A lowering force application system to an agricultural machine (1) having multiple row units (10), comprising: a first actuator (32), said first actuator (32) being arranged to apply a force to a first row unit (10), said first actuator (32) including a first descent chamber (33) and a first ascent chamber (35), the pressure in said first descent chamber (33) tending to oppose the pressure in said first ascent chamber (35)； a second actuator (32), said second actuator (32) being arranged to apply a force to a first row unit (10), said second actuator (32) including a second lowering chamber (33) and a second chamber (35 ) of rise, the pressure in said second descent chamber (33) tending to oppose the pressure in said second rise chamber (35), characterized by: a control device (320) of the first descent pressure in fluid communication with said first lowering chamber (33) for controlling the pressure in said first lowering chamber (33), said first control device (320) being configured to maintain, as a first selected lowering pressure, any of the continuous pressure ranges in said first lowering chamber (33)； a control device (320) for controlling the second lowering pressure in fluid communication with said second lowering chamber (33) to control the pressure in said second lowering chamber (33), said control device (320) being configured for second lowering pressure to maintain, as a second selected lowering pressure, any one of the continuous pressure ranges in said second lowering chamber (33), wherein said second selected lowering pressure is different from said first selected lowering pressure ； a rising pressure control device (310) in fluid communication with both said first rise chamber (35) and with said second rise chamber (35) to control the pressure in said first rise chamber (35) and in said second rise chamber (35), said rise pressure control device (310) being configured to maintain, as a selected rise pressure, any of the continuous pressure ranges
