Why is this in my soil?

[NotAnEMERGENCY]

We moved here a year ago and I have been trying to loosen up the soil in my beds to prepare for new plants going in. When I pick up handfuls of soil and squeeze gently, the soil usually falls apart/crumbles easily. But I have also found odd lumps in the soil that just stick together and I'm not sure what this is.

Would I be right in thinking I should remove these lumps as I come across them? They presumably don't have any nutrients in them and are just taking up space that could instead be filled with something that is actually feeding the plants.

The lumps have the consistency of plasticine that hasn't yet been warmed up in your hands and is still reluctant to be formed into a different shape. Some of the lumps are the size of marbles but some can be about 5cm diameter. They are very light brown, almost yellow. The lumps are not just in one area but are mixed around all over both of my borders.

I really don't think it's clay soil as we had clay in our previous garden and that felt and looked quite different. As most of the soil crumbles fairly easily, I'm guessing it is mainly loam here.

The house was built 14 years ago so I assume that whatever is in the flower beds has been there no longer than that. Could it be that the builders added in something to the soil to bulk it out? Maybe to cut costs?

can you post a picture? could it be animal poo?

Sounds like clay. Probably dug into the top soil during the building work.

It sounds like cat poo

My first thought: cat poo.

If some are 5cm diameter I think clay is more likely than cat pop.Thankfully.

Unfortunately I do have some experience with cat poo. This is not the same. As Infinite said, the bigger lumps are not the right size/shape for cat poo.

For those of you who suggest clay, do you mean clay soil (i.e. nutrient rich) or something more like modelling clay, which I presume isn't good for a flower bed?

I could try taking a photo tomorrow.

I have clay. Sometimes you find a line of yellow clay. It’s grim stuff. I dig it out and shove it under the hedges.

Does it smell? Cat poo stinks. As does fox poo. You'd know, and, unless that cat or fox shat prolifically over a short period of time, much would (smellily) disintegrate if you squeezed it.

It's clay.

No builder would bother to add to the soil to 'bulk' it, and any bulkage would be cheap and would have disintegrated by now.

My guess is the builders chucked 'fine' topsoil on top of packed clay, the native soil, and over the years, bits of clay have been dug up and mixed with the fine topsoil.

When I find it, I squish it as finely as I can and chuck it around. Clay is good for retaining water and nutrients.

My suggestion is to not fight it. You can spend years trying to lighten it, digging it over, adding 'clay breaker' etc, but I'd put compost on it every year, mulch it well, and avoid plants that need free draining soil.

It’s clay, which has nutrients.

I'd say don't bother about what the existing soil is, you will find random lumps, clumps and stones in any bed not sieved or prepared to perfection (which isn't natural anyway).
I wouldn't worry about loosening up the soil either, plant roots grow in any soil type, you shouldn't need to do anything to the exsting soil to prep it.
I can really recommend Charles Dowding who does 'no dig' gardening principles.
He mainly does gardening methods and soil prep for vegetables, but the same principles can be applied to flower beds. I've done this for my beds and so far this year I have less weeds and better growth in my flowers than I've had in previous years.
There is a video series on YouTube which has lots of info: m.youtube.com/watch?v=f00IZ547PxE