If its in your lease and the lease was signed by you and your landlord, its legal between the two of you.
It might not be legal if its unconscionable or its terms violate state statute.
The 48 hour term could be considered such.
Iowa provides a 72 hour notice provision under certain circumstances.
Your query does not relate to that.
But, even with the 72 hour notice, an eviction proceeding has to be held.
The 48 hour notice you inquired about is meaningless, anyway.
The landlord can't evict you.
A landlord can only ask you to leave.
If you ignore the request, then a landlord has to take you to court.
Only a judge can order you to be evicted.
You can ignore the landlord's 48 hour notice, should one arrive.
Then she would have to take you to court to evict you.
She has to follow the statutes to effect that request.
I wouldn't worry too much about the 48 hour notice provision.
I'd also keep my mouth shut about what i told you.
It isn't smart to tell the enemy about the arrows in your quiver.
http://landlordtenant.uslegal.com/lease/iowa-termination-of-lease-for-noncompliance-law/
562A.7 Unconscionability.
1. If the court, as a matter of law, finds that:
a.
A rental agreement or any provision of it was unconscionable when made, the court may refuse to enforce the agreement, enforce the remainder of the agreement without the unconscionable provision, or limit the application of an unconscionable provision to avoid an unconscionable result.
b.
A settlement in which a party waives or agrees to forego a claim or right under this chapter or under a rental agreement was unconscionable at the time it was made, the court may refuse to enforce the settlement, enforce the remainder of the settlement without the unconscionable provision, or limit the application of an unconscionable provision to avoid any unconscionable result.
2. If unconscionability is put into issue by a party or by the court upon its own motion the parties shall be afforded a reasonable opportunity to present evidence as to the setting, purpose, and effect of the rental agreement or settlement to aid the court in making the determination.
http://www.rentiowa.com/tenantcenter.cfm?CID=24#7