Crop straw incorporation alleviates overall fertilizer-N losses and mitigates N2O emissions per unit applied N from intensively farmed soils: An in situ 15N tracing study

Cong Xu; Xiao Han; Yuping Zhuge; Guangmin Xiao; Bang Ni; Xiuchun Xu; Fanqiao Meng

doi:10.1016/j.scitotenv.2020.142884

Crop straw incorporation alleviates overall fertilizer-N losses and mitigates N₂O emissions per unit applied N from intensively farmed soils: An in situ ¹⁵N tracing study

Sci Total Environ. 2021 Apr 10:764:142884. doi: 10.1016/j.scitotenv.2020.142884. Epub 2020 Oct 14.

Authors

Cong Xu¹, Xiao Han², Yuping Zhuge³, Guangmin Xiao⁴, Bang Ni⁴, Xiuchun Xu⁴, Fanqiao Meng⁵

Affiliations

¹ Scientific Observation and Experimental Station of Arable Land Conservation of Jiangsu Province, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; Beijing Key Laboratory of Biodiversity and Organic Farming, Beijing Key Laboratory of Farmland Soil Pollution Prevention and Remediation, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
² Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China.
³ National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian 271018, China.
⁴ Beijing Key Laboratory of Biodiversity and Organic Farming, Beijing Key Laboratory of Farmland Soil Pollution Prevention and Remediation, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
⁵ Beijing Key Laboratory of Biodiversity and Organic Farming, Beijing Key Laboratory of Farmland Soil Pollution Prevention and Remediation, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China. Electronic address: mengfq@cau.edu.cn.

PMID: 33757238
DOI: 10.1016/j.scitotenv.2020.142884

Abstract

A thorough elucidation of the coupled effects of N fertilization and straw incorporation on N₂O emissions and N losses is crucial for alleviating negative environmental impacts in intensively farmed regions. Here, we conducted an in situ ¹⁵N tracing experiment to assess the source of N₂O emissions and fate of fertilizer-N in soil intensively farmed with summer maize (Zea mays L.). Four treatments, i.e., no N fertilization and no straw incorporation (N0S0), straw incorporation only (N0S1), N fertilization only (N1S0), and N fertilization plus straw incorporation (N1S1), were established in the study. Compared with straw removal, straw incorporation increased the seasonal N₂O emissions by 22.3% but reduced the N₂O emissions per unit of applied N by 6.22% (P > 0.05). The emission of fertilizer-derived N₂O occurred mainly in the 13-17 days after fertilization; thereafter, the ratio of fertilizer-derived N₂O fluxes would be less than 5%. N fertilization significantly stimulated non-fertilizer-derived N₂O emissions and soil CO₂ fluxes, especially when straw was incorporated (P < 0.05), indicating that N fertilization might have triggered the mineralization of straw-N and/or native soil organic N. The soil NO₃^--N concentration in straw-incorporated plots tended to be lower than that in straw-removed plots, especially after N fertilization events. Straw incorporation sequestered 52.5% (27.4 kg N ha^-1) more fertilizer-N in 1 m of soil than straw removal (P < 0.05) while significantly increasing the fertilizer-N harvest index and maintaining grain yield. Overall, compared with straw removal, straw incorporation significantly reduced total fertilizer-N losses (by 12.8%, i.e., 14.58 kg N ha^-1; P < 0.05). Our study highlights the benefits of straw incorporation for increasing in-season and multiseason fertilizer-N use efficiencies and alleviating fertilizer-N-induced environmental costs in intensively farmed regions.

Keywords: (15)N tracing; Intensive farming; Nitrogen fertilization; Nitrogen loss; Nitrous oxide; Straw incorporation.