Abstract:

The response of shallow soil moisture increment to precipitation was analyzed to provide a meteorological basis for promoting quinoa planting in arid areas. The data of two automatic soil moisture monitoring stations in eastern Qaidam Basin from April to October in 2018-2021 were used for the study, including precipitation, shallow soil water content before precipitation, average temperature during precipitation and precipitation duration. Statistical analysis was performed by Excel and SPSS. The results are as follows. (1) In quinoa growing season, compared with those in Delingha, the small precipitation events were 4% less and the large precipitation events were 6% more in Ulan; the response of soil moisture increment to precipitation in both places showed a lag, and depending on soil depth and precipitation intensity, the single lag time ranged from 1 h to 63 h. (2) Under the same magnitude of precipitation, the soil moisture increment gradually decreased with the increase of soil depth; with the increase of precipitation level, the water content of the same depth layer increased gradually. (3) When the cumulative precipitation was less than 5 mm, the moisture in 0-10 cm soil layer changed, but the moisture in 10-40 cm soil layer did not change; when the precipitation was 5-10 mm, the soil water content of 0-40 cm increased by different amounts according to the surface water content before precipitation; when the precipitation was more than 10 mm, the average soil water content in each layer of 0-40 cm increased significantly. (4) The response of water content in 0-10 cm soil layer to precipitation was insignificantly and negatively correlated with temperature during precipitation, and it was positively correlated with the water content before precipitation, which was significant in Wulan and not obvious in Delingha. The correlation between the response and the precipitation duration was significant (P<0.01). The results could be used as reference for studying water demand of quinoa in each growing period, quinoa water absorption after rain and irrigation.

Key words: soil moisture, increment, precipitation events, eastern Qaidam Basin