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I made a stupid mistake that has ruined my garden which I didn't realize until now. When moving in to my current house years ago, I tried to "improve" my garden soil by removing lots of soil and adding lots of free sewage sludge "compost" from my county. My garden has always been non-productive, especially for fruit trees, even though I have supported it with excellent materials from two big compost bins. I think my soil lacks sand and clay to support the root systems of the fruit trees (about 7 feet tall on average). I tried the test in the link below, but only observed one layer. I think the sandy and clay layers are missing! Does anyone have a good suggestion to fix this problem? Hope I don't need to hire a company to replace the soil. Any suggestion or thought is much appreciated.

https://www.todayshomeowner.com/diy-soil-texture-test-for-your-yard/

Jon

  • You can buy garden soil in bags, they contain sand and clay. – benn Jul 6 '18 at 7:10
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    Number one most gardeners learn is that we do not change our soil, we learn how to manage it. Clay, sand are just PARTICLE sizes of soils that have inherent properties. Compost of any kind is NOT SOIL. Decomposed compost is best dumped on the surface of the garden allowing the micro and macro organisms in the soil EAT this decomposed organic matter, they go back into the soil profile and poop it out mixing it for you. Works beautifully. There are no such things as Sand LAYERS or Clay layers. Our soils are a mix of sand, silt and clay with organic matter as the top layer. – stormy Jul 6 '18 at 8:06
  • Call your nearest Cooperative Extension Service if you live in the states. Please send pictures, amounts you added, how they were mixed, how deep is this fake soil? – stormy Jul 6 '18 at 8:08
  • @Stormy - the layers the OP is referring to are those found in the soil test that he linked to, which is a standard jar test, often used with the soil pyramid (as it is in the link). – Jurp Jul 6 '18 at 13:31
  • When you removed the soil, was it just off the top layers? In other words, the topsoil? How deep was the layer you removed in measurement, roughly? – Bamboo Jul 6 '18 at 15:11
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You say you removed about 1.5 feet of soil from the top in your garden; that means you removed all the topsoil, possibly some of the subsoil too. Topsoil varies in depth from 6 inches to 2 or 3 feet, regionally round the world.

I'm afraid the best thing to do is to buy in a large amount of good quality topsoil (probably by tipper truck depending on how large the area is) and spread that over the garden to replace what you removed. A depth of 1.5 feet of topsoil is fine, even if you stripped out some subsoil previously - if you had done so, subsoil is usually of a different colour and texture and you would have noticed that at the time. Topsoil is very important - it's the layer that contains humus material and is full of soil organisms, in other words, it's fertile. And yes, after that's replaced, emendments such as composted manure, garden compost and so on can be made to that, to keep it in good condition ongoing.

If you no longer have room for 1.5 feet of topsoil, so long as you spread a layer that's 9-12 inches deep, that should work.

  • 1
    Thanks for the reply. I have two more questions. First, do I have to remove the current fake soil before adding new topsoil? Second, for areas that I am going to plant small trees, is topsoil of 1.5 feet depth good enough? Should I dig a 3 feet hole, for example, and then fill in topsoil? – Jon Jul 6 '18 at 21:40
  • if the current 'fake' soil is 1.5 feet deep, you may have to scrape it off, add topsoil, and then mix the 'fake' into the topsoil if you like, but since what you appear to have used is humus rich, it should have decomposed significantly and be a much thinner layer. 1.5 feet of topsoil is doable for trees - there's a roof garden in London UK with a soil depth of 18 to 24 inches and there are tall trees growing in it. – Bamboo Jul 6 '18 at 21:55
  • Thanks, Bamboo, so much for the information. It's a painful process to correct a previous mistake. I have to replace the soil again. I feel that I need to be an idiot again. But, this time, I have knowledge shared by you guys. Thanks a lot. – Jon Jul 6 '18 at 22:44
  • Most roots only grow in the top 4 to 6 inches. Roof gardens are similar to growing in pots using major drainage systems. But using HOT or even decomposed sewage sludge is no replacement for soil soil. And it needs to be mixed and compacted. I love this question, it is a worthy conundrum! – stormy Jul 7 '18 at 1:39
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https://www.reference.com/home-garden/soil-fertility-fd6838fde6db1eea#

I am worried about a layer of soil spread over your 1.5 feet of compost. This is kind of upside down.

A normal soil has horizons; the very first one is mostly pure organic matter in some stage of decomposition, leaves, twigs, rotting logs. The next horizon is topsoil. Mostly a few inches deep. Then there are the alphabet labelled layers down to bed rock.

When there is decomposed organic matter sitting on top of the top soil, the organisms in the soil wake up, come out of dormancy, climb up to the surface to eat this decomposed organic matter, whew, I am going to call this DOM for short. After eating, the micro and macro organisms then go back down into the soil and poop it out. This mixes the DOM into the top soil better than we humans can do.

The majority of soil life only lives in soil that has air. Compacted soil or water logged soil starts using a different process that is anaerobic. Most plants have evolved to thrive in aerobic soil ecologic systems. DOM keeps pore spaces open and able to be filled with air. As important to clayey soils as it is to sandy soils.

Subsoils are compacted, lack air. Depending on the soil type, soil life is limited as well as DOM. What little 'fertility' or chemistry plants have to have (to photosynthesize and make their own food/carbohydrates) that might have made it past the hungry decomposer community and leaching would actually wind up in the subsoils, not the topsoil. Kind of interesting.

If there is little to no decomposed organic matter at the surface, life in the soil goes to sleep, goes dormant, dies until there is decomposed organic matter available at the surface. Once there is decomposed organic matter, DOM, the 'food' all the other non decomposing organisms eat...the life revives, reproduces and the soil is better for plants.

