Effects of rainfall characteristics and covering methods on soil moisture of winter wheat

In order to study the effects of different rainfall characteristics and covering methods on soil moisture of winter wheat, rainfall simulation with rainfall intensity of 40 and 60 mm/h was conducted by using the artificial rainfall simulator. Influences of different covering methods on soil moisture distribution and rainfall storage in soil layer of 0-60 cm under simulated rainfall situations were investigated with setting plastic mulching (PM) , straw mulching with four quantities of 1 500, 4 500, 7 500, and 10 500 kg/hm2 (SM15、SM45、SM75 and SM105 ) and no mulching (CK) in winter wheat field. Results indicated that before rainfall simulating, soil water content in all treatments of mulching was greater than that in CK, of which there was significantly difference in 0-20 cm soil layer (P<0.05) and a little difference beneath 20 cm soil layer, except for SM105, other treatments showed no significant difference compared with CK (P<0.05). Rainfall infiltration depth and volume with 60 mm/h of rainfall intensity was significantly greater than that with 40 mm/h under the same covering treatment and rainfall duration. Soil moisture in plough layer increased in different degrees in all treatments with the same rainfall intensity, which the greater the amount of straw mulch was, the more obvious the increase, but the effect of PM treatment was the worst. At two rainfall intensity conditions, the rainfall storage amount in 0-60 cm soil layer of each treatment had consistent order as SM105>SM75>SM45> SM15>CK>PM, of which SM105 and SM75 were significantly higher than that of CK (P<0.05) and the value of PM was significantly lower than that of CK (P<0.05). As effect of rainfall interception by plant canopy, the rainfall accumulation before the jointing stage was greater than that after the jointing stage under the same rainfall intensity and covering conditions. Compared to the rainfall intensity of 60 mm/h, there was a big difference for the rainfall accumulation amount of each treatment with 40 mm/h rainfall intensity before and after the jointing stage.