Abstract: Based on the 1981-2006 phenological and meteorological data of Hebei Province, the spatiotemporal characteristics of soil surface freezing and thawing in the province in response to climate change were analyzed. An obvious regional difference was observed in the phenological phases of soil surface freezing and thawing. In the southeast coastal plain area of the province, the beginning phase of freezing was later, thawing phase was earlier, and frozen phase was shorter; while in the north and northwest mountain areas, they were in contrary. Compared with the past years average phenological dates, the beginning phase of freezing in the province before the early 1990s was earlier, thawing phase was later, and frozen phase was longer, but after the late 1990s, the beginning phase of freezing in most areas of Hebei Province delayed, beginning phase of thawing advanced, and frozen phase shortened. Air temperature had significant effects on the phenological phases of soil surface freezing and thawing in the areas with lower terrain. In case that the air temperature in autumn was increased by 1 ℃, the beginning phase of freezing would be delayed 3.8 days. If the temperature from February to March increased 1 ℃, the beginning phase of thawing would be 5.3 days earlier; if the air temperature from October to next March increased 1 ℃, the frozen phase would be shortened by 12.6 days.

Key words: Rice straw, Quick decomposing, Chemical biological combined decomposing technique, FTIR spectroscopy