International audienceDrought is a major disaster which Beijing agricultural systems faced with, build drought warning mechanism we need in-depth analysis the causes and mechanism of the drought to provide a basis for scientific disaster reduction and prevention. VAM vulnerability assessment method, selected 15 factors represent drought exposure, sensitivity and adaptive capacity, based on improved analytic hierarchy process to determine the weight of each factors, use K-means clustering algorithm to generate the drought vulnerability index system of research district. Draw vulnerability zoning map based on ArcGIS
Drought is a major disaster that Beijing agricultural systems faced with. The risk of drought disasters is a result of drought disaster together with vulnerability, the result of drought disaster only appeared in post-disaster, before the disaster occurred, we need to make some research on drought vulnerability that Beijing agricultural systems faced with, we choose VAM (vulnerability assessment method) that consist of three drought elements: exposure, sensitivity and adaptive capacity, based on two kinds of analytic hierarchy process method to determine the weight of each factors. try to verify the results of agricultural drought indicator system through the spatial distribution map of soil moisture, as well as explore the key factors that influence Beijing agricultural drought vulnerability.
Pulse and continuous irrigation can affect water distribution in the soil, thereby affecting the growth and distribution of root systems. Different base and topdressing fertilizers can affect nitrogen transport in the soil and root distribution, thus affecting root water and nitrogen uptake. This study used pot experiments to set up four different nitrogen levels, including two different irrigation methods, to research the effects of soil moisture, nitrogen transport, nitrogen accumulation and root systems under the conditions of continuous and pulse irrigation, as well as different nitrogen applications. Result showed that continuous irrigation can increase the moisture content around the drip emitter position and reduce the soil moisture content in the horizontal spreading compared with pulse irrigation, especially reducing the horizontal spreading in the deep soil layers. One treatment in this study did not apply base fertilizer, and then supply topdressing fertilizer at a ratio of 2:4:4 in the seedling stage, jointing stage and tasseling stage, respectively. This treatment is beneficial for improving nitrogen utilization efficiency. Furthermore, this treatment can increase the root length density and root surface area in the deep soil layers, especially in the 20-35 cm soil depth, and to some extent increase the deep growth of the root system.
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