When planting second crop beans into wheat stubble that ground can be very hard - I would recommend two Curvetines per row. In hard ground the rubber casn hold the Curvetine up from where we would really like it to run. One rubber + one Curvetine is usually the way folks start in worked ground.

However one will help a lot - you could go with one per row except use two per row on the end rows.... 

O'Malley's JD has several stores in 2nd crop bean areas of KS and should be able to give you the name of a customer who used Curvetines in similar conditions to yours last season.

Jim at Dawn