You can buy soil test kits but I don't know how reliable they really are.
Go on rainbird.com or orbit.com. One of them or maybe both you can get assistance and guidance on laying out sprinklers. It requires hours and hours of planning and all depends on soil, weather, plants etc. I think you can even pay them for a design.
I dig up rocks all the time of various sizes up to 8 inches and you want some if you have clay. They can help in drainage.

1. No need to test the soil. You have "Poway Conglomerate", pretty much defined as how the USDA describes it except that it's not really "clay" -- it's heavy silt and or sand, "cemented" together with calcium carbonate (lime) or iron oxide. The cementing makes it as hard as concrete (or "clay"). The calcium carbonate situation makes for nutritional deficiencies, not because there are no nutrients in your soil but because they are ionically bound up. Choose the right plants for your kind of soil and you don't have to work on "amending" it. There are thousands of plants that will grow happily in "Poway Conglomerate".

2. Do NOT use amendments unless you're planning on growing annual vegetables, annual flowers or "woodland" plants (camellias, azaleas, ferns, hydrangeas and such). If you're planning on putting in basic landscape plants or fruits trees, simply dig a wide hole, break up the conglomerate, remove the pebbles and stones, plant the plant and mulch well with a nice composted organic material. Also includes roses.

2a. For plants that are not adapted to your kind of soil (those that show signs of nutrient deficiencies [chlorosis]), use an appropriate fertilizer. (I like citrus food fo just about anything that shows yellowing).

3. Never use "topsoil". It causes "interfacial tension" in soils. Work with your native soil and mulch well.

4. Don't throw away the stump grindings and trimmings, don't till them into the soil. But do use them as a mulch.

5. The bulk of the price of putting in a sprinkler system is the trenching for and laying of the main line. Per square foot, the fittings/heads won't cost you any more except in materials and that price is there whether you use a professional or not. On the other hand, some companies will do "time and material" and are open to working with the client (if you're at least halfway competent/flexible). That'll save you on labor time. Check the yellow pages for licensed contractors and throw the options at them.

Joe (a San Diego baby who dug a LOT of rocks out of gardens down there)

GG1950, can you explain a bit more about interfacial tension caused by topsoil? I've only ever heard that term used in regards to liquids, such as the surface tension of water. Are you saying that topsoil worked into the soil somehow causes water repulsion and leaves the area drier?

dicot:

To put it simply, topsoil placed ON TOP of existing native soil creates an area -- where the two soil textures join -- that is no longer conducive to water penetration. The pore space difference makes it difficult for the water to continue moving downward. It's that "bathtub effect" that was described by the landscape and nursery industry decades ago.

"Working" the topsoil INTO the soil is a different matter. This is essentially "amending" and that's not good, either.

Joe

Joe,

Very interesting info! Thanks.

Why is it a bad idea to amend the soil in general? Do you mean from an environmental perspective? (That it's better to try to work with what you have?)

Would you think that adding compost is a bad idea too?

I'd like to prepare a part of our yard for some lawn, and another big patch for a vegetable garden -- for those areas, do you recommend "amending?" My plan for those areas would be to add compost (free from Miramar Landfill) while tilling the dirt. And I would use mulch (my stump grindings) to cover the surface around plants.

Thanks!

In such soil, the OM will break down into very small, extremely stable, particles that will clog pore spaces which will impede drainage. The same thing happens in sodic soils.

Ryan

Amending the soil is old time wisdom. Still universally accepted in the industry but that's despite extensive research at several universities throughout the country.

Essentially, plants adjust most quickly and better to native soils. Whatever the soil is -- sandy, gravelly, rocky, claylike, etc. The basic assumption is that you've planted plants that are adapted to your soil. The good news is, most plants are quite tolerant of a wide range of soil types.

If you decide to plant a plant that simply does not like your soil, no amount of amending is going to fix the situation in the long run.

There are the three exceptions to the new amendment rule, as already noted. Do amend the whole bed for the vegetable garden but don't worry about amending for the lawn. Do prepare new soils by digging deeply, breaking up the soil and removing stones, pebbles, sticks, shoe and dead bodies.

And do mulch newly planted plants (not lawns, of course) and do provide an all-year, "no-till " mulch in your vegetable garden.

Sustainability is about minimal input.

Joe

Thank you Joe! Will do as advised.

Although I know nothing about San Diego soil I do want to reinforce the use of mulch. It took me years of experimenting with my clay soil to appreciate the value of maintaining a constance mulch. Mulch will breakdown at a rate depending on its composition. Stump grindings will be slow, or among the longest lasting of materials. Its soil cooling effect, weed suppression and help in avoiding soil compaction are easy to observe. Al

Although I know nothing about San Diego soil I do want to reinforce the use of mulch. It took me years of experimenting with my clay soil to appreciate the value of maintaining a constance mulch. Mulch will breakdown at a rate depending on its composition. Stump grindings will be slow, or among the longest lasting of materials. Its soil cooling effect, weed suppression and help in avoiding soil compaction are easy to observe. Al

I'm in the Coachella Valley (should be conch shell valley.. little conch shells all through the sand/clay because our water table is high and there is a water line on the mountains and the conch shells come from decades of being under water), and I have made friends with a "gentleman farmer" here in Indio.

