并列题名：Research on farmland input by farmer households in major grain producing areas Research on farmland input by farmer households in major grain producing areas 并列题名：Study on the issues of farmers' income in major grain producing areas 并列题名：Research on agricultural total factor productivity of major grain production areas Research on the farmland rights confirmation in major-grain-producing-areas 并列题名：Research on urbanization willingness and paths of the farmers in major grain producing area Study on the issues of farmers' income in major grain producing areas Research on agricultural total factor productivity of major grain production areas Research on urbanization willingness and paths of the farmers in major grain producing area