Bumper Crop is a pseudo realistic farming game on Facebook. One of the concepts in the game (and reality) is the edge effect. Permaculture is an approach to agriculture that mimics the relationships found in natural ecologies. In permaculture, the edge effect describes the heightened biodiversity and productivity among boundaries between vegetation zones. The game Bumper Crop simulates the edge effect by giving fields at an edge a 20% bonus. Edge effect requires level 13!