Changes Of Soil Organic Matter And Nutrients In Three Soils Of Shandong Province Over25Years

Soil organic matter (SOM), nitrogen (N), phosphorus (P) and potassium (K) could indicate soil fertility condition and play a crucial role in plant growth. At present, ecological environment problems caused by unreasonable fertilization and management were increasing seriously. Greenhouse gases from which SOM decomposed increasingly affected the global climate change. Soil nutrients loss in quantity leaded to crop reduction of output, water eutrophication and environmental pollution. Formulating reasonable fertilization and management scheme, improving utilization rate of fertilizers, reducing nutrients loss and balancing soil nutrients were the topic of soil science now and in the future. In this paper, typical soils in Shandong province as objects were researched to analyze comprehensively the change rule of soil organic matter (SOM) and nutrients during last25years in order to provide scientific supports for formulating reasonable fertilization scheme and scientific management measures, improving soil structure and nutrients condition, protecting ecological environment. Main results were summarized as follows:1. Over nearly25years, the average content of SOM in the whole profile (0-80cm) in three soils (brown soil, cinnamon soil and fluvo-aquic soil) of Shandong province increased by15.00%～50.00%, and SOM contents in top layer (0-20cm) were significantly higher than the below (20cm-) soil types about20percentage points.2. Compared with25years ago, reduction of SOM contents in three soils between the top soil (0～20cm) and the subsurface (20～40cm) were20.00%～70.00%. SOM contents in three soils increased significantly over25years, but SOM contents of cinnamon soil was higher than of brown soil and fluvo-aquic soil overall.3. Over25years, the TN, AP and AK contents of the three soils in top soil layer increased respectively from0.60g kg-1、6.89mg kg-1、102.75mg kg-1of1986by0.50-0.70times,4.50～9.74times and0.49～0.83times. The average increase of TN, AP and AK contents in three soils of20-80cm were0.25times,5.54times,0.33times.4. Compared with1986year, reduction of N, P, K nutrients in three soils between the top soil (0-20cm) and the subsurface (20-40cm) were higher, while the highest TN content among the three soils was fluvo-aquic soil, the highest AP content was cinnamon soil and the highest AK content was brown soil.5. Compared with1986year, the contents of SOM and N, P, K nutrients in three soils all increased to some extent. The lever of the content of SOM and TN were still lower and their classification was6～4; while AP and AK increased significantly and their classification was4-2.