I have a nice flat spot in my property with good drainage. It is currently grasses in. Can I spread a base of 3" of stone dust right over the grass?
Not if you want it to last.
honestly if the grass drains well and is level, just ride on it.
organic material is what creates the mud and poor drainage so spreading stone dust on the grass without separating the layers just means you will work grass into your stone dust and be right back where you were, only poorer.
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Haha thanks. There wouldnât be much organic material in there as it would get very light usage and the horses are kept in a paddock off of it. Do you mean decaying grass creating the organic matter?
Yes, decaying grass is organic matter. When it is alive it is fibrous and provides a lot of shear strength to the footing, and even some bounce. When it is dead it just becomes slick and gooey.
Ride on the grass, and see how it holds up. If it doesnât, you can always go forward with grading and adding material later.
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If itâs just for you, and youâre trying to make it firmer / less slippery, then this is not the worst thing you could possibly do.
Just keep in mind that if you ever want to do it for real, youâre going to have to scrape off the grass and dirt plus what you added and get down to something you can work with as a proper base.
I cheated. We found a naturally crowned area of sandy clay, which I had cleared and leveled. Then we dumped crushed granite on it. This only worked because I essentially had a natural base once the trees and pine needles were scraped away â no topsoil to speak of.
This is what I ended up with: https://www.flickr.com/photos/wsmoak/39407934731/in/dateposted-public/
Yeah, but wsmoak, you didnât drop that on top of 3" of live grass, right? You scraped it off first.
Part of the question is based on our preconceptions of what âgrassâ means here. A live, wet, thick mass of grass is different from say california golden scrub in September. Putting 3" of stonedust on live, thriving grass is like putting it on a wet, lumpy sponge.
We put down gravel around our field to make sort of a track for driving. The hayfield was just too bumpy, even with careful, close mowing. It really made a big difference, and now 10 years later the grass has come up through it so itâs harder to see but it is still flat and better footing for the pony and less bumpy for the people.
Wsmoak that actually looks really nice!
So the âproperâ way to do this is to have the topsoil removed and backfilled with 4" of stone dust and 2" of sand graded for drainage Iâve gathered?
Get the USDF arena construction booklet titled âUnderfootâ. Best $10 I ever spent.
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It depends entirely on the soil.
I rode at a barn that was on very sandy soil and they literally just dumped a couple truck loads of sand and spread it around. It wasnât 100% level (had a slight slope over 200 feet or so) but was quite rideable anyway.
If I tried that on my very dense clay, the sand would be 6" underneath the clay in less than one season.
For my arena, my excavator took 18" of soil and then put in drainage, then built a riding surface on top of that. Much more expensive but if youâre going to spend the money, you want it to last.
If you have reasonably good drainage, your method might work. Your sand and stone dust will probably mix together unless you compact the base. Itâs not the end of the world if they mix, but again - if the ground underneath isnât going to be solid, you will lose the footing into the soil.
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Maybe ask your Farm Service agency Natural Reserves officers about how that works where you are?
Here, you may plow the grass under, water, crown and compact the dirt, similar as a pad for a house, then add the other materials on top.
Many arenas here people just ride on the lightly plowed ground and do fine, but it doesnât dry quickly.
If it rains, they just donât ride there until it dries enough for it, which may take days.
In general, yes. Remove the organics/top soil to the sub-soil. grade to insure proper drainage out of the arena, install compacted base, install footing. In some cases, geo-textile non-woven fabric is installed below the compacted base. If you do it correctly, it will last and last and last. It will also be much easier to maintain.
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We took our time and did it right (Iâm on cherty clay in central AL). Took off the topsoil, leveled it with a slight (super slight) crown and let it sit for over a year to ensure I had it right. Topped that with 4" of stone dust and rented a steamroller to smash it down. Let that sit, too. Finally added a little 1/4 by fines (like the crushed granite above) and rode on that for a few years - when I wanted to it added a little salt for cushion and worked it in.
The USDF booklet recommended above is great- I find that grass can be slippery when itâs super dry/drought conditions and also too squishy when wet. In some areas (like 100 miles south of me) itâs sandy/loamy enough that itâs fine. Thatâs not true here 
