We conduct models and tests to ascertain whether there are speculative bubbles and which factors contribute to the bubbles if there exits one. In the model, we use the option value to represent the investment value of farm real estate and compare the option value, calculated from dynamic programming, with the actual farm real estate value to conclude whether there is a speculative bubble. In the test, we use robust regression analysis to ascertain the factors that contribute to the bubble. The result shows that there are two major speculative bubbles from 1976 to 1983 and 2003 to 2011 in Iowa State with the Iowa State data from 1950 to 2011. The factors contribute to the bubbles are corn price value, farm debt to asset ratio, direct government payment, net farm income and its percentage change, real farm value percentage change, urban land to total land ratio and production cost.