Study On Soil Types And Organic Carbon Pools In Cultivated Land In Chin

China is a large agricultural country,with a national cultivated area of about 120 million hectares,accounting for about 7%of the global cultivated area.However,China’s population accounts for 20%of the world’s total population,with a per capita cultivated area of less than0.1 ha,only 40%of the world average.China is currently facing serious challenges,and climate change caused by rapidly increasing greenhouse gas emissions will further affect the normal life of mankind.Soil carbon pool is an important component of terrestrial ecosystems and plays an important role in the global carbon cycle.Its small changes may have a significant impact on the atmospheric CO₂ concentration,thereby affecting global climate change.The SOC density of cultivated land in China is generally lower than the average level in developed countries such as Europe and the United States and the world,indicating that China’s cultivated land has greater carbon sequestration potential under optimized management measures.This study comprehensively utilized land use type data,soil to bedrock depth data,soil texture data,soil type data,and soil organic carbon content data to analyze the differences in physical and chemical properties of different soil types,and explored the changes in the soil organic carbon pool of surface arable land in China from 2010 to 2020,as well as the changes in organic carbon content under various soil types,providing a map of the basic status of arable land and soil types in China,Evaluate its carbon sequestration potential and provide sustainable carbon sequestration management measures for agricultural production.The main conclusions are as follows:（1）The main soil types of cultivated land in the eastern agricultural region of China are artificial soil and alluvial soil,while the main soil types of cultivated land in the northern agricultural region are embryonic soil and chestnut soil,while the main soil types of cultivated land in the southern agricultural region are low active strong acid soil and artificial soil.The depth of cultivated soil to bedrock is the largest in the Middle and Lower Yangtze Valley Plain and the Huang Huai Hai Plain in China.The soil types with the highest depth to bedrock in the two agricultural regions are artificial soil,reaching 156 m and 155 m respectively.The areas with lower depth from soil to bedrock are mainly concentrated in South China and Sichuan Basin agricultural regions in southern China.The texture of the main cultivated land soil types located in the Middle and Lower Yangtze Valley Plain and the Huang Huai Hai Plain in China is inclined to silt and loam,while the corresponding texture of the cultivated land soil types located in the southern agricultural region is mainly inclined to clay and loam.（2）From 2010 to 2020,with the impact of land use changes and human activities,the soil organic carbon pool of China’s topsoil has changed to a large extent.The most significant reduction of soil organic carbon in the Middle and Lower Yangtze Valley Plain was 216.8 Tg,followed by a reduction of 178.6 Tg in the agricultural area of the Sichuan Basin.The main reason is that the anthropogenic soil,low active strong acid soil and rudimentary soil in the Middle and Lower Yangtze Valley Plain The decrease in SOC in anthropogenic soils resulted in an increase of 154.7 Tg in organic carbon storage in the Northeast Plain region,mainly due to the carbon fixation of highly active leached soils in this agricultural region.In terms of soil organic carbon content,the increased soil types were mainly the highly active eluvial soil and glei soil in the Northeast Plain region,and the highly active eluvial soil in the Loess Plateau region increased by 3.7,2.4,and 1.66 kg C/m²,respectively.The decreased soil types were mainly the anthropogenic soil in the Qinghai-Tibet Plateau region,and the anthropogenic soil in the northern arid and semi-arid region,decreased by 4.63 and 3.17 kg C/m²,respectively.（3）Based on the data extraction of land use types in 2010 and 2020,cultivated land（fixed cultivated land）without land use change in the past 10 years was obtained,and the soil organic carbon pool of these cultivated land was studied.The SOC of surface farmland in the agricultural area of Sichuan Basin decreased by 137.4 Tg in total,followed by 109.4 Tg in the northern arid and semi-arid areas,91.9 Tg in the Middle and Lower Yangtze Valley Plain,and99.7 Tg in the Northeast Plain,where the organic carbon storage increased significantly.Compared with other soil types,the soil organic carbon content of the anthropogenic soil in the Qinghai Tibet Plateau,the northern arid and semi-arid areas,and the rudimentary soil in the agricultural area of the Sichuan Basin has a significant reduction trend,with 4.63 kg C/m²,3kg C/m²,and 2.4 kg C/m²,respectively.The more obvious increase in soil types is mainly the highly active eluviate soil in the Middle and Lower Yangtze Valley Plain,and the alluvial soil in the northern arid and semi-arid areas,with 3.6 kg C/m² and 1.2 kg C/m²,respectively.In summary,according to the soil types under different geographical distributions in China,it is necessary to optimize the management of cultivated land with severe losses in organic carbon storage,focus on protecting cultivated land with carbon sequestration potential,while improving the soil carbon pool,maintain the sustainable development of cultivated land,and serve the high-quality development of agriculture in China.