A substantial big reclamation project for agricultural production is currently taking place at Isahaya Bay, Nagasaki prefecture located in the southwest of Japan. To improve the soil physical properties, a large amount of gypsum was added to the original heavy clay soil. Also, leaching was conducted for several months using a sprinkler to carry out the salts in the land surface. In this report, some trials to control the salt damages were introduced. First, the soil's physical properties at the newly reclaimed field were introduced. Second, the pot experiments on the soil salinity movement when the surface layer was plowed were conducted. Finally, numerical studies on the soil water movement and salt movement in the fields were stated. So experimental and numerical effects on plowing soil surface were carried out. Results from the experiments were that the accumulation of salts at surface layer was controlled because of the plowing effects that it cut off the capillary in the soil. Furthermore the rainfall and the irrigation into the field worked as action of reaching. It obtained more effects of the control of salts accumulation than dry states. Though the results of the study are applicable for warm and humid climatic conditions with reclaimed land soils, the objective methodology developed has universal applicability.