Font Size: a A A

Spatial Distribution Characteristics And Influencing Factors Of Soil Organic Carbon And Total Nitrogen In Gannan Pastoral Area

Posted on:2020-10-30Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y ZhangFull Text:PDF
GTID:2370330596487075Subject:Geography
Abstract/Summary:PDF Full Text Request
As an indicator to evaluate soil quality and health status of grassland,soil organic carbon and total nitrogen have a direct impact on soil fertility and grassland productivity.To reveal the spatial distribution characteristics and influencing factors of the organic carbon and total nitrogen of the grassland soil in Gannan pastoral area,based on the measured data on the ground,this paper study the organic carbon and total nitrogen content in the change of horizontal and vertical distribution by adopting the combination of classical statistics and statistical methods.This paper had used methods such as common correlation analysis,geographic detector to explore different influence factors on the impact of the spatial distribution of organic carbon and total nitrogen from terrain factor,soil physical and chemical properties,vegetation conditions and climate factors.The research results are as follows:?1?The phenomenon of surface accumulation of the organic carbon and total nitrogen in grassland soil is common.The contents of the organic carbon and total nitrogen in soil at 0-10cm depth were between 8.71-112.10 g·kg-1 and 0.73-8.46g·kg-1,and the average contents were 48.41 g·kg-1and 4.04 g·kg-1,respectively.The contents of the organic carbon and total nitrogen in soil at 10-20cm depth were between 5.28-59.23g·kg-1 and 0.55-9.62g·kg-1,and the average contents were32.55g·kg-1 and 3.02g·kg-1,respectively.The contents of the organic carbon and total nitrogen in soil at a depth of 20-30cm were between 4.75-54.06g·kg-1 and0.41-6.84g·kg-1,with an average content of 25.07 g·kg-1 and 2.39g·kg-1,respectively.The contents of the organic carbon and total nitrogen in soil at a depth of 30-40cm were between 1.98-61.36 g·kg-1 and 0.19-5.76 g·kg-1,with an average content of21.77 g·kg-1 and 2.06 g·kg-1,respectively.The content of the organic carbon and total nitrogen in grassland soil decreased with the increase of soil depth.There were significant differences in the organic carbon and total nitrogen contents between Hezuo city and Xiahe county,Luqu county and Maqu county.?2?The spatial distribution characteristics of the organic carbon and total nitrogen are as follows:the organic carbon content at the depth of 0-10cm decreases from"southwest to northeast,and from west to east";The high value of organic carbon content(40-50 g·kg-1)at 10-20cm depth was mainly concentrated in the south of Luqu county and the central area of Maqu county.The high value of the organic carbon content(30-40 g·kg-1)at a depth of 20-40cm was mainly concentrated in the south of Luqu county and the junction with Maqu county.The total nitrogen content at the depth of 0-10cm is high in the southwest and low in the northeast,and the high value(>4.0 g·kg-1)is mainly distributed in the southwest of Maqu county and Xiahe county,while the low value(2.0-4.0 g·kg-1)is distributed in Hezuo city,the east of Xiahe county and Luqu county.The total nitrogen content at the depth of 10-20cm was mainly in the range of 2.0-4.0g·kg-1.The high value(4.0-6.0g·kg-1)was distributed in the northwest of Maqu county,and the low value(1.5-2.0g·kg-1)was distributed in Hezuo city.The high value of the total nitrogen(4.0-6.0 g·kg-1)at a depth of 20-30cm was distributed in the southwest of Maqu county,while the low value(1.5-2.0 g·kg-1)was mainly in the north of Hezuo city and Luqu county.The total nitrogen content at a depth of 30-40cm was generally distributed in a pattern of"high in the south and low in the north",and the low values(<1.5g·kg-1 and1.5-2.0g·kg-1)were distributed in Hezuo city,Xiahe county,the northern part of Luqu county and the central part of Maqu county.The content of the organic carbon and total nitrogen in grassland soil in the main pastoral areas of Gannan is all at the first and second level.?3?Relationship between spatial distribution of the organic carbon and total nitrogen in grassland soil and topographic factors:with the increase of altitude,the organic carbon content gradually increased at the depth of 0-30cm,and first decreased and then increased at the depth of 30-40cm.The total nitrogen content first increased and then decreased at the depth of 0-40cm.As the slope increased,the organic carbon content first decreased and then increased at the depth of 0-30cm,and then increased and then decreased at the depth of 30-40cm.The total nitrogen content gradually decreased at 0-20cm depth,and first increased and then decreased at 20-40cm depth.With the change of slope direction?overhanging slope-half overhanging slope-half overhanging slope-half overhanging slope-overhanging slope?,the organic carbon and total nitrogen content increased first and then decreased in each soil depth.Relationship between spatial distribution of the organic carbon and total nitrogen in grassland soil and soil physical and chemical properties:among soil types,the organic carbon and total nitrogen content of peat soil and chernozem soil are higher than other soil types.As the total phosphorus content increased,the organic carbon content gradually increased at the depths of 0-20cm and 30-40cm,and first increased and then decreased at the depths of 20-30cm.The total nitrogen content first decreased and then increased at the depth of 0-10cm,and gradually increased at the depth of10-40cm.With the increase of soil water content,the organic carbon content increases gradually in each soil depth.The total nitrogen content gradually increased at 0-30cm depth,and first increased and then decreased at 30-40cm depth.Relationship between spatial distribution of the soil organic carbon and total nitrogen in grassland and vegetation conditions:with the increase of EVI value,the organic carbon content gradually increased at 0-10cm depth,and first increased and then decreased at10-40cm depth.The total nitrogen content gradually increased at 0-30cm,and first increased at 30-40cm depth,then decreased and then increased.Under different vegetation types,the organic carbon and total nitrogen content in the marshy meadow was the highest at 0-10cm depth,while the other soil depths were lower.Relationship between spatial distribution of the soil organic carbon and total nitrogen in grassland and climatic factors:with the increase of MAT,the organic carbon content first decreased and then increased at the depth of 0-10cm,and then increased at the depth of 10-40cm.The total nitrogen content first decreased and then increased at 0-10cm depth,followed by a linear increase at 10-20cm depth,and then increased and then decreased at 20-40cm depth.With the increase of ACP,the organic carbon content of soil depth increased gradually.The total nitrogen content gradually increased at0-10cm depth,and first decreased and then increased at 10-40cm depth.?4?Pearson correlation analysis showed that there were significant relationships between the organic carbon and total nitrogen content at 0-40cm depth and total phosphorus content and soil moisture content,indicating that soil moisture content,total phosphorus content and soil type are key factors affecting the spatial distribution of the soil organic carbon and total nitrogen content.According to the explanatory power of various influencing factors on the organic carbon,soil moisture,total phosphorus,soil type and altitude are the main factors affecting the organic carbon at0-20cm depth,while soil moisture,soil type,total phosphorus and MAT are the main factors affecting the organic carbon at 20-40cm depth.According to the explanatory power of various influencing factors on the total nitrogen,soil moisture content and annual average temperature are the main factors affecting the total nitrogen at 0-10cm and 30-40cm depth,total phosphorus is the main factor affecting the total nitrogen at0-30cm depth,and altitude is the main factor affecting the total nitrogen at 0-20cm depth.It can be seen from the interaction of various factors that the interaction between two influencing factors is greater than the influence of a single influencing factor on the spatial distribution of the organic carbon and total nitrogen content,and most of them are nonlinear enhancement.
Keywords/Search Tags:the organic carbon and total nitrogen content, spatial distribution, influencing factors, geostatistics, geographical detector
PDF Full Text Request
Related items