Sugarcane/soybean intercropping with reduced nitrogen addition promotes photosynthesized carbon sequestration in the soil

Tantan Zhang; Hu Tang; Peng Peng; Shiqiang Ge; Yali Liu; Yuanjiao Feng; Jianwu Wang

doi:10.3389/fpls.2023.1282083

Sugarcane/soybean intercropping with reduced nitrogen addition promotes photosynthesized carbon sequestration in the soil

Front Plant Sci. 2023 Dec 1:14:1282083. doi: 10.3389/fpls.2023.1282083. eCollection 2023.

Authors

Tantan Zhang^{1

2

3}, Hu Tang^{1

2

3}, Peng Peng^{1

2

3}, Shiqiang Ge^{1

2

3}, Yali Liu^{1

2

3}, Yuanjiao Feng^{1

2

3}, Jianwu Wang^{1

2

3}

Affiliations

¹ Key Laboratory of Agro-Environments in Tropics, Ministry of Agriculture and Rural Affairs, South China Agriculture University, Guangzhou, China.
² Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, South China Agriculture University, Guangzhou, China.
³ Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, China.

Abstract

Introduction: Sugarcane/soybean intercropping with reduced nitrogen (N) addition has improved soil fertility and sustainable agricultural development in China. However, the effects of intercropping pattern and N fertilizer addition on the allocation of photosynthesized carbon (C) in plant-soil system were far less understood.

Methods: In this study, we performed an ¹³CO₂ pulse labeling experiment to trace C footprints in plant-soil system under different cropping patterns [sugarcane monoculture (MS), sugarcane/soybean intercropping (SB)] and N addition levels [reduced N addition (N1) and conventional N addition (N2)].

Results and discussion: Our results showed that compared to sugarcane monoculture, sugarcane/soybean intercropping with N reduced addition increased sugarcane biomass and root/shoot ratio, which in turn led to 23.48% increase in total root biomass. The higher root biomass facilitated the flow of shoot fixed ¹³C to the soil in the form of rhizodeposits. More than 40% of the retained ¹³C in the soil was incorporated into the labile C pool [microbial biomass C (MBC) and dissolved organic C (DOC)] on day 1 after labeling. On day 27 after labeling, sugarcane/soybean intercropping with N reduced addition showed the highest ¹³C content in the MBC as well as in the soil, 1.89 and 1.14 times higher than the sugarcane monoculture, respectively. Moreover, intercropping pattern increased the content of labile C and labile N (alkaline N, ammonium N and nitrate N) in the soil. The structural equation model indicated that the cropping pattern regulated ¹³C sequestration in the soil mainly by driving changes in labile C, labile N content and root biomass in the soil. Our findings demonstrate that sugarcane/soybean intercropping with reduced N addition increases photosynthesized C sequestration in the soil, enhances the C sink capacity of agroecosystems.

Keywords: 13C pulse labelling; C cycle; root growth; soil biochemistry; sugarcane/soybean intercropping.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study was supported by the China National Key R&D Program during the 14th Five-year Plan Period (Grant Nos. 2022YFD1901603). The authors would like to thank SPRINGER NATURE for its linguistic assistance during the preparation of this manuscript. We are also very grateful to Xingyuan Chen for helping us to manage the pot experiment.