?¹⁸O And ?D Isotopic Characteristics And Water Sources Of Summer Corn And Winter Wheat In Different Growth Stages

The differences in soil water uptake by different crops limit the understanding of crop growth adaptation and eco-hydrological processes,and it puts forward higher requirements for farmland management.Quantitative study of characteristics of farmland water use and law of water conversion is significant and practical value for the understanding of agricultural water saving irrigation and ecosystem hydrological process.In this paper,the summer corn and winter wheat in Yucheng city of Shandong province were studied.The 8D and ?18O of stem water?precipitation and soil water were measured by hydrogen and oxygen stable isotope technique.On the basis of the direct comparison method and the multi-linear mixed model,the use of different depth of soil moisture and the transform rule of precipitation-soil water-crop water were quantitatively analyzed.The main conclusions are as follows(1)?D??18O and soil water content of different water sources in summer corn and winter wheat were analyzed.It was found that the soil water source during growth period of summer corn was mainly from precipitation.The growth period of winter wheat had less water supply to the soil and precipitation had little effect on ?D and ?18O of soil water.The ?D and ?18O of soil water were enriched from the deep to the surface.(2)Summer corn mainly used 0-15 cm soil water during the seeding stage(73.9%).During the jointing stage,it mainly imbibed water from the 30-55 cm soil layer,and the precipitation was also significantly used during this period.Heading stage used deep soil(30-100 cm).During the filling stage,the amount of soil water absorbed from each layer was similar(15-100 cm,72.0%),and soil water content in each layer was relatively stable.During the mature stage,the summer corn mainly absorbed water from the 30-100 cm soil layer(70.0%).(3)Winter wheat mainly used 0-10 cm soil water during the seeding stage(94.7%).During the wintering stage,it mainly used 0-20 cm soil water(90.8%).It absorbed layers of soil water and concentrated in the 0-60 cm during the jointing stage.The soil moisture at 0-10 cm and 30-80 cm was mainly absorbed during the filling stage,and the contribution rate of the soil at each stage was similar.This paper analyzed the water use strategy of summer corn and winter wheat in Yucheng city,and the results will help to understand the ecological and hydrological processes of farmland system and provide theoretical guidance for the management of water saving irrigation in northern of China.