(Primary Reference: John Cook, Law and Life of Rome, Cornell University Press, c1967.) There were basically two types of tenantry - that on Roman Land and that on the Provincial ager publicus.
Roman Land Tenant ("Colonus"); Tenantry on Roman Lands was a matter of contract. There was no right in rem and no 'possession." There was no security of tenure and the period of tenancy was short, ( a lustrum of five years.) However, if the owner acquiesced, the occupation could be continued on a year to year basis.
Landlords often let their land with all farming equipment included. The tenant was required to cultivate and had a legal right to abatement of rent if an 'Act of God' destroyed crops. The tenant was required to restore the property to its pre-rental condition at termination of contract. The crops belonged to the landlord while growing and the tenant acquired ownership of the produce only after harvest. The landlord had an automatic lien against the produce for unpaid rent.
Provincial Land Tenantry: Most provincial land belonged either to the state as ager publicus or to the municipalities as ager vectigalis. Such lands were divided and surveyed on a grid system, (or "centurion,") and rented for a very long period of time or in perpetuity, conditional on rent payment. Tenantry rights became bought, sold and inheritable.
The Roman Emperors became the largest landowners, with a government department administering the leases and collecting rents and royalties for the Emperor's treasury. Leases on the Emperor's ager publicus were let to tenants-in-chief or contractors (conductores,) who sublet to "coloni." As part of their lease, coloni were annually required to provide several days of labor to farm the contractor's portion of the land. On marginal lands, coloni were given a heritable, and alienable perpetuity on the land, conditional upon payment of rent as a percentage of produce and labor on the contractor's land portion.