Study On Soil Status Of Heixiazi Island In The Original Ecological Area Of Sanjiang Plain

The Sanjiang plain in northeast China has experienced a century of large-scale agricultural development since the 1950s,and now it has become an important commodity grain base in China.Agricultural development has also caused the thinning of black soil layer,hardening and other problems.In order to solve the soil degradation of farmland soil background values of the Sanjiang plain questions,this research to in the original state of Heixiazi island dark brown soil,meadow soil and swamp soil physical and chemical properties,soil microorganism and enzyme activity characteristics,the soil quality was studied,and it compared and analyzed the soil related indexes of the lons-term tanning state in Sanjiang plain,and the results showed that:1)The soil organic carbon content and other nutrient indexes in Heixiazi island decreased with the order of dark brown soil,meadow soil and swamp soil,and also decreased with the depth of soil layer.Soil bulk density decreases with the order ot soil type meadow soil,dark brown soil and swamp soil.2)The number of soil microbes decreased with the order of soil types of swamp soil,dark brown soil and meadow soil.Soil actinomycetes accounted for the highest proportion in the total microbial population.There are different seasonal changes of soil enzyle activities.The activity of soil catalase is lower in summer than in autumn,the activity of soil invertase is higher in summer than in autumn,and there is no obvious seasonal change ot soil urease.3)The soil quality index of Heixiazi island decreased with the order of dark brown soil,meadow soil and swamp soil.4)The results of comparison of soil nutrient indices between Heixiazi Island and cultivated land in Sanjians Plain are as follovvs:The content of organic carbon and total nitrogen in the dark brown soil of Heixiazi island was three times higher than that in cultivated soil.The content of organic carbon and total nitrogen in dark brown soil was 1.6 times higher than that in the soil returned to forest land,and the content of total phosphorus was slightly lower than that in the soil returned to f'orest land.The content of organic carbon,total nitrogen and total potassium in Heixiazi island meadow soil is 0.4?1.4 times higher than that in the soil of returning to grassland,and the content of total phosphorus is less than half of that in the soil of returning to grassland.