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Optimized straw interlayer improves organic carbon and total nitrogen in soil profile: A four-year experiment in a saline soil
  • +7
  • Fangdi Chang,
  • Xiquan Wang,
  • Jiashen Song,
  • Hongyuan Zhang,
  • Ru Yu,
  • Jing Wang,
  • Jian Liu,
  • Shang Wang,
  • Hongjie Ji,
  • Li Yuyi
Fangdi Chang
Chinese Academy of Agricultural Sciences Institute of Agricultural Resources and Regional Planning

Corresponding Author:[email protected]

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Xiquan Wang
Chinese Academy of Agricultural Sciences Institute of Agricultural Resources and Regional Planning
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Jiashen Song
Chinese Academy of Agricultural Sciences Institute of Agricultural Resources and Regional Planning
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Hongyuan Zhang
Chinese Academy of Agricultural Sciences Institute of Agricultural Resources and Regional Planning
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Ru Yu
Chinese Academy of Agricultural Sciences Institute of Agricultural Resources and Regional Planning
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Jing Wang
Chinese Academy of Agricultural Sciences Institute of Agricultural Resources and Regional Planning
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Jian Liu
The Norwegian Institute of Bioeconomy Research (NIBIO) PO Box 115 1431 As Norway
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Shang Wang
Department of Soil and Plant Microbiome Institute of Phytopathology Christian-Albrechts-University of Kiel 24118 Kiel Germany
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Hongjie Ji
Chinese Academy of Agricultural Sciences Institute of Agricultural Resources and Regional Planning
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Li Yuyi
Chinese Academy of Agricultural Sciences Institute of Agricultural Resources and Regional Planning
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Abstract

Soil salinization is a critical environmental issue restricting agricultural production. Straw deep returning as interlayer (40 cm) has been a popularized practice to alleviate salt stress. However, the legacy effects of straw interlayer associated with the straw input amount on soil organic carbon (SOC) and total nitrogen (TN) in saline soil remain unclear. Therefore, a four-year (2015-2018) field experiment was conducted with four levels (i.e., 0, 6, 12 and 18 Mg ha -1) of straw returning as interlayer. Compared with no straw interlayer (CK), straw interlayers increased SOC content by 14-32% and 11-57% in 20-40 cm and 40-60 cm, respectively. Lower increases were for soil TN content (8-22% in 20-40 cm and 6-34% in 40-60 cm) than SOC content, which led to increase soil C:N ratio in the 20-60 cm soil depth. Compared with CK, remarkable increases of SOC and soil TN contents in 20-60 cm led to the decrease of stratification ratios (0-20: 20-60 cm), which promoted uniform distributions of SOC and TN in soil profiles. Even though soil parameters ranged widely according to the straw input, straw interlayer with 12 Mg ha -1 had higher SOC, TN, C:N ratio, and lower soil stratification ratio in 2015-2017, which contributed to salt leaching, water retention, and yield increment. These results highlighted the legacy effects of straw interlayers maintained more than four years, which led to an underestimation for previous short-term experiments, and demonstrated a great potential for subsoil fertility and salt-affected soil amelioration.