Yes that sounds about right. It takes multiple decades for some semblance of diversity to return to plowed fields. And it will never be the same as before. The

Yes that sounds about right. It takes multiple decades for some semblance of diversity to return to plowed fields. And it will never be the same as before. The soil biodiversity itself is massively degraded. You can speed up the restoration very significantly, assuming that is your plan, by doing mass native plantings and seeding. If you can introduce biochar before or as part of the process the soil biome will also recover much faster. Many resources online for all of this.