You do not need to test all 20 beds seperately, you could sample the soil in each of the beds, mix them together, and have one test done that will give your an overall picture. If you are going to grow pretty much the same thing in each bed, ie. vegetables, flowers, the requirements will be about the same and so one soil test is all that is needed, same thing as testing a large garden plot of 400 square feet. What material do you have available to add to your compost? Any leaves? Any possibility of getting lots of leaves? What is the level of organic matter in the soil now? How is the drainage of that soil? How workable is the soil? What does the soil smell like? How many earthworms are in each shovel full of soil from those beds?

Manure is one soil amendment but it should not be used alone. Manure should be used with other vegetative types of organic matter so it will work better in the soil. Most likely you soil in Massachussets will be clay and you will need more than manure to make it workable. Start you project by contacting your local office of the UMASS Cooeprative Extension Service about a soil test for base nutrient and soil pH levels and then dig in to that soil with these simple tests to see what you have there: 1) Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top. 2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up. 3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart. 4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer you soil will smell. 5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy These will help you know what you need to do to make that soil into something good and healthy that will grow strong and healthy plants.

some great ideas! it's good to others realizing xeriscaping doesn't mean catcus and gravel - only. i had rotten luck when i first moved to az, even following what you were "supposed to plant" rules. too much water and then not enough water, all the stuff - it wasn't that at all. my yard is humid due to a tree canopy and living w/i a mile of a river + monsoons (then). i switched to heatloving plants that tolerated humidity and did fine, immediatley. i didn't even have to add water. bananas and cannas do better for me than cactus. i got the idea from an old 1950's s.w. garden club book. a mile away in any direction and i wouldn't be able to grow the same things. there is a lot of variation within any area. don't assume too quick what the problem is. i dig a hole apx 6" deep, fill it and wait for it to drain to help me deciede how long i need to water. if your soil is fast draining, it should show up doing that. you try using some shade cover to reduce evaporation rates, larger leaf plants that use moisture through leaves (and trap it with shade canopy). i've also heard of layering plastic under the roots to help retain water (never tried it). the additives that retain water work very well - esp the kind that look like they turn to a jelly when wet - but it sounds like you've tried those. that's what makes me suspicious that something else might be going on if you've seen no results using things like that. if previous owners used some of the "kill everything" weed killers, it can take awhile before that's worked out of the soil (if it ever is).

I also don't know much about succulents except for a bit of reading and some indoor ones. But I'd also echo the suggestion to check with those who know more succulents and be cautious about adding sand until you know it's okay. From when I have looked at suggestions about succulents, the comments about drainage and watering have been mostly about making sure the roots are not completely waterlogged (and without oxygen) for extended periods, i.e. drains well. And related to that, comments about what to add to the soil related to 'chunkier' stuff like gravel, even wood chips (but I was surprised about taht, no experience). I agree with kimmq above that organic material may not cause a problem with water. Yes, it will tend to absorb some water and release it over time, but I like to think of this as a 'buffering' effect - it will still help with drainage somewhat, but crucially, if it absorbs and releases, it's reducing chances that the below-ground area will be waterlogged (or cut off from oxygen). Put more simply, it may keep the soil moist but not soaked, which I understand is the more serious concern. But ask the specialists )