| The revelation of organic carbon distribution in different soil aggregates of Wutai Mountain vertical zone can provide theoretical basis for rational utilization of soil in this area.The soil samples in vertical zone of Wutai Mountain were taken in this study,and the subalpine meadow soil,mountain meadow soil,brown soil,leached cinnamon soil,and calcareous cinnamon soil were collected from high altitude to low altitude.Also,the>2 mm,2～0.25 mm,0.25～0.053 mm and<0.053 mm levels of water-stable aggregates in different type soils were harvested through wet-sieving method and physical fractionation technique,and the TOC,POC,MOC,Ca-SOC and Fe(Al)-SOC of all level aggregates and soils were further analyzed.The main conclusions are as follows:(1)The subalpine meadow soil,mountain meadow soil,and brown soil all mainly composed by>2 mm aggregates,and it can reach 45.13%of all water-stable aggregates.However,cinnamon soil and calcareous cinnamon soil were mainly composed by 2～0.25 mm and 0.25～0.053 mm aggregates respectively,reached 33.79%and 39.95%.With the reduce of altitude,soil organic carbon content decreased.Besides,the organic carbon content of>2 mm and 2～0.25 mm aggregates in different type soils had a great significant positive correlation with the corresponding soil organic carbon content and the correlation coefficients were r>2 mm=0.986,r2～0.25mm=0.966(P<0.01).(2)The content of TN in soils decreased with the decrease of altitude,while the content of TP decreased first and then increased with the increase of altitude.The contents of TN and TP in mountain meadow soil and mountain brown soil were mainly concentrated in macro-aggregates,while E is mainly concentrated in micro-aggregates.With the decrease of aggregates’ particle size,the TK content of subalpine meadow soil,mountain meadow soil and mountain brown soil showed the distribution of "V"shape,while cinnamon soil and calcareous cinnamon soil showed the distribution of reversed "V" shape.(3)With the decrease of soil aggregates,the POC contents of sub alpine meadow soil decreased,the POC contents of leached cinnamon soil and calcareous cinnamon soil increased.The MOC content of subalpine meadow soil,mountain meadow soil and brown soil were largest in>2 mm aggregates,and leached cinnamon soil,calcareous cinnamon soil were respectively highest in 2～0.25 mm and 0.25～0.053 mm aggregates.The soil MOC content was significantly greater than POC,and the two showed a positive correlation in soils and macro-aggregates(P<0.05).In addition,the content of POC and MOC in soils also showed a positive correlation with the content of soil organic carbon(P<0.05).(4)With the decrease in particle size of aggregates,the Ca-SOC and Fe(Al)-SOC contents of mountain meadow soil decreased first and then increased,while cinnamon soil increased first and then decreased,and also mountain brown soil decreased gradually but calcareous cinnamon soil increased gradually.The correlation analysis showed that the soils and>2 mm aggregates had a significant positive correlation between Fe(Al)-SOC and TOC,the correlation coefficient were r 土壤=0.898(P<0.05)and r>2 mm=0.978(P<0.01).The content of Fe(Al)-SOC in soils and all level aggregates was significantly higher than that of Ca-SOC,and the contents of Ca-SOC and Fe(Al)-SOC in 2～0.25 mm and 0.25～0.053 mm aggregates were significant positive correlation.Therefore,the soil aggregates form was turned from macro-aggregates in higher altitude areas to micro-aggregates in lower altitude areas,and the carbon capture ability of subalpine meadow soil,mountain meadow soil and brown soil was stronger than leached cinnamon soil and calcareous cinnamon soil.The content of TN in soils decreased with the decrease of altitude,and except calcareous cinnamon soil,the TN contents of other soil macro-aggregates(>0.25 mm)were significantly higher than that of micro-aggregates(<0.25 mm).With the decrease of aggregates’ particle size,the contribution rate of aggregates to the content of TP was decreased,and the Fe-Al-bonded organic mineral complex had stronger ability to maintain phosphorus than Ca-bonded.The bonding ability of Fe-Al bond and the stability of Fe-Al complex were higher than Ca-SOC,and the content and distribution ratio of Fe(Al)-SOC in soil and all level aggregates were significantly higher than Ca-SOC. |
PDF Full Text Request