Abstract A new method is proposed for soil improvement of salt-affected soils in regions where a sufficient amount of rainfall occurs in summer. The subsoil is made coarse by soil sintering, and the capillarity from groundwater is cut off. Thus, the rise to the soil surface of salts which are dissolved in the groundwater is prevented. Moreover, the salts that accumulate in the topsoil are washed out by rainfall (leaching) during the summer season. In this paper, based on the previous experiments of soil sintering, a prototypical soil-sintering plough was developed to make soil coarse. A stationary soil-sintering device was used to determine optimal conditions of thickness of spread soil on the conveyor, and conveyor speed. When this soil thickness was 15 mm and the conveyor speed was 5.7 mm s-1, the maximum thermal efficiency (about 30%) was obtained. When these conditions were applied to a prototypical soil-sintering plough attached behind a tractor, the required plough travel speed was 1.9 mm s−1 (6.84ß10−3 km h−1) for practical use with 3 burners, 90 mm in the operating depth and 300 mm in the operating width.