The buried boggy soil which is known as "dark earth" popularly are turned up and used as soil mulch in some saline soil region.It has been proved favorable to the improvement of saline soil.The results of laboratory study of its effect on the soil water movement are as follows:1.The dark-earth mulch depresses the upward movement of the capillary water in soil.Its favorable effect on the improvement of saline soil may be attributed to the good structure and more of larger non-capillary pore space of dark-earth.The dark-earth of larger pore apace and the underlying soil of fine pare space constitute a characteristic stratified systems of pore space iu soil,which induces the lower conductivity of soil water and reduces the rate of upward movement of ground-water.Maintenance of the effective dark-earth mulch,therefore,is a favorable measurement for the improvement of saline soil.2.The effectiveness of dark-earth mulch decreased with the rising of ground-water table.Lowerine the around-water table mieht promote the effect of dark-earth on improvement of saline soil.3.In order to maintain the favorable effect of the dark-earth mulch,a thick effestive dark-earth mulch deeper than the ploughing depth is necessary.