I fly at a club with about 20 members and high dues. In order to make the club more affordable to others, some of us donate to the club to keep the dues from becoming even higher. Dues are officially $100 but several of us typically donate twice that per year. We believe that if we shared the dues equally, we would get few new members and some of our long-term members would drop out. The dues would get higher and higher for those who remained and eventually the club would implode.
In our case making donations has become a more-or-less permanent situation. In your case it would be temporary - just until the new field is paid off.