USDA zone 6B
9" rain, 16" snow
gently sloped generally northern aspect
find sandy loam - thin soil (4' progressing to bare rock)
very little OM
hard westerly prev winds
I'm trying to revitalize my Pinyon/sagebrush land. I have fine sandy loam on top of sandstone which is somewhat porous naturally, and also fractured in places.
I think this because when we get rain (rarely) or melted snow flowing, there are places on my property where the flow will suddenly disappear, and the microclimate changes rapidly downhill from there: fewer plants in general. It seems that the water is dropping through cracks in the rock and is gone. (Well not gone, but not available to me. Perhaps recharging the shallow aquifer?)
I remember the illustration from geoff lawton's Food Forest video that using a swale the water will flow underground, then hit an impermeable layer, which can cause the water to make springs and ponds. My concern is that I'll lose that water.
Note: I do plan on doing swales, mulching, windbreaks, cover crops and planting a food forest anyway, but I had this thought and couldn't shake it. Perhaps it's not a concern at all, and I'm just worrying about nothing. Building the soil will retain more water than I would have anyway.
Question: Should I be concerned about the water disappearing? What should I do about it, if anything?
Well, it's ~35 acres, mainly decomposed sandstone, and it has a fairly gentle, even slope to the north.
If I do the math, it's about 1.1M gallons of water, or about 26 acre-feet. I also am mainly just dealing with the water on my property, there's almost no uphill off-property drainage, perhaps 1/2 to 1 acre.
The trick I think is in keeping it, or in Geoff's words, "anti-evaporation strategies."
I'm not sure if I could create a spring if there's water that's just disappearing into the fractured bedrock, instead of "bouncing" off and emerging downslope somewhere. This sandy loam drains extremely well.
Come to think of it, I'm also going to have to consider alternative pond sealing strategies. We do have a bentonite quarry nearby, and permits are inexpensive, though the work is labor-intensive.
I'm also not sure how much of the property has fractured water-swallowing sandstone, but at least some of it does. I could seal the one area, but my suspicion is that it's broken in multiple places, which would require cost-prohibitive work. Increasing the soil's ability to hold water should help too, right?
I've read/been reading several PC books, and I think I need to do swales on contour, and plant biomass N-fixers, trees, and cover crops liberally. Cover the soil, shade water features, berms and windbreaks. Anything else?
EDIT: Should be zone 6A, not 6B, though I think the USDA is still wrong. We hit -20F last year or two ago.
In an area that gets 9 inches of rain, I would choose a property that is 3/4 exposed rock over a flattish one with deep soil covering the whole thing. With mostly rock, there would be plenty of well watered spots where the bedrock sheds flash flood waters into little valleys. If there were a way for you to rob water from one area to feed another, I would pursue that. Five well watered acres will give you much more than you will get from 35 acres of desert. Even if you can get 1000 sq. ft. here and another over there, your useful crop area will be better than the current situation.
Cam Mitchell wrote:... I think I need to do swales on contour, and plant biomass N-fixers, trees, and cover crops liberally. Cover the soil, shade water features, berms and windbreaks. Anything else?
Bear with me here because this is more me thinking out loud than me imparting any sage advise -
Along with all these things you'd want to do everything you can to increase organic matter in the soil: chop-and-drop, get ramial wood chips if you can (tree services!), compost/compost tea. All those things will get you organic matter and (more importantly, in my opinion) start building up the micro-organisms that live in and process the soil. As these guys go you get boi-slimes and mycelium running all over, which really hold the moisture and the fungi can actually transport the water (and nutrients). So now you've got lot's more water sticking around in your soil, with lots of growie things slowing it down and transporting it, but water's going to do what it does, which is try to flow down when it can - more water in the soil means more water has to move sideways waiting for the water below it to move down, so now you have a better chance that the water is going to hit the surface at a gully/depression before it drains away completely - you have a spring.
You could probably also help your cause over the years by continually adding small amounts of that bentonite clay everywhere. What I mean is don't add so much that you seal the top of the soil and make everything run off but maybe add a pickup load sprinkled/blown all over the place right before the rainy season. If it's just a little bit compared to the rest of the land you should get some decent infiltration into your soil which with aid with cation exchange and water retention in the short term and eventually you should get a clay layer deeper in the soil that will start to become impermeable to the water and get some subsurface sideways water flow going along that layer. Once again, where the water hits the surface at the dips and depressions you should get a spring. Once you've got your springs I'd stop adding the clay.
Once again, thinking out loud here so take it with a grain of salt. Hopefully I'll have more concrete advise after I finish Geoff's PDC!
Dale Hidgins wrote:With such low rainfall, your best hope of collection is probably going to be by trapping snow and having it melt into deep beds of organic material. Strata like yours can send the water very deep and it may emerge miles away or feed distant wells.
Yep, I think you're right about the snow. Not to your point, but I am many miles from any sizeable stream, unfortunately. You expressed exactly my concern with losing all that water.
I'm concentrating on my zone 1, 1-2 acres around the house, which is about a high on the property as you can get. I can't really move the house, so uphill water harvesting is less than it would be, were the house midslope as Geoff suggests. Hmm, where could I rob water from...?
Michael Newby wrote:Along with all these things you'd want to do everything you can to increase organic matter in the soil: chop-and-drop, get ramial wood chips if you can (tree services!), compost/compost tea. All those things will get you organic matter and (more importantly, in my opinion) start building up the micro-organisms that live in and process the soil. As these guys go you get boi-slimes and mycelium running all over, which really hold the moisture and the fungi can actually transport the water (and nutrients).
That's funny, I didn't know what "ramial" wood chips were until I was reading "The Holistic Orchard" just last night!
Yep, tree service companies are great places to get free wood chips. I got 20-30 yards last year, though you never know what kind it will be. Half of it was juniper and other evergreens.
Now I'm out of town and it's not convenient for them to drop chips here.
It's good stuff, your comments mirror my thoughts on holding water in the soil. So maybe I'm NOT crazy. SEE! SEE! I told you I wasn't!
Those techniques are what I've been doing for years in my garden, it's just on a much bigger scale now with the new property.
I badly want a spring or some other surface water. It makes me nervous only having a deep well for water.
AFA the clay, I will try it. Hey, what's the worst that could happen?
So if I understand correctly, I should do lots of deep organic matter and get fungal activity going (juices, etc), and try to lock up or at least slow down water as much as possible. Right?
Jd Gonzalez wrote:Yes, swales on contour to slow and hold water, deep mulching to hold the water closer to the surface while slowing it as it sinks into the soil, and ground cover and plants to shade and slow evaporation. The landrace fungal and microbial strains will go to town in that environment.
A word I had to look up!
Landrace; A local cultivar or animal breed that has been improved by traditional agricultural methods. http://www.oxforddictionaries.com/definition/english/landrace
"...All components of the [plant] population are adapted to local climatic conditions, cultural practices, and disease and pests." http://en.wikipedia.org/wiki/Landrace
Awesome, thanks Jd!
Now to rent the excavator...