South Dakota law allows for oral leases for any size farm. The leases run from year to year.
The law includes specific provisions regarding oral leases for rental of farms that are 40 acres or more. By law, the oral agreement is a year to year lease. It automatically renews from year to year under the same terms.
The landlord must give notice on or before September 1 in order to terminate the lease or it will be automatically renewed. If the notice is timely, the tenancy terminates by law on March 1. However, if the tenant defaults (by failing to pay the agreed upon share of the crops, for example), then the landlord may give written notice later than September 1 and still terminate the lease.