck is several hours of serious shoveling.

Anywho - will it be over-kill to add more now? How often do you folks add these types of amendments? The rock dust especailly.

Thanks for any feedback.

How many square feet did you cover with your 50#? I don't think too much does any harm.
Here's the suggested application rates for your glacial dust:
DIRECTIONS FOR USE:
Spread 50-150 lbs. Glacial Rock Dust per 1,000 square feet and work into the soil prior to planting. During the growing season, boost plant health by side-dressing in crop rows or around the drip line of trees and shrubs. It's best to work side-dressings into the top 1-inch of the soil.

Here's what my (2 different) old notes for greensand say:

Application Rates
Application rates vary depending on soil conditions and intended use. As a soil conditioner, applications of 25#/1000 ft2 (or 1000#/acre) are recommended. To correct potash deficient soils, anywhere from 20# to 100#/1000 ft2 (or 800# to 4000#/acre) would be applied, depending on the extent of the deficiency.


Light Application 5 to 10 lbs. (or up to 1 cup for every 5 sq. ft.) per 100 square feet.
Medium Application 15 to 30 lbs. (or up to 1 cup for every 2 sq. ft.) per 100 square feet.
Heavy Application 40 to 80 lbs. (or up to 1 1/4 cups for every 1 sq. ft.) per 100 square feet.
Per plant use 1/3 cup.

Mary, you can download the Product Face Sheet on your brand of rock dust here
http://www.gaiagreen.com/products/product_detail.asp?ID=4

Thanks Darius....that spec sheet said "...up to once per year or as desired." so I guess I can [or cannot] add more now. Shipping is the killer as that is $10 more than the product itself. If I can find some locally I'll get it but wait if I need to order from an on-line supplier.

Hard to say what square footage I covered, I have multiple gardens scattered all around. I used one raised bed as my 'mixing bowl', dumping in wheelbarrow loads of the sandy loam mix, adding a bunch of the rock dust and crab shells, mix it up and then wheelbarrow it out to other beds. DH, watching this practice, commented....."Hey, didn't you just dump that dirt INTO that bed? And now you are taking it out???"

Mary,

I will have you know that, because of the link you posted, to "Planet Natural"--I just spent $50+.

Mostly--I was happy to find a source for the 3"x5" yellow sticky pads for use in the house to trap gnats.
Got 25 of them for $8.95 and 10 wire card holders for $3.50.
I also ordered some coir bricks (4) and some liquid See weed/Kelp fertilizer for houseplants. Came in a qt. size.
Concentrate---1/2 tsp to the gallon for "light" fertilizing. One tsp for a more heavy feeding.

I must say--their shipping charges are pretty high! Oh well.......I am NOT used to ordering things on-line....
Gita

I have one garden that has been gardened for nearly 80 years and was farmed before that. Another has continuously been gardened for 39 years and the third for about 10 years.

I think it is reasonable to assume that some of the micro minerals could be a bit used up or leached unless one has done a super job all those years...and that starting from super deep rich soils. Leaching removes minerals in most areas. Arid areas may not need additional rock powders.

Anyway I added a small/moderate amount of Azomite a year ago. Crops are great...course they were great before too!

gitagal.....I know the feeling.....that's how I get LOTS of stuff. Folks here post and I just can't resist.

>> I used one raised bed as my 'mixing bowl', dumping in wheelbarrow loads of the sandy loam mix, adding a bunch of the rock dust and crab shells, mix it up and then wheelbarrow it out to other beds.

I think that's a good idea, if the mixing-bowl-bed has rich organic soil with lots of things growing in it (meaning lots of soil life, not plants!) I do the same thing so that the living population mixture from my helthiest is continually being re-innoculated into my younger, less improved soils.

On the other hand, you could save some wheelbarrowing by giving every bed direct shots of compost or manuare or mulch whenever avialable.

The next is just my opinion, take it with a grain of salt if no one else confirms it. The length of time rock dust remains effective depoends on how fine the 'dust' is. If it were EXTREMELY fine flour, it might be decomposed completley in only a few years. But if it were very slightly coarser, say "dust" instead of "flour", I personally would expect it to last for years or many years.

remember, you are wiating for a grain of ROCK to dissolve completely. I suppose it happens faster in acid soil or with acid rain, and in a very active, organic soil, and in well-aerated warm soil.

