关键词: 土壤水分, 土地利用方式, 典型黑土区, 季节变化, 剖面特征

Abstract:

Soil moisture is an important impact factor of agricultural production and regional ecosystem. The No. 2 small watershed in Heshan farm of Heilongjiang Province was selected as the study area, the characteristics of the dynamic of soil moisture and soil water profile in different land use types were analyzed in this article. The results showed that: the soil moisture of embankment was the maximal, and the woodland’s was the least. The variation trends of soil moisture content of different land use types were as same as the variation trend of precipitation in the observation period, and they showed a reduced trend, but there were some differences between the soil moisture variation curves of different land use types, the soil moisture cures could be divided into three types: two peaks and three troughs type (wheat field, soybean field, woodland and field road), two peaks and two troughs type (embankment), two peaks and one trough type (grassland). The soil moisture variation in the observation period was divided into relatively stable period, consumption period, and supply period. The influence of land use type on the water content of soil profile increased with soil depth, and the soil moisture of different land use types showed different variation trends with soil depth. Among them, because of the presence of plow pan, the soil moisture of wheat field and soybean field increased first and then decreased; the soil moisture of woodland decreased gradually with the soil depth; the soil moisture of grassland and field road for the difference soil property reason presented the trend of increased first and then decreased, but the max soil moistures of these two land types appeared in different depth; because of the soil property did not change with soil depth, the soil moisture of embankment increased gradually with the soil depth. In addition, there is also a seasonal diversity in the water content change of soil profile in every land use type. The water content variation of soil profile in wheat field appeared an obvious seasonal diversity, but with the increase of soil depth the diversity decreased; the seasonal change of soil moisture in soybean mainly in the depth of 0-70 cm, and the seasonal change was not obvious under the depth of 70 cm; the seasonal diversity of soil moisture change in each section of soil profile in woodland is the largest; the top layer and the layer in the depth of 70-80 cm which was composed by peat were the layers that seasonal diversity of soil moisture in grassland mainly happened, and the diversities of other layers were small; because of there were not any plants on the field road, and the soil moisture variation subjected only to the influences of rainfall and evaporation, the seasonal diversity of soil moisture in field road mainly appeared in the top layer of soil, but the diversity in deeper layer were not obvious; the seasonal diversity of soil moisture in embankment was as same as field road, but the reasons that leaded this phenomenon were that the soil property were all the same from top to bottom, and the soil moisture of top layer was effected by the plants, precipitation and evaporation. Besides the land use types, slope position and direction, soil texture, topography are all the important influence factors for the dynamic changes of soil moisture, further studies are needed to determine the interaction of these factors above and the main control factors.

Key words: soil moisture, land use type, typical black soil region, seasonal variation, profile properties