Water Retention Curves

[camh]

I know water retention curves for different soil types typically follow this trend (top figure), where generally as soil moisture decreases, water potential increases. However, I was wondering if there could be a case where water potential actually increases temporarily as soil moisture increases, as demonstrated by the shape of the equation in quadrant I of the lower figure. (I.e. can the presence of roots in soil increase water potential as soil moisture increases? Or some type of additional external force that increases as water content increases?)