Effects of subsoiling year on soil organic carbon content and humic acid structure characteristics under maize straw mulching and returning
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DOI:10.7606/j.issn.1000-7601.2024.01.21
Key Words: maize straw mulching and returning  subsoiling  soil organic carbon  humic acid  three\|dimensional fluorescence spectroscopy
Author NameAffiliation
GAO Pan Qiqihar Branch of Heilongjiang Academy of Agricultural Sciences, Qiqihar, Heilongjiang 161006, China 
WANG Yuxian Qiqihar Branch of Heilongjiang Academy of Agricultural Sciences, Qiqihar, Heilongjiang 161006, China 
CAI Shanshan Heilongjiang Province Black Soil Protection and Utilization Research Institute, Harbin, Heilongjiang 150086, China 
XU Yingying Qiqihar Branch of Heilongjiang Academy of Agricultural Sciences, Qiqihar, Heilongjiang 161006, China 
YANG Huiying Qiqihar Branch of Heilongjiang Academy of Agricultural Sciences, Qiqihar, Heilongjiang 161006, China 
WANG Chen Qiqihar Branch of Heilongjiang Academy of Agricultural Sciences, Qiqihar, Heilongjiang 161006, China 
ZHANG Gongliang Qiqihar Branch of Heilongjiang Academy of Agricultural Sciences, Qiqihar, Heilongjiang 161006, China 
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Abstract:
      To clarify the changes in soil organic carbon components under different straw return tillage measures, this study was based on a 6-year long\|term positioning experiment with straw return. Using three\|dimensional fluorescence spectroscopy technology and in the conditions of CK (non\|subsoiling and no straw returning), NFG (non\|subsoiling and straw returning), EFG (subsoiling every other year and straw returning), TFG (every two years of subsoiling+straw returning) and SFG (consecutive years of subsoiling+straw returning), the content of soil organic carbon (SOC) and structural characteristics of humic acid (HA) were analyzed. The results showed that compared with CK, the SOC, HA content and PQ value of the 0~10 cm soil layer treated with EFG significantly increased by 25.23%, 16.19%, and 4.27%, respectively, while the FA content decreased by 4.55%. In the soil layer of 10~20 cm, EFG treatment had the highest SOC content, which increased by 13.18% compared to CK. The HA and FA content of SFG treatment increased the most compared to CK, with an increase of 13.27% and 32.74%, respectively. Through the 3D fluorescence spectrum of HA, it was found that compared with CK (Ex/Em=270/455,270/460), the HA fluorescence peak wavelength in the 0~10 cm and 10~20 cm soil layers under EFG (Ex/Em=280/455,270/465) treatment showed a red shift phenomenon. Soil humic acid contains two components, C1 (Ex/Em=270/280) and C2 (Ex/Em=440/515), which were both humic acid like substances. Humic acid had a high degree of overall humification and a complex structure. The C2 component treated with EFG and TFG accounted for the highest proportion, with 28.59% and 31.38%, respectively. The Fmax values of C1 and C2 components in each treatment increased compared to CK, indicating an increase in humification degree. In summary, EFG treatment (subsoiling every other year and straw returning) enhanced the content of soil organic carbon and humic acid substances, increased the degree of humification, and strengthened the soil’s fertilizer supply capacity, making it a better cultivation technical measure in the black soil area of Heilongjiang.