What is this "topsoil" you are contemplating spending money on? "Topsoil" is simply the top 4 to 6 inches of soil from someplace and can be anything the seller wants it to be. Many people think "topsoil" is loam and it is not.
Why not add organic matter, and that manure tea to the soil you have now? What do you think is wrong with the soil you have now that you need to buy something called "topsoil"?

Well, the soil I have now is very shallow, because here on the Big Island Of Hawaii (ZOMBIE LAND), the ground is rock, so I had them deliver CINDER SOIL, then after the rains, it settled into thin layer, so I think I need some depth. For fruit trees, I had a huge tractor drill holes, but I'd like to make some beds with depth.

Thank you for asking.

Have you tried asking this on the Hawaii Growing forum here? You might have more luck....or the tree forum? Just a suggestion! Nancy

You have conditions there that are quite different from the continental US, so we might not be of much help. What kimmsr is getting at is amending and improving your existing soil. If it's too thin and there is rock underneath, I can see how you would want to add more. Whatever you decide to use, adding ample organic matter will help improve it in various ways. As for chicken manure tea, I think I would mix in the chicken manure directly, if you're not going to plant for a few months, or compost it and add the compost. Tea will add microbes and some nutrients, but it's more of a quick acting tonic for plants rather than a long term soil improver, IMHO. After planting you can also add organic mulches (shredded wood or yard waste, leaves, almost anything) which will decompose and continue to improve the soil without disturbing tree roots.

Soil is made up of the mineral component (the sand, silt, and clay) and organic matter, (vegetative waste). In sandy soils that organic matter fills in the pore spaces and aids in holding both moisture and nutrients in the soil. In clay soils that same organic matter separates the soil particles so the moisture, nutrients, and plant roots can move about with greater ease.
If the "topsoil" actually does contain the 5 to 8 percent organic matter a good soil should have and you add that to the soil you already have the amount of organic matter is diluted quite a bit. Add enough organic matter to the soil you have to bring the level to that 5 to 8 percent level and forget adding more of the mineral component which you do not need

You can make sterile quartz fertile by timely applications of your chosen fertilizer. And if you really want to brew chicken manure tea, it will do the job. I'd cheat if it were me and just add the chicken manure.

As to what to get, topsoil or the cinder/soil, that's your call. If you've used one and not liked the results, get the other. The worst that happens is you learn something.

Ty Strob..

Many years ago I wanted to plant fruit trees. We have only about 6" layer of soil and below that is pure shale rock. I was at that time advised by the fruit tree nurseries to dig holes, fill them with good dirt (compost etc) and plant the trees. That is what I did. With great deal of labor we dug holes about 4 feet deep and 4 feet diameter and planted several fruit trees.

Result: The plants grew fine but when came time to bear fruit 2-3 years later, the fruit was sparse. Over the next 10 years, the trees did not flourish at all and slowly became prey to diseases and died. The consultations with experts over the years suggested that "just digging a hole does not help, beyond the 4 feet the roots cannot go any where and therefore the trees remain weak".

The Hawaiian rock I understand is lava rock and therefore more porous. Not sure if that may be different.

Thanks for all answers. Stuff seems to growclike mad here, even in holes, possibly due to some minerals in lava.About the only positive thing here is the nature, lol.

ju, I had the same thing in my heavy clay soil!
We dug (when we could) added a BUNCH of compost to the hole and the area, the Fuji tree grew great for 2 years, then died! When we dug it up, all of the roots were still in the original hole we dug! They couldn't penetrate the clay soil!
Other trees have perished and only a few have done fine in this yard (Japanese maple and Oak). In the back yard, We planted a Mimosa and a black locust that have done fine! Nancy

About 25 years ago, or so, some of us discovered that just amending the planting hole created many more problems then it solved. Adding lots of organic matter to just the small area something will be planted in, whether clay soil or sand, or volcanic, changes how that soil handles water and result in the drowning of the plants.
Organic matter needs to be added to the whole area to be planted, not just the planting hole.

Kimssr, your last post is interesting, but..what is the mechanism? TY

Organic matter acts like a sponge, soaking up water and often holding it in place which then excluders the air plant roots also need. The mineral component of soil, the sand, silt, and clay particles, do not hold any moisture, although the size of the particles (clay) can impede the flow of water.
Adding large amounts of organic matter to a planting hole can change how water flows through that soil and can make it easier for that water to flow in but not out, resulting in waterlogged soil where plants drown.

Osmosis! Thanks.

Clay is notorious for this. Dig a hole, and it wet weather water will seep out of the walls and sit in the hole even if you had it covered. It does not drain out very fast though. If you fill a hole with very porous soil - like mixing in a lot of compost or peat - it will do the same thing and all the pores will fill up with water and it will sit there. In wet weather this can rot the roots, and there isn't much incentive for the roots to penetrate beyond the hole, which is also bad.

Not that this happens for every tree in every case, but it can be a problem.