Continuous planting of cotton after reclamation alters the humus composition and humic acid structural characteristics
2022
Zhang, Jun | Zhang, Fenghua
The structural characteristics of soil organic matter (SOM) play an important role in improving soil organic carbon (SOC) sequestration capacity and maintaining soil fertility levels. This study selected saline - alkaline abandoned farmland as a control (0a), and cotton fields were continuously planted for 5, 10, 15, 20 and 25 years after reclamation. The results showed that the lowest soil electrical conductivity and total nitrogen are found in 0a, the highest pH (5a) and Available potassium content are found in 0a. SOC and humus contents were significantly increased by reclamation, which showed a trend of first increase and then decrease, and the highest value was observed in continuous cropping cotton 10a. In addition, the SOM is basically aliphatic. When the cotton field was continuously planted for 15a. Alkyl C: O-alkyl C and hydrophobicity index were the highest, indicating that the alkylation degree of SOM was high, the decomposition ability was strong, and the stability was improved. These results provide guidance for our study of SOM in different cotton continuous cropping systems and will provide insights into the dynamics pathways of humus substances stabilisation in northwest China.
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