If you go and get soil out of some virgin forest or even from a rain forest in the tropics, that soil is going to have very little if any 'fertility' or chemicals that plants need to grow, reproduce make food for us humans and food animals. Most of all the chemicals plants need to uptake for photosynthesis to take place is locked in the live biomass. Really helps curb population growth of plants. Nature adds just enough to the soil of an established ecosystem through decomposition of organics to allow perhaps ONE new plant to be added or allowed into the ecosystem. Nature isn't into mono crops and efficiency of bushels per acre. There is never the correct amount of fertility in any soil unless we humans try to figure it out and add it to the soil in just the correct amounts; concerning fertilizer my dumb ditty is : Less is best, More is death and None is dumb. Fertilizer is in no way plant food, plant nutrients...just chemistry and we have to put our lab coats on to understand how this works. Just a little too much and it is death for plants. When a gardener has become experienced, they are able to SEE the symptoms of excess of a chemical, lack of a chemical and when everything is just right. I fertilize usually only when I see a deficit. I check the pH of the soil in pots and all garden soils.

Everything we humans touch is artificial. The closer we can stay towards using indigenous soils, indigenous plants, learning how to manage those resources correctly the better our crops will grow. Potting soil is sterilized and contains amazingly very little soil if any soil at all. Sounds a bit like your soil; you made a pot or maybe a 'swimming pool' (this is what I've imagined) and filled it with unsterilized, possibly raw or hot organic matter. Too much nitrogen. That will kill trees, certainly. Drainage is suspect. Swimming pool needs drainage.

It would be nice to have a picture of the bottom of this...swimming pool. Do you remember what that soil was like? What are your plans? A landscape or vegetable garden? Adding balanced fertilizer is a must. Compost, unless hot doesn't add but miniscule bits of Nitrogen.

When something is being decomposed the decomposers are an entire community whose job it is to decompose EVERYTHING that dies, immediately. They are in the soil, on our skin and in the air. They are everywhere and they use Nitrogen for energy to do their work. They have first priority. The decomposing community have dibs on any Nitrogen available before plants get the left overs.

As long as we still have stores and the internet, I will always buy a balanced fertilizer from the store. Cheaper than soil tests, I have a very good idea what is in my soil. I have added decomposed and aged horse manure as a winter cover. The soil organisms do the mixing all winter long. I make sure to use a lower percentage of Nitrogen in the fertilizer for the next season's crops.

An initial professional soil test is gold. Whatever one adds to the soil from that point on will be calculated based on that initial test; either added to the numbers for your 'fertilizer' program, subtracted (adding non decomposed organic matter such as chips or straw is a subtraction from any balanced fertilizers added). A second soil test a year or two later will quadruple the benefits you get doing the soil tests.

That will tell you whether or not your fertilizer program needs changing (build up of too much phosphorus for example, no nitrogen or potassium left over for the next crop).

I am worried that your compost with a foot of soil over it will become a stinky swimming pool of stagnant mud or it could be the reverse. Your compost could cause a 'perched water table'. An upside down perched water table. Whatever type of soil spread over the compost would not be able to drain well and that would keep that layer of soil wet and mushy. The fine pore spaces of the new soil over the large fluffy pore spaces of the compost would cause any water drainage in that soil to stop at that barrier until the entire layer of new soil is saturated. Then the water will begin to drain into the compost. Filling the swimming pool? Need to SEE what you've got and first thing I'll be looking for is negative drainage away from this 'swimming pool' how to accentuate that drainage and make it legal?

I apologize for length of this 'non' answer. I am thinking through the different scenarios your 'boo boo' made. Seriously interesting. I've never seen this problem in real life. It is amazing though because people really need to do the 'right' thing, get lots of 'wrong' advice and few give up before they remove 1 1/2 feet of 'top soil' and fill with compost. You've done this and my brain is working over time. I would love to hear the Master Gardeners at the Co-op trying to figure an answer. You have to let us know what they say. I'd like to save you any more major work and dough. Do you have a friend with a backhoe familiar with a backhoe insured to use a backhoe? Have you used a rototiller? (Mixing). Also will need (sounds odd by now but) a compactor. I've no idea the size of this project but at this depth and percentage of DOM, you might need a road compactor.

  • I've been trying to make an answer while we've got cops running around sneaking up on our neighbors. Always check the neighborhood before you buy a home. Ugh. Meth houses, raids with bullhorns cops parking on our land which looks like WE turned the neighbors in, we were squealers...ugh!! And we live in the boonies. – stormy Jul 7 '18 at 2:16
  • I don't know how post files here. Instead, I post pictures and a video to the following google link: drive.google.com/drive/folders/…. – Jon Jul 9 '18 at 6:56
  • Thanks, stormy, so much for the kindness. Your knowledge sharing is really appreciated. As you can see in the pictures, my garden is small and the fake soil is easy to manage. I will probably just remove the top 1.5 feet soil and then add garden soil from a store. That is the easiest solution to fix my previous mistake. – Jon Jul 9 '18 at 7:03
  • Loved your pictures. What will you do with what you've removed? Add topsoil after removing the compost then put at least 3 inches on top. Keep the rest in a pile close by to add later. If you plant, plant starts. Remove the compost for the sections you'll be planting seeds. When plants are 6" or more higher, start adding thin layers of compost to the top of the soil. Add a balanced fertilizer at least half of what the direction direct. Check around for 'top soil' delivery. Don't use bagged soil, this is a garden out of doors. Compact with a water filled roller. – stormy Jul 9 '18 at 8:49
  • That is very insightful. To clarify, could you confirm my understanding of the first few steps? 1) Remove top 1.5ft soil 2) Add 1.5ft of new top soil 3) Add 3in of original compost removed in step 1 Thank you. – Jon Jul 10 '18 at 7:17

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