The effects of long term no-tillage on the chemical composition of soil organic matter

小姐 Qiqi Gao1, Mr Zhangliu Du1

1Institute Of Environment And Sustainable Development In Agriculture, Chinese Academy Of Agricultural Sciences, Beijing, China

No-tillage is considered as a potential measure to improve soil organic matter (SOM). In this study, we focused on the impact of different tillage practices on the chemical composition of SOM at molecular level based on a 17-year no-tillage field experiment in the North China. Soil samples were collected from 0-10 cm soil layer under three tillage treatments, including conventional tillage with straw incorporation (CT), rotary tillage with straw application (RT) and no-tillage with straw mulching (NT). Then, solvent extraction and CuO oxidation were used to characterize free compounds and lignin-derived phenols. The results showed that the concentrations of total n-alkanols were increased by 40.7% under NT and 15.5% under RT compared with CT, and the n-alkanols under NT was higher by 21.8% than that of RT. As for the total carbohydrates, NT increased by 66.9% but RT decreased by 58.6% relative to CT, whereas NT had 3.04 times higher carbohydrates than RT. In contrast, the short-chain n-alkanoic acids (<C20) concentrations under NT were lower by 15.1% than that of CT, while the long-chain n-alkanoic acids (≥C20) concentrations under RT were higher by 13.2% than that of CT. Overall, NT significantly decreased the n-alkanoic acids by 25.0% compared with RT. Moreover, the concentrations of lignin monomers under NT and RT were increased by 55.7% and 32.1% than that of CT, while NT had 17.9% higher lignin monomers concentrations than RT in the 0-10 cm soil layer. The lignin degradation was reflected by elevated ratios of syringic acid to syringaldehyde ((Ad/Al)s) and vanillic acid to vanillin ((Ad/Al)v). The (Ad/Al)s under NT was lower than that of CT and RT, while no significant changes in (Ad/Al)v were observed between treatments . We concluded that shifting from conventional tillage to no-tillage changed the chemical composition of SOM under the experimental condition.


Biography: My research interests lie in the field of terrestrial soil organic matter (SOM) biogeochemistry. I am interested in the mechanisms and process that act to stabilize and destabilize SOM in surface soils. Currently, I focus on the feedbacks between the management options (e.g., tillage, residues, manure, and biochar) and SOM transformations.

SOIL ORGANIC MATTER

7th International Symposium
Soil Organic Matter

6 – 11 October 2019

Hilton Adelaide

Adelaide, South Australia

Australia

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