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Post by octave1 on Apr 1, 2024 16:09:43 GMT -5
We had a concrete slab (half of a basketball court that came with the house, cracked and no longer in use) removed from our backyard, and under the concrete we found a bed of sand some 8"-10" deep. Underneath the sand there is soil, which in our case is hard, never amended clay.
My question is: how can we turn the sand/clay into good, workable garden soil? Do we need to remove all the sand? Can we leave some, layer it with compost and rototill?
What is the most labor effective solution?
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Post by spike on Apr 1, 2024 18:55:04 GMT -5
We had an above ground pool and when we took it down we had a huge circle of sand also. Got a load of fill dirt and tilled that mess up. We also have clay soil (>,< Could make adobe bricks or throw pots). Once that mess was tilled up, we made that our wild flower bed. Works great for us.
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Post by Laura_in_FL on Apr 1, 2024 19:19:07 GMT -5
What is the drainage like from that spot? Since you have hard clay under the sand, I am wondering if your yard drains away from or towards that part of your yard. As long as it doesn't drain towards that area you should be all right. If the yard does drain toward that area, you might end up with a pond there after heavy rains or in spring when snow melts. That's bad for most plants and I don't really have any experience dealing with that kind of drainage problem. Many veggie plants are perfectly happy in sand as long as you can get enough organic matter and nutrition into it. That's good - otherwise everyone in Florida would starve, because in many places we have basically beach sand that is tens or hundreds of feet deep! Don't get me wrong - a nice loamy soil is best. But sand works just fine to grow plenty of stuff, it it's sufficiently amended. 8'-10" of soil is plenty deep enough for most veggies - many people grow in raised beds that are that shallow. I would say that if you can get enough compost for cheap or free, just till a whole bunch of it in and plant. Like 3"-4", or even a bit more if you can get it. Remember the sand used under concrete slabs has basically ZERO nutrition or organic matter in it. Water drains through it fast, too. So you'll want a bunch of compost the first time to add the nutrition and helps it hold on to moisture longer. In future years adding 1"-2" is probably sufficient. You might also look into getting and tilling in some biochar just once. Biochar is supposed to be amazing in sandy soils, because it helps the sand to hold onto the nutrients and organic matter longer. But if you're used to gardening in clay, be prepared to have to water more often, even with the added compost. If you're going to use a row garden for vegetables type of set up, you only need to add the compost to the rows. There's no need to amend the pathways. Just keep the paths hoed, mowed, or mulched. Amending only the rows will cut down on your cost and labor. If you cannot get enough finished compost for cheap enough, you can also sheet compost raw (not composted) organic materials right on top of the sand. Layer "green" and "brown" materials right on top of the soil. Each layer should be a couple inches thick, be sure to alternate "green" and "brown", putting the coarsest materials on bottom and the finer stuff on top. You want to pile up at least a foot worth of organic materials. Raw manures, straw, grass clippings, rotten veggies/veggie scraps (from grocery stores or restaurants), fallen leaves, or whatever you can get your hands on for cheap or free. Or if you can get ramial wood chips for cheap or free (through ChipDrop or some other source), pile them up at least a food thick and let them rot down; that's the "Back to Eden" approach. Note that for the "Back to Eden" method to work you need ramial wood chips - the kind from fresh tree trimmings that have lots of shredded up green leaves and twigs in them. Ramial wood chips are pre-mixed green and brown material, containing both nitrogen and carbon compounds. So ramial wood chips will decompose into basically compost. But the kind of wood chips sold for mulch/landscape use are brown material only. They are either bark or wood from trunks or large branches. Those brown-only chips don't have any nitrogen, just carbon, so they will rot slowly and won't nourish your soil the same way. Also, you need to spread a foot or more of ramial wood chips the first time. In subsequent years you can top off with 4"-6" or so. The downside of either sheet composting or using ramial wood chips is that you may have to wait out this growing season while you wait for everything to rot down. Though I would test plant some things right away, right into the sheet compost or wood chips. Some veggies will grow in what is basically an active compost pile. (In a perfect world, you'd have done your sheet composting or spread your ramial wood chips last fall so they could break down over winter; then the soil would be ready for planting this spring.) Anyway, those are just some ideas off the top of my head for using that area as a veggie garden. Hope it helps! I'll be interested to read what others suggest as well.
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Post by Laura_in_FL on Apr 2, 2024 11:16:54 GMT -5
spike, the reason I didn't suggest using fill dirt at all is that the quality of fill dirt is highly variable. One time I got really nice fill dirt, but more often the fill dirt we get around here is NOT an improvement over the sand we already have. Sometimes it even has rocks, woody debris, or even trash in it! octave1, if you can see the quality of the fill dirt in advance and know that it's decent stuff, that could be a viable way to improve your sand. Especially if you're intending to grow grass, wildflowers, or ornamental shrubs and trees.
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Post by spike on Apr 2, 2024 16:24:31 GMT -5
spike, the reason I didn't suggest using fill dirt at all is that the quality No worries! Considering that we have clay soil around here, we can get amazing sifted fill here that is great. Plus there are so many places selling loads of dirt, they sell the "good" stuff or lose to much business. ESPECIALLY if it is gardeners they are selling dirt, cause we will rat out bad landscapers in a heartbeat!
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Post by mgulfcoastguy on Apr 3, 2024 18:18:56 GMT -5
You could plant either hemp or daikon radishes , both are known for breaking up clay soil. If you plant the radishes just mow the tops off come fall and leave the roots to rot in place. Or a load of partially composted horse manure and hardwood leaves over the top and let the worms move in and start breaking it up.
