Dynamic variation and impact factors of red soil moisture in low mountain-hilly region

The red soil, distributed in many provinces in China, has great potential for agricultural development. But seasonal drought and low available soil moisture restrict agricultural production in the red soil region. In the study, soil moisture and physic-chemical properties of red soil were determined to analyze the soil moisture dynamic variation in different periods and to find out the profit and loss of soil moisture and their impact factors. The results showed that the variation of red soil moisture in one year could be divided into four phases: filling phase (from March to June), deficit phase (from June to August), recovery phase (from August to October), and stable phase (from October to March). In different experimental plots, meteorological factors had different influences. Effects of evaporation on N plot, NP plot, and NPK plot showed the digressive trend. On contrast, effects of rainfall showed the ascending trend. The plot with no fertilizer, which had no plant growth, could be influenced directly by evaporation or rainfall. It can play a very important role in water resources management, irrigation arrangement and drought evaluation by mastering the trend of the soil moisture dynamic variation in the red soil region.