Abstract:
Soil water is the limiting factor for agricultural production in seasonal arid area, so the study of moisture characteristics of Purple Soil can help solve the eco-hydrological drought problem of cultivated slope land. Taking the Purple Soil of cultivated slope land in a seasonal arid area as the research object, the PR2/6 soil profile moisture analyzer was used to monitor soil moisture contents within 0-100 cm depths at 5°, 10°, 15°, 20°, 25°, 30° slopes in a rainy season. The characteristics of soil moisture were investigated. The change of soil moisture content with time was divided into four stages: soil moisture recovery period (from the beginning of June to the end of June), soil moisture rapid replenishment period (from the beginning of July to the middle of August), soil moisture consumption period (from the middle of August to the end of August) and soil moisture raise period (from the beginning of September to the end of September). Soil moisture content was increased with the increase of soil depths. The soil moisture content had a significant difference and correlation among different depths. The soil moisture content in six sites all appeared the maximum at 100 cm depth with the range of 19.67%-33.82%, while the minimum mostly occurred at 20 cm depth, ranging from 3.07% to 11.71%. The coefficient of variation (C.V.) of soil moisture content decreased with the increase of soil depths. The C.V. was the largest at 10 cm depth, ranging from 8.67% to 56.28%, but was the lowest at 100 cm depth, ranging from 0.68% to 14.76%. The soil moisture content generally decreases with the increase of slope. The soil moisture contents within 0-60 cm depths were higher at the 10° slope than those at the other slopes, ranging from 12.20% to 20.40%; the soil moisture contents within 0-100 cm depth were relatively low at 25° slope, ranging from 4.28% to 19.22%. Both rainfall and slope have significant influence on soil moisture content. With the increase of soil depth, the influence of both rainfall and slope on soil moisture content decreased. These results were of great significance for the efficient use of water resources and the improvement of agricultural productivity of cultivated slope land in seasonal arid areas.