Analysis of influential factors for maize root water uptake based on Hydrus-1D model

In order to investigate the mechanism of the influence of soil texture, growing state and weather conditions on the root water uptake under various soil moisture conditions, the relationship between root water uptake rate and soil moisture content was used to evaluate soil moisture availability and a Hydrus-1D model was used to analyzed the dynamic changes of root water uptake with various water content with maize growing with different leaf area index, root depth and root density distribution in three soil textural types (loam clay, clay loam and sandy loam) under three weather conditions. Results showed that the root water uptake rate in various conditions remained constant until soil moisture content decreased below a critical value and then declined in a different way under different conditions with further soil moisture depletion. The critical values were different for different soil texture, plant leaf area index and evaporative demand, among which root depth and root density distribution also had significant influence on the relationship between root water uptake and soil moisture content. However, the dynamic change of root water uptake for maize to plant growing state and weather condition was different in the three soils. In general, the critical soil moisture content declined with soil texture in the order: loam clay > clay loam > sandy loam, increased as evaporative demand increasing and decreased as root depth and root density distributed in the deep depth increasing. The effects of various factors on maize root water uptake decreased in the order: soil texture > root density distribution > root depth > evaporative demand > leaf area index.