DYNAMIC CHANGE OF SOIL PROPERTIES IN THE RHIZOSPHERE OF MAIZE AND SOYBEAN

In order to investigate the dynamic change of soil properties in the rhizosphere, root mat boxes were applied to separate rhizosphere soil from root system, and a series of rhizosphere and non rhizosphere soils were sampled at different growth stages of maize and soybean. Wet soil pH, dissolved organic carbon (DOC) and microorganism mass were measured over time by routine analysis methods, while oxidation reductive potentials (Eh) were measured in situ by microelectrodes. The results showed that the properties of the rhizosphere soil varied significantly. During the early stage of growth, DOC concentration in rhizosphere increased rapidly and DOC decreased gradually after 20 days. Change in pH of the rhizosphere followed a similar pattern. During the 100 days of the study, Eh decreased continuously while microorganism mass increased gradually. The patterns of the changes were very similar for maize and soybean while the magnitude of the change in the maize rhizosphere were larger than that in the soybean rhizosphere.