To start, they are planning on speaking with a real estate attorney before finalizing any deal .

Someone I know is looking at purchasing a piece of land(Land A),  located in Kansas.   This piece of land has a road to the north and that is the northern boundary of the land.  There is another piece of property(Land B) to the south of land A.  This land appears to be landlocked but I can see from the county records that there is a small sliver of land that connects it to the road on the east. So there is access to Land B from the road to the east.   And that is the access that they have been using for the majority of the land for an extended period of time.

There is a creek that winds its way through this part of the county.   This creek runs through land B.   As such, the creek separates about 15 acres of land B from the majority of the land.   This separated portion has a small crop field on it. The current owner of land A has been leasing this orphaned portion and has been accessing it through his own land because otherwise it would be difficult to get equipment across the creek.   Maybe not impossible but it would be difficult without building a bridge or something.  

Is it likely that the owner of land B can force an easement or right of way through land A  for the purposes of accessing that orphaned 15 acres with equipment?   He already has access through the east and the creek can be crossed by foot.  

I guess the question is does the presence of the creek separating two parts of a property  qualify as something that would force an easement through a neighboring property in order to get equipment in there for crops?

As far as previous usage,  I believe the owner of land A,  which is the land that is for sale,  has been using his own property as access to get his equipment in to the orphaned 15 acres.

Disclaimers:
IANAL
state laws vary
anything is possible


IMHO, no, they cannot force an easement, they can access the property already, even if it is costly to build a bridge/water-crossing/culvert cost to install access that is already feasible is not a valid reason to force an easement.

That being said this is one of those questions that leans heavily on state law and legal precedent, they really need to talk to a real-estate lawyer.

I find it highly unlikely that a court would force a neighbor to allow access for a non-landlocked parcel, or portion of parcel, except in the case where the barrier is bona fide impassable.

FPNI has it covered with the extra notation that:
If someone already has and has been using access, there is a chance that access could not be taken away. If they can show a presidence of access it may be difficult to exclude that access by a new owner.
Also...if there is or was any legally granted access or easement it will show up on the deed. Maybe even an old survey. That is why you do your homework and get written documentation on everything before signing any contracts.