A method of drying a body of grain, the method comprising: storing the body of grain in an elongate bag silo comprising at least one wall of an impermeable material, a first end and a second end; providing at least a first arrangement of ports for air in the bag, the first arrangement comprising: - at least a first outlet for air from the bag, the first outlet being situated intermediate the first end and the second end of the bag; - at least a first set of inlets for air into the bag, the first set of inlets being situated intermediate the first outlet and the first end of the bag, the first set of inlets comprising at least a first inlet which is spaced a first distance from the first outlet and a second inlet which is spaced a second distance from the first inlet and longitudinally further away from the first outlet than the first inlet, and wherein the first outlet is the closest outlet to the second inlet in a direction towards the second end of the bag; the method being characterized in that the at least first arrangement of ports for air in the bag is provided in the at least one wall of the bag; and providing a flow of air in the bag, between the at least first and second inlets and the first outlet such that a pressure differential between any two of said at least first and second inlets is maintained within a predetermined threshold by spacing the inlets constituting the first set of inlets such that the magnitude of the first distance exceeds the magnitude of the second distance; and/or providing each of the inlets constituting the first set of inlets with a pressure regulating device. storing the body of grain in an elongate bag silo comprising at least one wall of an impermeable material, a first end and a second end; providing at least a first arrangement of ports for air in the bag, the first arrangement comprising: - at least a first outlet for air from the bag, the first outlet being situated intermediate the first end and the second end of the bag; - at least a first set of inlets for air into the bag, the first set of inlets being situated intermediate the first outlet and the first end of the bag, the first set of inlets comprising at least a first inlet which is spaced a first distance from the first outlet and a second inlet which is spaced a second distance from the first inlet and longitudinally further away from the first outlet than the first inlet, and wherein the first outlet is the closest outlet to the second inlet in a direction towards the second end of the bag; - at least a first outlet for air from the bag, the first outlet being situated intermediate the first end and the second end of the bag; - at least a first set of inlets for air into the bag, the first set of inlets being situated intermediate the first outlet and the first end of the bag, the first set of inlets comprising at least a first inlet which is spaced a first distance from the first outlet and a second inlet which is spaced a second distance from the first inlet and longitudinally further away from the first outlet than the first inlet, and wherein the first outlet is the closest outlet to the second inlet in a direction towards the second end of the bag; the method being characterized in that the at least first arrangement of ports for air in the bag is provided in the at least one wall of the bag; and providing a flow of air in the bag, between the at least first and second inlets and the first outlet such that a pressure differential between any two of said at least first and second inlets is maintained within a predetermined threshold by spacing the inlets constituting the first set of inlets such that the magnitude of the first distance exceeds the magnitude of the second distance; and/or providing each of the inlets constituting the first set of inlets with a pressure regulating device.