Using gravel as mulch

Sepp Holzer talks about using big rocks to trap moisture and to store reradiate heat. Here's an extension of that: In Irrigation secrets of the ancients  - http://www.off-grid.net/2005/05/30/irrigation-secrets-of-the-ancients/.

The idea: "mulch with gravel, sand, or rock. Rock mulch conserves water by shading the soil and slowing evaporation. Gravel-sized mulch is most effective during a hard rain because it allows water to be pulled down into the soil and reduces runoff. Unlike organic mulching materials that absorb a lot of rain water, gravel mulch lets all the water flow through to the soil below"

Benefits: saves half your water, dew trap, heat store.

Really interesting idea. Has anyone tried this?

  Yes! Lots of different ways. Ive tried it with various sized rocks to. Each serve different purposes.

  I actually like rocks about baseball sized for most things, they are easier to get the depth you need, and to move out of the way, and put back. With gravel it just mixes in, and in annual beds, you feasibly could loose their full benefit, or need more pebbles.

   Put down one rock the size of a softball. Look under it after it rains. the water lasts there longer..

   Something Ive learned is an accumulated effect. water will wick out from under a single rock, but it does still help a bit... So have a few sq. feet of rocks now. You get an accumulative affect, I assume it is blocking some of the wicking of the soil from the drier soil nearby. the effect gains momentum as you increase the size.....

    there are tons of ways to use them, and their affect is much more profound then mulch alone especially in dry area, and sunny hot ones. the suns light actually causes more evaporation then the heat. So even protecting your mulch layer from the sun compounds its benefits. wind is the next in line after direct sunlight, and of course theres no wind under a rock.... the atmosphere itself wicking water out of the soil is the third most prevalent, and under the rock more so then mulch this isnt an issue either..... heat is the fourth factor (this values are based on a conglomeration of sources, and through tests seem valid to me, but it works for each of these factors either way) and well its colder under a rock.....

       so rock mulches are indispensable for my dryland systems..... Im working on testing the optimum results of various sized rocks for different applications, both places where you wont be moving them, and places with annuals were you do. Moving rocks around might not fit others ideas about what forest gardening is, but where I live its prudent imo....

this post has me thinking about a thread i created that no one responded to. about how i could deal with a slow moving seasonal stream. i wonder if throwing a lot of my extra rocks in it would do away with the standing water algae while also preserving the water in the hot months particuarly if i take out a few of the trees shading it.

the only drawback i can think of using rock as mulch is if you ever intend to mow or till anywhere near it. not really a problem for me.

boddah wrote:
this post has me thinking about a thread i created that no one responded to. about how i could deal with a slow moving seasonal stream. i wonder if throwing a lot of my extra rocks in it would do away with the standing water algae while also preserving the water in the hot months particuarly if i take out a few of the trees shading it.

the only drawback i can think of using rock as mulch is if you ever intend to mow or till anywhere near it. not really a problem for me.

I would think the silt in the stream would fill in the holes over time? then just roll over it, and make a new path.....

You can use barley straw for algae control, people use it in waterfalls in their back yard ponds and such....

What type of algae? a floating type? or greenwater type? If its a floating one, I would think its a resource as you could harvest compost every few days.

Using the baseball size rocks make a lot of sense Silverseeds. I was curious how they would put their compost down with the gravel there. It's hard enough to move gravel with a shovel.

How far out from the trunk and how densely do you put the rocks? Do you compost under the rocks as well?

thanks

around our house in the ornamental decorative beds we have almost replaced mulch with a type of creek pebble.  i was amazed at how well it "mulched" the beds.  really holds the moisture.  it does settle though  and i can see where eventually some may need to be retopped to keep the level up to where we want it.  but in the long run its cheaper than the traditional hardwood mulch..  and the plants/bushes/trees seem to be doing rather well.  better than i thought they would in comparison to real mulch.

we've found that the barley straw did nothing for our pond.  ive read the claiims and have used it for a number of yrs. but it seemed to be a waste of money.

I think it really depends on your climate and intent.
In my wet-ish, temperate environment, stones as mulch are nearly always a total pain: lots of people 'put in' river pebbles over weed matting and think they'll never have to do anything ever again, and I get to weed and move them. Not a fan!
I'm just thinking of the small, 'pebble' type stones.
I've no idea how one is supposed to feed the soil underneath small pebbles, but in the situations I see, people are generally using stone mulch in an attempt to stop plants growing, rather than encouraging them. But mostly I'd say that how to feed the soil is just not a question that entered the equation.
SILVERSEEDS, are you using stones in areas where you're fertilising?

