This is the way, initially we may use some magic numbers to enforce early rules till the network settles). The 1.5-2% is the figure regarded as close to population increase and more. The network will essentially calculate costs of resources to recycle coins for farmers to re farm. The supply / demand will enable this % recycle, which may be more or less what we initially think. Key is the network will decide based on resource availability. We do not want people involved unless absolutely necessary. The algorithms will have to be agreed though, well in my opinion. I think we can easily check and agree on the algorithm for fair distribution of resources, we can check if its right as well. If we get it wrong farmers will leave or not join.
HTH