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Post by brownrexx on Apr 17, 2024 8:32:44 GMT -5
I will be facing this sandy soil issue myself in a few months since we close on our Florida house in 2 weeks. However due to my upcoming knee replacement, we will not be moving until the beginning of July. When we walked around the property it was as Laura_in_FL, described - beach sand with grass that is called Bahia but looks like our crabgrass. I am planning on a couple of raised beds to start my Florida gardening adventure but here in PA I have planted daikon radishes as mgulfcoastguy, mentioned with really good results. They get absolutely HUGE and go down deep to break up the clay and bring up nutrients from below. In our climate the frost will kill them and the radishes just add to the organic matter as they rot over the winter. If I were you I would probably just roto till in a bunch of organic material and then maybe plant some radishes. There is a particular variety of daikon for this purpose called ground hog radishes and they get bigger than regular edible daikon. The ground hog radishes are sometimes used for animal forage but I don't think that they would taste very good to humans. They look like they would be tough.
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Post by mgulfcoastguy on Apr 17, 2024 11:46:26 GMT -5
spike , the reason I didn't suggest using fill dirt at all is that the quality of fill dirt is highly variable. One time I got really nice fill dirt, but more often the fill dirt we get around here is NOT an improvement over the sand we already have. Sometimes it even has rocks, woody debris, or even trash in it! octave1 , if you can see the quality of the fill dirt in advance and know that it's decent stuff, that could be a viable way to improve your sand. Especially if you're intending to grow grass, wildflowers, or ornamental shrubs and trees. Fill dirt is a loose term for dirt used to "fill in low places" or even to start on building foundations. Top soil is much more specific. It typically has a requirement for a certain percentage of organic matter and a ph range. That means that it is more expensive. To meet that regulations for off site hauled in top soil where I worked it typically had to have organic matter mixed in to be able to pass the burn off test. More work=more money.
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Post by Laura_in_FL on Apr 17, 2024 12:57:44 GMT -5
Yes, like others have suggested, cover crops can be a big help. Tillage radishes to break up the hard clay beneath your sand, and other cover crops to add nitrogen and biomass. Using cover crops can save you from hauling in massive amounts of compost, wood chips, etc., to get started. I know the link here is for a seed company, but their article on cover crops is really helpful in choosing cover crops for specific needs (so they can sell more cover crop seed!): www.americanmeadows.com/content/clover-grass/how-to/choose-cover-cropsThe key in the long term will be continuing to add organic matter and keeping that sand covered either with healthy vegetation or thick organic mulch all of the time, especially in the summer. Organic matter bakes and leaches out of uncovered sand quickly. That process probably does not happen as fast up there as it does down here, but it still happens pretty fast. So don't leave the soil open and fallow at any time, even over winter. If you like, you can till under the garden once it's done in the fall, but then cover it with a thick organic mulch or plant a quick-growing fall cover crop that will winter-kill and leave the dead cover crop in place until shortly before planting time in the spring. Just remember: bare sand is bad! Keep the sand full of living plants or under a thick organic mulch at all times so you don't undo your hard work improving it. And with regard to organic matter, unless it's full of pernicious weed seeds or roots of root-propagating weeds, don't remove organic matter. Till it in or cover it (if you're doing a low-till or no-till system) and let the organic matter rot in place. Or gather the organic matter and compost it, then put the compost back into the soil. I feel like a hypocrite talking about this, since I am not doing it at my own property! But I learned last year that until I get a watering system in place at my new property, any cover crops are just going to die in the annual spring and fall droughts. (We are hauling buckets of water from home to keep the fruit and pecan trees going.) Even 99% of the wildflowers that I planted last year died in the late summer/fall drought. They have been replaced by Spanish Needle and a few other very drought-tolerant local grasses and weeds. So until we get the well and pump going, I am acting like one of those annoying "do as I say, not as I do" parents. In the meantime, I have let the native weeds and grasses take over the future vegetable garden; the native plants will at least keep some life in the ground (bacteria, fungi, bugs, worms) so the sand doesn't go completely sterile.
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Post by Laura_in_FL on Apr 17, 2024 13:25:04 GMT -5
spike , the reason I didn't suggest using fill dirt at all is that the quality of fill dirt is highly variable. One time I got really nice fill dirt, but more often the fill dirt we get around here is NOT an improvement over the sand we already have. Sometimes it even has rocks, woody debris, or even trash in it! octave1 , if you can see the quality of the fill dirt in advance and know that it's decent stuff, that could be a viable way to improve your sand. Especially if you're intending to grow grass, wildflowers, or ornamental shrubs and trees. Fill dirt is a loose term for dirt used to "fill in low places" or even to start on building foundations. Top soil is much more specific. It typically has a requirement for a certain percentage of organic matter and a ph range. That means that it is more expensive. To meet that regulations for off site hauled in top soil where I worked it typically had to have organic matter mixed in to be able to pass the burn off test. More work=more money. Huh. The "top soil" around here is better, but not much better, than the fill dirt! Maybe there are different regulations for top soil in different states? The builder sand that is used under foundations here is different; it's a very clean white or off-white sand with a particular percentage of specific grain sizes so that it can be compacted to a particular load-bearing capacity. (Florida building codes are pretty specific about what soil you can have under a foundation.) Builder sand also drains VERY fast, much faster than the fine sand at my property. There are some areas in my county where the builder sand is the natural sand, and some of the deposits of that kind of sand are very deep. One of those areas is the "sand quarry" where local contractors get the sand to use under foundations. But there are scattered areas of it across the county. It pretty much only grows pines, palmettos, bahia grass, and a few scrub oaks; even most of the native deciduous trees struggle to survive in that stuff. Yes, some folks have even less fertile sand than mine!
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