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jillyluis

Post construction dirt preparation

jillyluis
11 years ago

Hi, we are doing a lot of work to the back of the house. The grade currently is six inches below grade, and the soil is very poor quality, and quite compacted. The dirt has to get sorted out within the next week, but I still haven't figured out the garden design yet. The space is small, but there will likely be some perenials, a veg/herb bed and a little grass. I'm just not sure where.

What do I do about the compacted soil? Do I ask the excavators to break it up while they are here next week digging the foundations? Or is just putting a 6 or 9 or 12 inches of good soil on top enough?

How much additional soil should i have them remove so I have nice soil on top?

For the new soil, how much compost v loam? Since I don't know what is going where,I'm having a hard time figuring it out.

Thank you ever so much

Jill

Comments (2)

  • NHBabs z4b-5a NH
    11 years ago

    Whatever you do, I'd recommend that you do it to the whole area regardless of whether it will ultimately be lawn or perennials or herbs or veggies. They will all be happier if the soil isn't compacted and the organic matter and nutrients aren't at subsoil levels.

    I would loosen up the soil, preferably with a spading fork or pry bar plunged in and wiggled. I usually just add composted manure on top of poor soil and then let my planting and the critters like small rodents and worms mix it in, but in an area that we had heavy equipment about 4 years ago, I recently discovered that the underlying soil is still quite compacted. I'm not a believer in having heavy equipment fix soil compaction - seems contradictory to me, and a rototiller only goes a few inches deep which is why I suggest a manual tool plunged in and wiggled.

    What is considered loam varies considerably from one area to another and one supplier to another, so I would suggest asking around near you for suppliers and see how happy other folks have been with their materials. Since I have fairly fine sandy loam with little organic matter, I pretty much just add organic matter to my garden areas, but you will need to decide if the loam available to you will create what you want or if you need to add more organic matter or sand or whatever. Some questions to think about in determining what you should use to improve this area:
    Is there a slope toward or away from this area?
    Is there good drainage with the current soil?
    What is the current soil texture? (sandy, clayey?)

    If there is currently a good mix of clay and sand, you only need to add organic matter. If It's sandy, loam and organic matter would be good additions. In either case, you may want to mix it in some with a spading fork, shovel, or a rototiller. If it is near the top of a slope, adding coarse organic matter on the surface (mulch) may help prevent both soil and moisture from moving too fast downslope, both before planting and after planting.

  • mad_gallica (z5 Eastern NY)
    11 years ago

    The grade currently is six inches below grade

    What does this mean? Who determined what the grade should be, and what is the reasoning behind raising it? If it is for drainage reasons, you'll want a particular soil type since that affects how the drainage works.

    the soil is very poor quality, and quite compacted

    Again, how was this determined? 'Quite compacted' IMHO, means 'former driveway'. Unless it has been driven on routinely, for years, it isn't compacted. It may be hard, which is fixed by organic matter, but it isn't compacted.

    Unless some sort of soil test has been done, it is impossible by looking to determine how good a soil is going to be. Good soil comes in a wide variety of colors and textures.

    The dirt has to get sorted out within the next week

    This is the biggest 'Why?' Is the work being done going to completely block access? If the drainage situation is so bad that is has to be fixed immediately, that is another issue.