Rock Dust, non scientific trial and results.

I had heard a bit about Rock Dust, through magazines and on TV programmes such as Beechgrove Garden. I remember doing some research online about it too at the time, and thought to myself, "Another trend/fad".

But two years ago, one of my allotment plot neighbours was given a bag, by a friend clearing out a shed and brought it down to the allotments. We discussed it for a while and I told him about what I had learned from the research I had done and we decided to run a test. The only thing I had left to plant at that stage was leeks so I dug in half a bag of this Rock Dust to half of the area, planted the leeks and waited.

Unfortunately, my Anne became very ill at that point so tending the plot dropped to last on my things to do, the leeks withered and died from lack of watering. The test then slipped from my mind as nothing visual remained. No results.

So the next year (Last year) I planted the whole bed with potatoes, thinking nothing about the previous years trial. The rock dust treated area was now slap bang in the middle of where my second earlies where planted, but to the right of the rows. The photo below shows last years plants and the yellow bounding box depicts the rock dusted area. NOTE: No discernible difference can be seen in the plants.



I harvested as normal, starting from the top of the bed with the first earlies, when they where gone I continued down the bed onto the second earlies, row by row and the harvest had the tuber size and yield that I had come to expect from the variety (Kestrel) as I grow it every year. About 3 rows in and working left to right, suddenly tuber size and yield increased about halfway accross that row, they where around about 50% larger and yield rose also to around 30% more. The next row again working from the left tuber size and yield returned to normal until halway across, where again it rose once more. At this stage I had still forgotten about the previous years test and continued harvesting and digging. It was only when I had started and finished a row of kestrel and all where at their normal size and yield, and this row was out of the treated area, that the penny dropped and I realised what had been going on.

I was quite surprised as initially I had thought it to be a "Trend/Fad", good but not as good as that had been stated in the media. But I was convinced enough to try again this year, over a whole crop.

The potato bed moved over one as per normal rotation and this spring it had Rock Dust applied and dug in. The chitted potatoes where planted the first week in April and left to grow. One key thing here is that NO manure or BFB or fertiliser of any type was applied before, during or after planting, in fact the plants where barely even watered! Last years crop in this bed where hungry Butternut squash, so not much if any feed would have been around for the potatoes.

I always check progress of my growing spuds and start harvesting when they are big enough to eat (First earlies) this is normally 12 weeks after sowing, at the start of July, however our FE's where ready and being harvested mid June, two weeks early, thats ten weeks after planting. All my FE (Int Kidney) and SE (Kestrel) have now been harvested, and yesterday I harvested the first of our maincrop (King Edward), the latter being harvested at 14 weeks, normally a 16 to 18 week crop, but they have flowered and where starting to die back.

Overall general yield and tuber size is between 30% to 50% greater than I would have expected normally, this is very impressive considering that the plants had no feed whatsoever! The reason they had no feed is because at the start of April, I was very very busy and I simply forgot to add the handfuls of Blood fish and bone to the trench as I normally would do, rain was imminent and forecast for the next few days and the ground was perfect for planting...so I rushed, got them all planted in one day and forgot about the feed. Doh! The plants looked healthy enough during growth so did not trigger me to think..."they need a feed".

One of my plot neighbours also tried Rock dust this season and has also told me his yield and tuber size has increased too. And another plot holder on our site has also grown Kestrel as I did, she has remarked that her crop is nothing compared to mine.

So there we have it, a couple of years testing and using rock dust. Very impressive, certainly not conclusive, definately not scientific, but I am delighted with the results. And I will be using it again next year.

Steve...

PS. I've tried to be as thorough as I can with the above and deliver as much info as possible, if anything is unclear, please do not hesitate to ask either in public or by pm.

 

I bought a bag this year (first time) and have just been putting a small handful around each plant. The instructions say to dig bags and bags of it in initially - I can see the logic in that, but it works out pretty expensive! but maybe my method is false economy?

I'm thinking that supplying a top-dressing will provide minerals, which will correct any deficiency ... but maybe the soil needs a jolly good correction first?

This is perhaps relevant:

"How much to use
A grower of crops or a gardener needs a good response the first year after a fall application. The response in any one year depends on the amount of minerals available to the microorganisms, soil moisture and the amount of inert organic matter.

If the last two factors are satisfactory, as little as 3 tons of gravel dust per acre worked into the top 4 inches of soil should give good results. However, I prefer about 10 tons per acre worked in about 8 inches, since one application will eliminate the cost of a number of more frequent applications and give high yields."

3 tons/acre = 1.25 lb/sq. yd. or 0.68 kg / m^2
10 tons/acre = 4 lb/sq. yd. or 2.2 kg / m^2
20 tons/acre = 8 lb/sq. yd. or 4.3 kg / m^2

I paid 50p/kg for my bag (Seer brand, its 60p/kg for Verve in B&Q), so at 10 tons/acre that would be £1.90 per sq.yd.

No doubt there are cheaper sources than a single 20kg bag

A pallet of 50 x 20kg bags is 28p/kg
http://www.thegrowyourownshow.co.uk/50x20kg-pallet-seer-rockdust-delivered-by-remin-scotland.html
A 1/2 tonne bag (on a pallet) is 27p/kg and a 1 tonne bag is 19p

Perhaps I need to take them up on their offer of a 29 tonne bulk load?

Seer's website says "OPTIMUM ANNUAL DOSE - Apply 2kg per square metre in first year for an initial boost then apply 0.5kg per square metre in subsequent years.
MAXIMUM DOSE: As used at the SEER Centre - Apply 5kg per square metre. Achieves an initial boost and the longer-lasting beneficial effect for up to 5 years or more, depending on soil conditions and type of crops grown. Apply again when soil fertility decreases."
http://www.binnsoilnutrients.com/how-to-use/

 

I just used a 10kg bag of verve Rockdust on my 39ft x 16.5ft bed.

I've just come up from the plot 10 mins ago, I went down to check on my pumpkins. But one of my other plot neighbours was digging up some Kestrel whilst I was there. I can honestly say that mine where twice the size of his, shame I did not have a camera with me. I will get a shot or two through the week now I know he is digging them. Photo's show more than words ever can.

Steve...

 

Good report Steve

Do we know which rocks the dust comes from, there's a lot of them

 

Them's the special Smoke&Mirrors Snake-Oil rocks Zigs

I think the premise is that nutrients of all sorts have been locked up in rock for millions of years. When the rock is mined the "sawdust" that is left is in a suitable format for the minerals to leach out easily. That's what you are paying for - the dust swept up off the quarry floor

http://www.binnsoilnutrients.com/wp-content/uploads/2014/06/SEER-Rockdust-4-facts-banner2.pdf

 

I'd want to know a bit more about the quarry it came from, if its from granite then it i'll be radioactive

 

Ask steve to check to see if his spuds glow in the dark.

 

He'd slap me

 

He'd need long arms

 

Ave you not met our Steve? ees got very long arms

 

Steve...