He concurs. Do NOT ammend the soil. Stick the plants in. They will do just fine! It's nice to get reinforcement for that!! I was going crazy trying to find Al's mix. It is impossible here in Southern California to find those pine bark fines, and now......... I don't need them!!

Good luck with your yard! It sounds amazing! Look forward to the ongoing process!

My yard is probably similar to what you have found - I'm in NW SD county atop an ancient marine terrace (I've found streambeds), on a 'cut' lot where the airport was once situated. The ground is exceptionally hard when dry, roots will not penetrate, and a bucket-size hole takes a day and a half to drain. I once stuck a plant in a good-sized hole, w/out amendment, and it died as the roots circled the hole and it drowned in the winter.

My observations
- soil testing kits found in stores don't work
- a soil 'jar test' is simple and will give you the proportion of silt, sand, clay and bio-materials
- a rototiller is fine if you want to run the Iditarod down your street, cause the machine has no hope of getting its claws in. A small jackhammer and strong shovel are my tools of choice - once the ground is saturated it will slice pretty well.
- I added massive amounts of mulch, worm casts from my vermi-ranch and compost to improve the drainage and keep the soil from reforming hardpack. It's amazing how much was used, and the difference it made.
- the entire garden, except the raised bed veggies and a few fruit in back, is drought tolerant and hand watered twice a month. Grass invades landscaping unless you are diligent, and I only have grass in the back. ...for now.
- my garden blooms all year, and my water costs $15/month in summer
- Joe's comments are spot on
- French drains redirect rain water into the garden. If you're digging anyway, it is not that much effort or $ to add them.

Here is a link that might be useful: front garden overhaul

Interesting stuff. I live on top of a canyon in Clairemont. Poway conglomerate and terms like cement describe the soil well.

To GG1950/Joe- (or anyone else of course) In terms of amendments, (which I see you say not to use- in most cases) I am interested in your thoughts on adding gypsum and or sulfur in an attempt to lower the soils PH (for my vegetables) and in an attempt to help break up the clay. (or cement?) Could one overdo it on the calcium with the gypsum? You said something above about Poway conglomerate containing calcium carbonate.

Also, any tips on unlocking the nutrients ionically bound up in the soil? I have heard and read there can be an over abundance of some nutrients in the soil here (especially potassium) due to limited rainfall leaching out said nutrients.

Very interested on different San Diegans takes. Thanks.

porewit, et al:

1. I'm a firm believer in "right plant, right place". That is, San Diegans have a certain kind of soil and they shoudl stick to plants (overall) that are adapted to that kind of soil (heavy and neutral/alkline). The good news is, there are thousands of plants that fit that kind of soil. I think California gardeners, in general, make too big a fuss about the pH of our soils here.

2. Gypsum does not break up clay nor soils cemented together by iron oxide or calcium carbonate. Gypsum is used to break up soils that have no structure due to an abundance of salts (we call them "sodic" or "alkali" soils; not to be confused with "alkaline" soils). The gypsum replaces one ion for another (much as with water softeners) and allows such unstructured soils to develop a structure (flocculation). Our soils do NOT need calcium.

3. Sulfur doesn't really change pH significantly and it definitely doesn't work to alter pH over the long run.

4. The "tip": mulch (a verb). Mulching with a semi-decomposed organic material changes, at least subtlely, the chemistry of the soil and does, indeed, allow nutrients such as calcium and iron and other micronutrients to become available to the plants in the soil. Aside from choosing the right plants (see above), this is the best thing you can do for plants that DO need a slightly different soil chemistry.

5. Yep, some of our soils are high in potassium and that can be toxic to some plants. Not a lot of plants, mind you. A few special Australians. But again, it's all about right plant, right place.

Joe

Thank you Joe for the info. Any thoughts on the mulch and compost from "greenery" at the city (Miramar) landfill? It's free if you load it yourself, but sometimes it seems funky. Thanks again and take it easy!

I don't know the quality of the compost from Miramar. But when you describe it as "funky", I'd compare it to most composts that I've seen from city/county landfills.

They are "funky" -- they're never composted enough, they're filled with trash (including non-biodegradable plastics), they include weed seeds and other seeds that sprout, and they often include material that has been sprayed with herbicides.

If the price is beyond refusal (slight pun intended), get yourself a load and start a new compost pile with it. Treat it as any good compost pile: keep it moiost and turn it often. And in the process of turning it, do your darndest to remove the non-biodegradable trash. Then use it to mulch periphery areas. Keep it out of the vegetable garden and orchard.

Joe

That pretty much confirms what I've begun to wonder. Thanks again,I appreciate the insight from someone who's been gardening in the area longer than I have. Any time you feel like posting your SD vegetable bed tips, I know I'd be interested.

Wow, this is a very useful thread for planting in our region. Thank you.