Soil survey before purchase or before construction

Hello, what you can do in two weeks is find out what was on the property before. If it was previously farmland, a farmer can surely tell you about the soil conditions, if there was a gas station or other business before, I would be careful.

It used to be farmland, still borders directly on the field, and according to a neighbor, it is clay soil with a few stones no bigger than a fist. Is this now a good or bad soil for building? We don't want a basement....

Even if you know the exact location of the future house, this is only a risk reduction. Only points or drillings are checked, not areas. With bad luck, you can still encounter a surprise between two drilling points. So, with similar accuracy of the result, you can simply roughly estimate where the house would stand and commission two drillings with a 10m distance (just an example). The goal is at least generic statements about the subsoil to gain an indication of whether a cost explosion is lurking (poor soil composition, high groundwater, rock near the surface when a basement is desired, ...). Your geologist will advise you on what makes sense.

It was previously farmland, still borders directly on the field, and according to a neighbor, it is clay soil with a few stones no larger than a fist. Is this now a good or bad soil for building? We do not want a cellar....

There will be no general answer. As already mentioned, it depends on whether you are building with a cellar (groundwater, rock horizon) or not. We bought our plot without a prior report but received one from the municipality that was made due to development. If you buy in a new development area, your municipality will surely have a report and will provide it to you. Although it is not suitable for your house construction, it does give a rough overview.