This response was provided by Darryl Coates, Illinois Department of Natural Resources District Wildlife Biologist.
Good morning, It is very difficult to dissuade geese from getting from water to crop as you have already found out. This web site has recommendations that may be used to assist you in this endeavor. I often tell my cooperators "With geese, you must use several of the following recommendations to slow down or stop the depredation of your crops. There are no easy fixes in this situation." Use three to five of the following recommendations to slow down or stop the damage. Habitat Modification: Sign up your land in C.R.P. filter Strip - plant trees, shrubs and/or tall native warm season grasses around lagoons from waters edge to 30 feet (min.) and limit mowing. Exclusion: build trip lines or use poultry wire at the water edge. Depending on the size of the lagoon - create a 12-inch X 12 inch grid using 20 lbs. fishing line over the pond surface about 8 inches off the surface of the water. Frightening devices: dogs or cracker shells (non-lethal harassment). Taste Repellants: spray RejeX-it or Flight Control on soybeans in June. To read more, go to Damage Prevention and Control Measures by Right clicking: Wildlife Directory, Birds, Bird Species, Waterfowl, Canada Goose. Scroll to heading above for details. Thanks for writing.