Changes of Water Quality and Bacterial Number in Overlying Water during the Wheat-Straw Returning to Field

By taking advantage of the model of wheat-straw returning to field, we investigated the survey on the transitional trend of the temperature, pH, DO, COD and the bacterial number of the overlying temperature when wheat-straw returned to field. The result indicated that on the 22nd day of the test, the pH (7.60) and DO value (4.12 mg/L) of the wheat-straw returning stimulation area were obviously lower than the pH(7.85) and DO value (6.98 mg/L) of the control area. However, the COD value (35.0 mg/L) was clearly higher than that of the control area (26.0 mg/L). The result showed that the organic content among the overlying water in the straw returning stimulation area was improved and meanwhile the capacity of the self-purification of water is lower. At the same time, there was no significant difference of the total number of bacteria between the overlying water and the control area (p=0.656218). However, the proportion of cellulose bacteria was the 75 times of that in the control area, with the absolute growth advantages.