Can 7000 m² of agricultural land be rezoned into building land?

Yes, it can come to that. Of course. It's just speculation.

I thought I could look at some key data to see if the area might eventually be suitable as land expected to be developed.

At first glance, it doesn't look like it on the map. By the way, building land is currently becoming cheaper again, as this is still the only factor to negotiate house/apartment prices downward. From my experience, you can gladly buy the plot. But don't worry that it will become building land in the next 20 years. Cities and municipalities are increasingly linking development plans with urban development contracts. This means the infrastructure development costs are passed on to the one who wants the development plan. So laying supply and disposal lines, building roads, green spaces, possibly playgrounds and kindergartens, etc. From the 7,000 sqm, only 5,000 sqm will eventually become building land; the rest will go towards the above-mentioned points. If you have the money, you can bid. The price probably can't be high; a car likely costs more. BUT: Langeln with around 500 inhabitants will, in my opinion, 100% never allow such a large area to be developed as building land — because then surrounding plots would also have to be included — it would mean doubling the population overnight. Who would want to move there?

5000 sqm are 5-6 plots of land in the countryside. How do you double with that?

In a forced auction there is of course an appraisal and if there is even the slightest possibility of a building area, it must be stated in it. Otherwise the appraiser is liable for damages. If a municipality does forward-looking land planning and has plans for it, it buys the land itself. If you are young and can wait 30-40 years and have the money left over, you can buy.

5000sqm are 5-6 plots of land in the countryside. How does one double that?

Because the times of excessively large plots are over. With such a large area (it’s not only the TE’s parcel that is included) there will have to be multi-family houses alongside normal single-family houses – keyword social housing / price-dampened housing. From my professional experience, I gladly see quotas of 20-30% in rural areas up to over 50% in urban areas. Apart from that, I rather don’t see a real new development area out there – in the middle of nowhere. 10-15 km to the nearest highway, no shopping facilities, no kindergarten/school, no gastronomy. Instead, farmers, an aging population, and maybe an occasional village festival. Where the main street is already called village street and the community consists of about 50 houses, there is no need for a large new development project. But yes, one can buy the plot. And then lease it to the countless agricultural businesses.

Our new development area has 20 plots on 16,000 sqm. Remaining per plot are 600-650 sqm. In towns with 500 inhabitants, no one wants to build residential silos. However, I don't really see this as a future new development area here; I would rather connect that in the northeast than directly on the railway line.