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Chinese Journal of Applied Ecology ›› 2021, Vol. 32 ›› Issue (8): 2703-2712.doi: 10.13287/j.1001-9332.202108.030

• Special Features of Conservation Tillage • Previous Articles     Next Articles

Soil organic and inorganic carbon pools as affected by straw return modes under a wheat-maize rotation system in the Guanzhong Plain, Northwest China

LI Yu-nuo1,2, FAN Yuan-yuan1,2, CAO Bin-bin1,2, TIAN Xiao-hong1,2,3*, SHI Jiang-lan1,2   

  1. 1College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, Shaanxi, China;
    2Key Laboratory of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China;
    3Scientific Observing and Experimental Station of Arable Land Conservation (Heyang), Ministry of Agriculture, Heyang 715300, Shaanxi, China
  • Received:2021-01-07 Accepted:2021-05-31 Online:2021-08-15 Published:2022-02-15
  • Contact: *E-mail: txhong@nwsuaf.edu.cn
  • Supported by:
    National Key Research and Development Program of China (2016YFD0200308), the Key Research and Development Program of Shaanxi Province (2019ZDLNY01-05-01) and Key Project of the National Science & Technology Pillar Program (2012BAD14B11).

Abstract: To understand the effects of straw return modes on soil carbon pools, we investigated total soil organic carbon (SOC), labile organic carbon fractions, and inorganic carbon (SIC) in different straw return modes at a depth of 0-40 cm under a maize-wheat cropping system in the Guanzhong Plain, Shaanxi, based on an 11-year field experiment. There were five straw return modes, i.e., no return of straw of both wheat and maize (CK), the retention of high wheat stubble plus the return of chopped maize straw (WH-MC), the return of both chopped wheat and maize straw (WC-MC), the retention of high wheat stubble and no return of maize straw (WH-MN), and the return of chopped wheat straw and no return of maize straw (WC-MN). The proportions of SOC storage were significantly higher under the WH-MC and WC-MC treatments than that under the CK by 28.1% and 22.2%, respectively. The proportions of SIC storage were increased by 20.4% and 17.3%, respectively. Compared with the initial value, the increases of sequestered SOC and SIC ranged from -0.84 t·hm-2 to 6.55 t·hm-2, respectively, and from -0.26 t·hm-2 to 8.61 t·hm-2, respectively. The efficiency of sequestration of SOC was 7.5%. To maintain the basic SOC level, the minimum carbon input from straw was 4.65 t·hm-2·a-1. The contents of labile carbon fractions at the 0-20 cm layer increased significantly under the WH-MC and WC-MC treatments compared with those of the control. Results of principal component analysis showed that the changes in soil carbon pools were primarily affected by the amount of straw return. Additionally, the increases in SIC storage could be ascribed to the Ca2+ and Mg2+ ions derived from irrigation water and plant residues that could coprecipitate with the CO2 from SOC mineralization to form CaCO3. In conclusion, our results indicated that the straw return mode that utilized the retention of high wheat stubble and chopped maize straw was sufficient to maintain soil carbon storage and would be the optimal straw-returning strategy for the region.

Key words: straw return mode, soil organic carbon (SOC), soil inorganic carbon (SIC), soil carbon sequestration