But I always thought that rock dust additions were scheduled 5-10 years apart. I could be wrong. Probably the cheaper forms of rock "dust" are not ground as finely as more expensive kinds.

That's an interesting analogy Rick....waiting for a grain of rock to dissolve. The Glacial Rock Dust from Planet Natural was flour-fine. There's a feed store a hundred miles north that sells Azomite and I may get some of that and see if it's different. Thanks for the input.

MaryMcP, I am posting a link to Azomite. You can check the analysis sheet on the site. It likely compares with some other dust.

http://www.azomite.com/

Thanks Indy. I saw that site and have researched and found a dealer in Arizona. Although they are not in Phoenix, someone there will be traveling to Phx next Saturday and is willing to transport a 40# bag for me. We'll meet in a shopping center parking lot off the freeway, just like a clandestine 'deal'. Hahahah. Once I turn this in, I should be good for a good long while.

i didnt see discussion on "lava sand" or did i miss it???
has anyone tried it?? the promoters/sellers say it has a high cation exchange capacity..
guess its suppose to help hold fertilizer in soil..not get washed away..and has is suppose to be
"paramagnetic" ?? now i like to think im a pretty opened minded guy..but reading on this.. sounds
a bit unscientific..??
anyone?? thoughts?
i like greensand.. my roses and tomatoes love it.. of course in correct amounts.. to much of anything
isnt good.. except ice cream,coffee,and pizza.. LOL

You can get Azomite from the seller:

http://www.wheatgrasskits.com if you wish to purchase it online. I have bought from her 2 years in a row. She was on ebay, and I think she is on Amazon as well.

This message was edited Jan 30, 2012 7:15 PM

I'm not sure why it posted twice...sorry!

This message was edited Jan 28, 2012 8:39 PM

Some soil minerals get leached into the subsoil or away in drainage in areas of good rainfall and these areas tend to be low in some minerals. In desert areas the minerals don't disappear very fast oftentimes. Still minerals will not be there if they were never there in then first place unless they have been added somehow.

with lava sand.. ive checked prices around..and im thinking..i should just get some lava
rock at big box store..crush it and use as lava sand..???
anyone else try this???
im so anxious to get gardening..and its turned chilly here.. again.. sigh.. LOL
lettuce is going good though.. probably in a month start another batch..
much thanks...

1/4 inch of 110 year old brick mortar dust just got deposited on our gardens beds, compliments of tuckpointers working next door. Is it "rock dust" I should be happy about ?? !

It predates Portland cement. According to discussions on the oldhouse journal site, it's likely to be "slaked lime and sand".

In another thread in this forum, Ozark said, "I did some reading, and found that it's not good to add fertilizer and lime to a garden at the same time - there's a reaction between them that's not good for soil chemistry."

everything is shooting up in this non-winter, and I was going to fertilize at least the spring bulbs soon. Now I'm wondering whether that's a bad idea with the thick mortar dust.

I guess the question is whether limestone that old is chemically active or not?

This message was edited Feb 27, 2012 3:29 PM

This message was edited Feb 27, 2012 3:48 PM

I believe fertilizing your bulb beds with some organic, slow-release fertilizer is what is usually
done. I did all my bulb plantings a couple of weeks ago.

Same goes for the Holly Tone for all your acid-loving plants. Twice a year. Late fall and early spring.

I like to use all the Espoma "Tones".....They are good for the garden--are not chemical and are slow-release.
Plant Tone
Bulb Tone
Holly Tone
Rose Tone

Of course--everything is early this year. But--you can still do it.

For your first feeding of your roses--add a good handfull of Epsom Salts (Magnesium Sulphate)
around the Roses as well. This promotes new canes to grow up from the base.

Gita

gitagal,
thanks for the good advice. That's about what I normally do as well.
I almost started fertilizing awhile back too, but decided to wait till now -- and then boom, this happened.

I'm hoping somebody can tell me what the impact this thick layer of old brick mortar is going to be

-- and whether I should alter my usual fertilizing as a result?

Looks like the garden moved to mars at the moment!!

If it were me, I would go ahead and do any fertilizing. The mortar likely will take 3 oe 4 tears to break down.

thanks Indy. Missed your reply till now, but have been pretty much doing as you advised -- a bit behind the season, which jumped straight to summer!