Simulation On The Future Change Of Soil Organic Carbon Under Different Tillage Managements And Carbon Sequestration Potential In The Northeast Dryland

Soil organic carbon?SOC?fixed problem become a hotspot research as the global CO₂concentration rising in atmosphere and climate warming.Northeast China is one of the only three black earth belts in the world with rich soil quality.It is Chinese important grain production base.But the soil fertility is declining due to overreclamation.In the northeast soil carbon also show the source of state,whichhad a negative effect on the global carbon cycle.So research on SOC changes of the northeast upland and carbon sequestration ability in the future can accurately grasp the farmland fertility to ensure food security,also it plays an important strategic and realistic significance to sustainable agricultural development and to provide the theoretical foundation for optimization regional environment.The purpose is to understand the global carbon cycle to reduce greenhouse gas emissions and enhance soil carbon content.Based on 6 long-term observation experiment sites data,19 agriculture monitoring continuous observation data and 36 sites data from literature collection,the simulation capability of DAYCENT model on SOC in arid fields in northeast China was verified.Simulated the future changes of SOC for typical sites in black soil.Took the upland SOC?0²0cm?as the research object,the northeast dryland was gridded to 15km×15km,and2064 grids were extracted.DAYCENT model parameters were set,then simulated the futureSOC changes in different tillage managements.Also estimated the solid carbon potential in the northeast China.The results show that:?1?6 long-term observation experiment sites data were used to calibrate and verify the model simulation ability under NPK MNPK SNPK NT four treatments;other 55 sites include19 agriculture monitoring continuous observation data and 36 sites from literature collection data are used to calibrate and verify the DAYCENT wide applicability in the northeast,and make sensitivity analysis on the model.The results show that validation evaluation parameter are in a reasonable range,simulation effect is good,explain DAYCENT model has broad applicability under different management situation in the northeast,the parameters of the model is reasonable.?2?4 types tillage management scenarios from 6 long-term observation sites were set in the future climate conditions to simulate SOC change in black soil district.The results showed that NPK has no significant effect,MNPK have certain effect with the low initial value.At the end of 2100,the SOC increase by 6.07%³2.97%?except Helen?.MNPK also can't restrain the reduce trend of SOC for the high initial content;SNPK and NT have positive effect on SOC promotion in black soil area.At the end of 2100,SOC will increase by 16.78%⁵2.47%?except Helen?under NT SNPK treatments.SOC initial value in Helen site is higher,NT and SNPK can maintain soil fertility.?3?8scenariosin the future climate from 2010a to 2100a were set to simulate SOC changes under 2064 grids in the northeast dry land.SOC simulation effect is NT>INT>SNPK>ISNPK>MNPK>IMNPK>NPK>INPK.Among them NPK and INPK can not maintain the SOC content,the SOC of NT advantage is absolute,compared with the other scenario.The highest average of SOC in northeastis 24.8 g/kg in 2080 with NT scenario,compared with 1980a,increasing by 0.4%.In the region of southern and western in Liaoning province,and Liaohe Plain,includeFuxin,Chaoyang,Dalian and Shenyang,the SOC increased more than 60%under the optimal scenario with low initial value.The SOC still falls down more than 22%in the optimal scenario in Sanjiang plain and eastern mountainous district?include Baishan and Tonghua in Jilin Province,Hegang,Jixi and Shuangyashan in Heilongjiang Province?with higher initial SOC content.The difference value of SOC between the increased irrigation treatment and the original scenario under each scenario was within±1%,but irrigation in the central and western regions?Chaoyang,Tieling,Fushun in Liaoning Province and Baicheng,Songyuan in Jilin Province?has a positive effect on SOC promotion.?4?Analyze the scenarios of maximum SOC in the dry land in the Northeast,and estimate the potential of soil carbon sequestration.The SOC sequestration is 6.49kg/m² in the Northeast,the potential of SOC sequestration is 1.07kg/m².The largest soil carbon storage is2009Tgin the Northeast,the potential SOC storage is 332Tg.The SOC sequestration decreases from east to west and from north to south gradually.The potential carbon sequestration capacity increases from west to eastgradually.Long-term cultivation of black soil has a large carbon sequestration.In forest areas in northern Heilongjiang Province,soil is fertile in Sanjiang Plain and potential carbon sequestration capacity is small.Soil carbon storage is large but the potential carbon storage is the minimum in Heilongjiang province.?5?Carbon sequestration in the periods of 2030a,2050a,2080a,2100a were estimated.SOC density were 5.84kg/m²,6.11kg/m²,6.27kg/m²,6.19kg/m²,respectively.In the northeast,the largest carbon storage in four periods were 1808Tg,1891Tg,1941Tg,1918Tg,respectively,and the potential carbon storage in four periods were 131Tg,214Tg,264Tg,241Tg,respectively,all indexes are the highest level in 2080.SOC in three provinces of Northeast China increase gradually characterized from south to north,west to east.In Sanjiang plain,northeast mountain,and the northern forest,carbon sequestration were high but the potential carbon sequestration ability are limited.It reveals the best scenario for the maximum SOC density corresponding to the best treatmentsin each period at the same time.The maximum value appeared in NT scenario generally in each period.The optimal scenario in western Liaoning Province,Western Jilin Province,Songhua bason and east of Sanjiang plain is INT scenario.