Rustic land is a type of “Suelo No Urbanizable”
Non-Urbanizable (Suelo no urbanizable): This is a land considered no-urbanized. It means that the land classified in this way cannot be urbanized. So no urbanizations, cities, or plans can be developed in the area.
There are a lot of type of land included in this classification, like green areas, protected areas, mountains, lakes, public areas, etc.
Inside this classifications there is the “rustic land”. This is a land which must be used to grow for farmers. So the only use allowed in this land is to “grow”, or to be used by farmers to develop an agricultural activity.
But, in this land, it is authorized to build new constructions, eventually. These constructions must be in a very low density of construction. So, is very common to find that only when the land has a minimum size (5.000 m2 in Murcia, passing to the 10.000 m2 in the Spanish Land Law (Ley del Suelo), or 20.000 m2 in over protected areas), you can build there an individual farm construction, also called “cortijo”, “villa”, “masía”, chalé”, “chalet”, “hacienda”, etc.
Of course, there can be houses in rustic land over plots smaller than the minimums required in the different areas. This is because these buildings were built before the new regulations entered in to force, or simply that they were built “illegal”. In these cases, these houses are respected by the public institutions (unless they were built illegal and the file of the infraction has not been expired) and can be reformed, but not extended.