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Acta Prataculturae Sinica ›› 2021, Vol. 30 ›› Issue (2): 32-45.DOI: 10.11686/cyxb2020226

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Effects of alternative fertilizer options on soil CO2 emission and carbon pool management index in a dryland soil

Xiao-jiao WANG1,3(), Li-qun CAI1,2,4(), Peng QI1,2,4(), Ya-zhi Wang1, Xiao-long CHEN1, Jun Wu1,2,4, Ren-zhi ZHANG1,2,4()   

  1. 1.College of Resources and Environmental Sciences,Gansu Agricultural University,Lanzhou 730070,China
    2.Gansu Provincial Key Laboratory of Arid Land Crop Science,Gansu Agricultural University,Lanzhou 730070,China
    3.College of Management,Gansu Agricultural University,Lanzhou 730070,China
    4.Gansu Engineering Research Center for Agriculture Water-saving,Lanzhou 730070,China
  • Received:2020-05-21 Revised:2020-07-29 Online:2021-02-20 Published:2021-01-19
  • Contact: Li-qun CAI,Peng QI,Ren-zhi ZHANG

Abstract:

In 2015, the Ministry of Agriculture in China announced a ‘zero increase action plan’ for national fertilizer use, to be implemented by 2020, with the aim of reducing the environmental costs associated with food production. This ‘zero increase’ plan highlights the need to adopt reasonable fertilizer policies with organic materials to alleviate the environmental problems (e.g., global warming, air pollution, and eutrophication). Hence, this research aimed to clarify the influence of various fertilization options on soil CO2 emission and carbon pool management index under different fertilization options. Collection of such data is an essential component of research on carbon sequestration and carbon emission reduction and is also necessary to identify best fertilization practice in unirrigated farming on the Loess Plateau. A long-term field experiment with five fertilization treatments in the Longzhong Loess Plateau was set up in 2012. Fertilization treatments included no fertilizer (CK), nitrogen fertilizer (NF), organic fertilizer (OM), straw (ST), and organic fertilizer combined with inorganic fertilizer (OMNF). The annual soil CO2 emissions, crop carbon emission efficiency (CEE) and carbon pool management index (CPMI) were analyzed in 2018, and the relationships between relevant factors [soil temperature, moisture content, microbial biomass carbon and nitrogen (MBC, MBN), readily oxidizable organic carbon (ROOC), urease and invertase for the soil depth of 0-30 cm] and soil CO2 flux were determined by the structural equation model (SEM). It was found that: 1) Compared with CK, ST, OMNF and OM treatments increased the soil CO2 flux by 42.72%, 30.82% and 29.79%, respectively, while ST and OM treatments increased the soil CO2 emission by 36.35%, 32.45%(P<0.05), respectively, and OMNF reduced carbon emission efficiency by 41.10% (P<0.05). 2) The OM treatment significantly increased the soil ROOC, MBC, MBN, invertase activity and CPMI in the 0-5 cm soil layer. Compared with CK and NF, the OMNF treatment significantly increased the soil CPMI (0-30 cm) by 127.41% and 99.33% (P<0.05), respectively. 3) SEM showed that the environmental factors explained in total 53% of soil CO2 flux, and the factors that had the largest cumulative effect were soil temperature (2.36), microbial biomass carbon (1.59) and soil moisture content (1.18). These three factors also indirectly affected soil CO2 flux. Higher soil temperature promoted increased MBC and invertase activity, and increased MBC further enhanced the rate of change of MBN and ROOC. Overall, OMNF was found to be a sustainable and effective management practice to improve CPMI, maintain microbial activity, increase crop yield, and at the same time also reduce CEE in dryland farming on the Loess Plateau.

Key words: dry land soil, CO2 emission, crop carbon emission efficiency, carbon pool management index, fertilization options