Leila wrote:

SILVERSEEDS, are you using stones in areas where you're fertilising?

in my experiments, in my conditions, with materials I have on had.... my experiments show me a good layer of compost, with a standard type mulch, with rocks over it is the best. this is on top of the soil on many perennial plants that grow in my native soil, and over top my prepared beds as well.

I have found each serves divergent and related purposes. the compost is where I have my life forms, the mulch protects them and all the other things mulch does, and the rocks over that do their thing....

I intend to pull back the rocks and add more mulches every few years, ensuring I have something for those soil beasties to dig into.

On my annual beds i dont always use them at this point, but I will especially as I bred the crops that will ultimately be what Im growing.

SILVERSEEDS wrote:
in my experiments, in my conditions, with materials I have on had.... my experiments show me a good layer of compost, with a standard type mulch, with rocks over it is the best. this is on top of the soil on many perennial plants that grow in my native soil, and over top my prepared beds as well.

I have found each serves divergent and related purposes. the compost is where I have my life forms, the mulch protects them and all the other things mulch does, and the rocks over that do their thing....

I intend to pull back the rocks and add more mulches every few years, ensuring I have something for those soil beasties to dig into.

On my annual beds i dont always use them at this point, but I will especially as I bred the crops that will ultimately be what Im growing.

very good points and we've found similar results.  around shrubs, bushes, hostas and such.  the gravel has been installed over existing mulch.  and it has been for a couple of yrs now.  and they seem to be flourishing.  so far ive seen no need to pull the gravel back to refertilize. but if and when we do it wont be to big a deal to scrape the gravel back around the shrubs, shovel in some compost and reinstall the gravel.  lot less work and money involved than our previous efforts.

toddh wrote:
Using the baseball size rocks make a lot of sense Silverseeds. I was curious how they would put their compost down with the gravel there. It's hard enough to move gravel with a shovel.

thanks

this has been my job for a long time. most my life really (shoveling) and you have a good point. but using a square shovel and on a hard flat surface you can scrape it across and pick it up no problem. when having to enter it from a pile a round shovel with a handle and a place for kicking is needed. dont whack it but put the shovel on the surface kick and drive it in.


as for me ive been using some rocks intuitively like this and also id seen it in a holzer video. i have not gone much out of my way but when i dig a hole for a plant i take the rocks out and put them on top.

interesting thread

I like the baseball-sized rock thing.  Mostly because I find myself digging out all kinds of construction waste when I want to dig a new plot, which includes all manner of small and large piece of concrete at every level in the ground.  It would wear me out to have to move gravel all the time.  Is this rock bought at stores or gathered around the property?

    Ive got two places. I dont have to many rocks around my place in town. Ive got a place in the mountains though that has then everywhere, that where i get mine....

    I realized I didnt explain myself to well before. in the perennial beds I use rock of any size really as long as the top side wouldnt be collecting water rather then letting it pass. Some eggs size or so, some football size or bigger. All of them things I could move every few years if i wanted to remulch the perennial beds. which is wise, its good for the biota. Every year might even be better, but mine seemed to not "need" it for about 3 years. Probably depends a lot on where you are and the quality of materials youve got to.

    the baseball sized ones are for areas where I move them alot. I like those to be roughly the same size, and thats a easy size to work with. I can sweep my hand across a decent sized area, ensure I move them all fast and simply, do whatever work I was intending, and scoop them back.

every year i toss pea gravel into the forest garden. the best benefit i find is that is protects very young seedlings from various things like weather or predators.

SILVERSEEDS wrote:

    Ive got two places. I dont have to many rocks around my place in town. Ive got a place in the mountains though that has then everywhere, that where i get mine....

    I realized I didnt explain myself to well before. in the perennial beds I use rock of any size really as long as the top side wouldnt be collecting water rather then letting it pass. Some eggs size or so, some football size or bigger. All of them things I could move every few years if i wanted to remulch the perennial beds. which is wise, its good for the biota. Every year might even be better, but mine seemed to not "need" it for about 3 years. Probably depends a lot on where you are and the quality of materials youve got to.

     the baseball sized ones are for areas where I move them alot. I like those to be roughly the same size, and thats a easy size to work with. I can sweep my hand across a decent sized area, ensure I move them all fast and simply, do whatever work I was intending, and scoop them back.

Ithink I get it.  Gonna have to search for pictures.  This sounds perfect for vacations, as that is my biggest concern with the garden, being away from it during a hot, dry spell.  I wonder if the "river rock" I see sold would work.  Yeah, something new to work on!