This paper focuses on the possible paths -grain size and grain yield per unit area by which labor migration influences grain output, rather than the amount of labor migration, holds the view that if labor migration has an impact on food prcduction, mainly by influencing the grain size rather than yield per unit area. Subsequent empirical test has not come to refute this view. And this paper indicates that, during the period from 1978 to -2006, in terms of the absolute change in quantity or degree of contribution, changes in grain output mainly doesn＇t co...
