Peasant farms were in early Modern Times subjugated landlords, mostly Crown estates, nobility estates, and after the introduction of absolute monarchy also commoners. In order to gain right of use of the farms, the peasants had to render a number of fixed taxes, once-for-all payments as well as work obligations. The subject of this Ph.d.-thesis concerns the fixed taxes, the land rent, typically paid in agrarian products.

The land rent must be seen as stemming from the production at the time of fixation, and the entire idea behind payment in agrarian products was that the farms themselves could produce it. It is thus no surprise that some regions developed a predilection for certain types of products, and that we today can map these as region-specific products. The various products in the land rent, persiller, did not however reflect the production directly, as has been interpreted by several historians. The land rent was, on the contrary, a particular selection of the production where, in particular, two criteria played a role: 1) the financial interests of the landowners in obtaining products which matched the possibilities for sale and export, and 2) the peasants' wishes only to pay land rent in products remaining when their own consumption and future farm production had been catered for. The agrarian historian Svend Gissel's use of the term funktionally conditioned land rent (1968), where the types of persiller should reflect the utilisation of a corresponding adjoining land, can thus no longer be seen as being valid. It would be more correct to use a term such as the selective land rent in order to underline that the land rent was a selected part which did not necessarily correspond to the dispersion of elements of the entire production of a farm.

The size of the entire land rent did, naturally, relate to some extent to the available resources, and the level of land rent was generally high in areas with ample and good resources. However, the more the source material is studied, the clearer it becomes that the land rent could be rather unjust. The land rent was settled locally and over a long period of time, and thus not necessarily based on a uniform set of rules. Already at the time of fixation there could be differences from region to region and from farm to farm. From the late Middle Ages the land rent was fixed in spite of changes in acreage and improvements carried out in some regions. The farms who were best of and which had the relatively lowest land rent were situated in regions which since the fixation had the potential for expansion - particularly by means of land reclamation, which gave a much higher yield by acreage. On the contrary, the farms situated in regions hit by sand blow had some of the relatively highest land ret, as their resources had diminished considerably without the rent having been reduced to the same extent.