Soil infiltration characteristics of winter wheat field during freezing in Hetao Irrigation District

Abstract: In order to reveal infiltration characteristics of the field during freezing based on a winter wheat soil infiltration experiment of the three testing points in the Hetao Irrigation District and by comparing it with the infiltration characteristics of non freezing soil, the infiltration process and characteristics of the field during freezing were discussed. The results showed that the frozen layer thickness was significantly lower than those without mulching under a tectorial membrane and straw mulch in the same freezing period, and that a tectorial membrane plays a significant role in keeping the soil temperature of that frozen layer thickness six centimeters lower than non mulch，however the impact of retaining the soil temperature is poor under straw mulch. Mulching and straw mulch can decrease the speed of frozen soil water, but the impact of the soil frozen layer thickness is slow under a tectorial membrane and straw mulch with the advance of the freezing, and the impact was best in the early freezing of the tectorial membrane and straw mulch. The non-frozen soil water content of it was gradually reduced with the advance of the freezing under total soil water content in little change from non-freezing stage to stable freezing stage, and the speed process was from slower to quicker and to slower of non frozen soil water content translate into the frozen soil water content. Straw mulch can slow down the conversion of non-frozen soil water and the impact is better in the initial freezing stage and mid freezing stage, but the impact is significantly reduced in the stable freezing stage, and the impact of tectorial membrane mulching is better than straw mulch in all freezing stages. The infiltration rate of freezing soil water is far less than the non-freezing soil and the soil infiltration rate is reduced with the frozen layer increased; with the freeze stability of soil water the stable infiltration rate decreased eighty-five percent or more and it was gradually reduced with the advance of the freezing period; the effect of the tectorial membrane was significant and better mitigation soil freezing, and the infiltration rate was reduced respectively about nine point eleven percent and thirteen point fifty percent compared with no coverage in early and mid- freezing soil, and the straw mulch is worse than tectorial membrane with reduced infiltration rates that were four point ten percent and seven percent compared with no coverage in the early and mid- freezing soil. The cumulative infiltration quantity of the frozen soil was much less than that of the non-frozen soil, and the cumulative infiltration quantity was increased under the tectorial membrane and straw mulch in the initial freezing stage and the mid-freezing stage, but the effect for the cumulative infiltration quantity was very poor for the tectorial membrane and straw mulch in the stable freezing stage. The infiltration process of the field during freezing can be expressed by a Kostiakov model and a Kostiakov-Lewis model in that no significant differences used the data to simulate the infiltration process of freezing soil. However, the Philip infiltration model was not suitable to simulate it. The result was of definite significance for the designed an irrigation schedule of winter wheat in autumn irrigation in the Hetao Irrigation District and to establish a foundation for the study of transport coupled with water, heat, and salt during the freezing period.