Opinions, please, on soil improvement

My house was built two years ago on land that was essentially a vacant lot for 15 years. The soil is really poor quality - hard-packed clay with little pebbles mixed in that I can barely break up with a shovel. I haven't been successful at getting a lawn to take consistent root, so I've decided to have most of the front lawn area replaced with a series of interconnecting planting beds around the fence line to minimize the grassy area. The landscaper is going to rototill the soil down about 18 inches and add some stuff to improve the quality and make it easier to work. He says there are two basic options: Replace the soil with a high-quality topsoil, or till in amendments to the existing soil. I prefer leaf compost for the organic benefits, but he recommends gypsum instead because he says the gypsum will start to break down the clay pretty much immediately and add some acid to the soil. It's a big area - the lawn is probably 30x50 - and he's going to cut in perimeter beds around the border about 8 feet wide, so cost is a factor in my decision. What do you all think of either of these options? Any other ideas would be appreciated as well.
Rhonda Richmond, VA USDA Zone 7
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i'd mix in both the composted leaves and the gypsum. your landscaper is correct that the gypsum will help with breaking down the clay soil, but adding composted material will also improve the porosity & water retentive qualities right away. are you sure you want 8 foot wide beds? are there going to be paths to get into the beds without compressing the soil around your plantings? i just don't like beds wider than i can reach into easily for weeding & pruning... and that's about 4 feet wide. lee
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enigma wrote:

I agree, add both.
You want to work as much as possible with the native soil because some plants will try to send their roots down below any portion that has been tilled. If you import topsoil, there will be an interface between it and the soil below. Often, roots will not grow past such an interface, leaving you with shallow-rooted plants that are easily stressed in hot dry weather. If you improve the native soil, however, there will be more of a transition and less of a sharp interface.
This is one reason why planting bare-root roses and fruit trees gives better results than planting them from containers. You might also get better results seeding a lawn instead of sodding. The roots are in direct contact with native soil (albeit improved) and not trapped in a soil very unlike the native soil.
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depending on what good source of cheap, or free if you can, organic matter you are able to lay your hands on get that dug into the soil. If leaf compost is fairly pricey backyard compost, municipal compost (except stuff from sewerage as it can contain heavy metals), mushroom compost, well rotted animal crap etc etc along with the gypsum. Soils and life that lives in the soil arew not too concerned about what type of organic matter it is provided it is well rotted and is indeed organic.
rob
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Good idea.
but he recommends gypsum instead because he says the

Gypsum will help break down the clay but do it as well not instead, gypsum alone will not provide the benefits of compost which are several. Gypsum will not change the pH appreciably and given that many clay soils are already acid making it more acid may be a mistake. Get the pH checked before doing anything. You may in fact want to add lime to make it less acid depending on the current pH and what you want to plant. The time to do it is before the tilling when you add the gypsum and compost. That way all the ammendments get turned under in one go.
It's a big area - the lawn is probably 30x50 - and
30x50 what? I assume feet, not really such a big area to improve unles you are starting with really bad stuff

I trust that these 8 foot beds are low maintenance (eg shrubs with heavy mulch), if not you will have to be walking all over them often and this will compact the soil again.
What do you all think of either of these

I can't say without knowing how bad what you have is, how good the imported soil might be and the difference in cost.
David
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I found this on line resource very good for a general understanding of soil structure and quality. A good bit of bed time reading but worth it is my opinion http://www.ibiblio.org/rge/faq-html/sectionb.htm
rob
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