| Farmland soil carbon pool plays an important role in the terrestrial carbon cycle,and changes in soil carbon content are of great significance to the soil carbon pool.This study collected and summarized the data of the second soil survey in Xinjiang in 1980 and the soil series survey data in 2014.Using mathematical statistical methods such as variance analysis,correlation analysis and regression analysis,combined with soil total nitrogen,total phosphorus,p H,altitude and climate and other influencing factors,comparative analysis of the characteristics of carbon content changes in different soil types in the past 30 years has initially revealed the past 30 years The trend of soil carbon content change in northern Xinjiang,and on this basis,the relationship between carbon content and soil total nitrogen,total phosphorus,p H and climate factors are discussed.The main results obtained are as follows:(1)In 2014,the average content of soil organic carbon in northern Xinjiang was 10.68 g/kg,the content of inorganic carbon was 13.87 g/kg,and the total carbon content was 24.55 g/kg.Compared with1980,the average content of soil total carbon showed an increasing trend.An increase of 10.44%(3.55g/kg),of which the inorganic carbon content increased by 2.39 g/kg,accounting for 67.32% of the total carbon content change,and the organic carbon content increased by 1.16 g/kg,accounting for 32.68% of the total carbon content change.The soil carbon content of farmland in northern Xinjiang is dominated by the increase of inorganic carbon content.Among the various soil types,the total carbon content of marsh soil was significantly lost,with a decrease of 25.66%(8.72 g/kg),and the content of meadow soil increased most significantly,with a change of 23.52%(8.00 g/kg).(2)The distribution and change characteristics of soil carbon content in northern Xinjiang in the past30 years are analyzed from the altitude intervals of 0～500,500～1000,1000～1500,and 1500～2000 m: the highest organic carbon content and total carbon content are located in the altitude range of 1500～2000 m.The highest inorganic carbon content is in the range of 500～1000m altitude;From the analysis of the amount of change,compared with 1980,the soil organic carbon increased in the range of 1500～2000 m in2014,with a rising rate of 28.92%,and the inorganic carbon content increased in the range of 500～1000 m with an increase of 12.05%.The total carbon content in the 1500～2000 m altitude range,the increase is significant,with a rate of change of 38.82%,and the 1000～1500 m altitude range has a significant loss,with a rate of change of 12.26%;Altitude is linearly positively correlated with organic carbon content,linearly negatively correlated with inorganic carbon content,and linearly positively correlated with total carbon content.(3)Most soil types are in the 0～100 cm soil layer,and the soil organic carbon content decreases with the depth of the soil layer.The soil inorganic carbon content is mostly in the 0～80 cm soil layer.Deepening shows an increasing trend,and the vertical distribution of total carbon profile is similar to that of organic carbon.From the analysis of the variation,most of the organic carbon of different soil types shows that the variation of the surface layer is greater than the variation of the bottom layer,and the variation of inorganic carbon is smaller than the bottom layer.The deepening of the soil layer shows an upward trend.(4)Soil total nitrogen,total phosphorus and p H affect soil organic carbon,inorganic carbon and total carbon content to varying degrees.In 1980,soil organic carbon and total nitrogen showed a very significant correlation in each layer(P<0.01),and were significantly correlated with total phosphorus at 60～80 cm(P<0.01).In 2014,soil organic carbon was significantly correlated with total nitrogen.There is a significant negative correlation between p H in 20～60 cm and 80～100 cm soil layers(P<0.01),a very significant correlation with soil total nitrogen in 20～40 cm(P<0.01),and total phosphorus in 0～40 cm cm was significantly positively correlated(P<0.05);soil inorganic carbon was significantly correlated with p H at40～60 cm in 1980(P<0.05),and was extremely significantly correlated with total nitrogen at 60～80 cm in2014(P< 0.01),there was a significant correlation with total phosphorus in different soil layers in the two periods;the significant relationship between total soil carbon and p H in 1980 was shown in the 0～60 cm soil layer,and was significantly correlated with total nitrogen and total phosphorus in 40～100 cm(P<0.05).Compared with total phosphorus and p H,the relationship between total soil carbon and total nitrogen in2014 was more significant(P<0.05).(5)The annual average precipitation and the annual average temperature jointly affect the changes in the soil carbon content in northern Xinjiang on the time scale.The correlation coefficient between the soil organic carbon content and the average annual precipitation is greater than the correlation coefficient with the annual average temperature,indicating a significant impact The content of soil organic carbon is the average annual precipitation;the inorganic carbon content of the soil is highly correlated with the average annual precipitation and the average annual temperature,and the relationship between the average annual precipitation and the soil inorganic carbon is significant at 40-100 cm(P<0.05),the average annual temperature is significantly correlated from 0 to 100 cm(P<0.05);and the correlation between total soil carbon content and the average annual precipitation is stronger than the correlation between the average annual temperature.In summary,the increase in the organic carbon content of farmland soil in northern Xinjiang indicates that the quality of farmland soil has been improved,and the increase in the inorganic carbon content of farmland soil indicates that there is a certain risk of secondary salinization in farmland soil,while the total carbon content of farmland soil is lower.Increase has a certain contribution to curbing the greenhouse effect.Soil total nitrogen,total phosphorus,p H,annual average precipitation,annual average temperature,different soil types,soil depths and altitudes all have a certain impact on the distribution and changes of soil carbon content.In the study of the characteristics and changes of soil carbon content in farmland When considering the influencing factors,not only the above factors should be considered,but also the influence of farmland management measures,fertilization amount,straw return amount,irrigation amount,irrigation method and other factors on soil carbon content. |
PDF Full Text Request