| In recent years,the black soil region of Northeast China wherever on the plain or slope farmland.Which has faced serious problems of soil erosion,worse physical and chemical properties,soil organic carbon?SOC?loss which have affected the stability of crop yields and the sustainable development of regional agri-ecosystem.This study aims to explore the black soil carbon sequestration and SOC balance under different tillage measures on the plain and loping farmland.Qinggang County,in Suihua City of Heilongjiang province,located the typical black soil belt in Northeast China was figured out as the field experiment sites to monitor in-situ the process of soil carbon and corn growth on the two kind of farmland,plain and slope arable.The effects of different subsoiling combined with straw returning and different ridge tillage on soil physical and chemical properties,soil respiration and organic carbon loss were systematically studied by field in situ test monitoring.It‘s hoped to clarify the soil organic carbon balance of two types of cultivated land.Wish it provides data support for exploring the carbon sequestration effect of soil organic matter upgrading technology in northeast black soil cultivated land,and provides scientific basis for in-depth study of carbon cycle and carbon balance process in black soil cultivated land.The main results are as follows:?1?The SOC content of the straw returning treatment?T1,T3,T4?in the 0-100cm soil layer is5.2%?88.7%higher than that of the farmer's customary treatment?FP?,and the SOC content of the straw returning treatment?T4?is significantly increased by subsoiling 35cm+straw returning treatment?T4?.The soil respiration accumulation was increased by both deep pine and straw returning.The soil respiration accumulation of subsoiling and straw returning treatment?T3 and T4?was increased more significantly.In 2018 and 2019,the soil respiration accumulation was significantly increased by 207.9%and 108.0%than that of FP treatment?2?Straw returning treatment?T1?,subsoiling 25cm+straw return treatment?T3?,subsoiling 35cm+straw returning treatment?T4?increase carbon income by 488.5%,477.7%and 448.9%respectively compared with FP treatment,which is beneficial to organic carbon sequestration;while the soil organic carbon balance of T2 treatment shows that it can't make ends meet,increasing carbon expenditure by102.3%compared with FP.?3?The treatment of single straw returning?T1?,single subsoiling?T2?and subsoiling+straw returning?T3,T4?treatments can significantly increase corn yield by 13.8%?24.7%compared to FP which reaching 12 t·ha-1 high production level.Without fertilization,the yield was significantly reduced by 25.0%?45.3%than FP?P<0.05?.Subsoiling combined with straw returning to the field can effectively increase crop yield?4?The experimental results of sloping farmland showed that SOC content in different soil depth under the conditions of parallel ridge and cross-ridge tillage showed similar rule of slope toe>slope top>slope back>slope shoulder.After 2 years of experiment,except for 20-40cm slope toe area,SOC content of cross-ridge tillage increased by 2.1%?12.4%in different slope positions compared with longitudinal ridge?P>0.05?.?5?The cumulative amount of soil respiration on the cross-ridge tillage was higher than longitudinal ridge by 2.8%?12.1%?P>0.05?,but the difference was not significant.From different slope positions,in 2018 and 2019 years,the cumulative amount of soil respiration on the cross-ridge tillage slope top,shoulder and back was higher 1.0%?1.4%,22.4%?50.2%,1.3%?12.7%respectively than longitudinal ridge.But lower than longitudinal ridge 9.2%?9.5%?P>0.05?In the sedimentary area?slope toe?.?6?Cross-ridge tillage at the slope toe reduces runoff loss by 99.8%effectively,sediment loss by99.9%,and reduce SOC by 99.9%and DOC by 98.9%effectively.SOC in surface runoff was the main factor in carbon migration and loss in sloping farmland.DOC accounted for 1.1%?35.6%of total carbon migration and loss.?7?Cross-ridge tillage can reduce the soil organic carbon expenditure.Except for the slope shoulder,cross-ridge tillage has 0.46%,2.26%and 15.43%less carbon expenditure on the top,back and toe of the slope than longitudinal ridge.In 2018 and 2019 years,the yield of Cross-ridge tillage corn was significantly higher than longitudinal ridge about 21.4%?P<0.05?which the overall corn yield was mainly increased by increasing the yield of the eroded area. |
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