Large farms supposedly thrive on economies of scale, but there is a catch with the capitalist model used by large farms. When hit by a downturn or any unfortunate situation like crops ravaged by a storm, weak demand or overproduction, the farm takes a huge loss and often the recovery costs an arm and a leg. Small farms are better, they recover faster from any downturn, they can specialize with cash crops or staples and with the rise of farmer's markets even in urban centers, the delivery of product to market is most often more assured than large farm set ups.
