In order to explore water hold capacity of water storage clay and improve soil water movement characteristics of the Loess Plateau

the water retention test of water storage clay and the indoor infiltration and evaporation test of soil column with water storage clay layer were carried out. Three particle size levels (20~30

5 and 2 mm) were set for water storage clay. The thickness of water storage clay layer over the soil column was 5 cm

and the treatment without water storage clay was used as control (CK). The results showed that when the room temperature was 15 ℃

three particle sizes of water storage clay could reach saturation within 40s

and the water absorption rate was between 30%~90%. Meanwhile

the water release rate was relatively slow

so it indicated that the water retention of water storage clay was better. In terms of the infiltration of the soil column

the migration distance of wetting front was significantly promoted by water storage clay with different particle sizes

and the cumulative infiltration amount increased by 40%~60% compared with CK

and it increased with the increasing of the particle size. In terms of soil column evaporation

after continuous evaporation of seven days

soil evaporation was inhibited in varying degrees by water storage clay with different particle sizes. Moreover

the inhibition effect was the most obvious when the particle size was 5 mm

its accumulated evaporation was 67.23% lower than that of CK. The overlying water storage clay layer could reduce the loss of soil water. The soil moisture content in the 10—25 cm soil layer of the soil column covered by water storage clay with different particle sizes increased by 4~5 times compared with CK. With comprehensive consideration of soil infiltration and evaporation

the effect was the best when the particle size of water storage clay was 5 mm. This study could provide theoretical basis for constructing methods to improve the infiltration and storage capacity of slope on the Loess Plateau.