Fate of 15N-labelled urea as affected by long-term manure substitution

Fuyue Dai; Bingqian Fan; Jungai Li; Yitao Zhang; Hongyuan Wang; Zhen Wang; Muhammad Amjad Bashir; Golnaz Ezzati; Limei Zhai; Hong J Di; Hongbin Liu

doi:10.1016/j.scitotenv.2023.164924

Fate of ¹⁵N-labelled urea as affected by long-term manure substitution

Sci Total Environ. 2023 Oct 1:893:164924. doi: 10.1016/j.scitotenv.2023.164924. Epub 2023 Jun 15.

Authors

Affiliations

¹ State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Key Laboratory of Non-point Source Pollution Control, Ministry of Agriculture and Rural Affairs, Changping Soil Quality National Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China.
² Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, PR China.
³ State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Key Laboratory of Non-point Source Pollution Control, Ministry of Agriculture and Rural Affairs, Changping Soil Quality National Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China. Electronic address: wanghongyuan@caas.cn.
⁴ Department of Agronomy, Engro Fertilizers Limited, Lahore, Pakistan.
⁵ Teagasc, Environmental Research Centre, Johnstown Castle, Wexford, Ireland.

PMID: 37327900
DOI: 10.1016/j.scitotenv.2023.164924

Abstract

Quantifying the fate of fertilizer nitrogen (N) is essential to develop more sustainable agricultural fertilization practices. However, the fate of chemical fertilizer N, particularly in long-term manure substitution treatment regimes, is not fully understood. The present study aimed to investigate the fate of ¹⁵N-labelled urea in a chemical fertilizer treatment (CF, 240 kg ¹⁵N ha^-1) and N manure 50 % substitution treatment (1/2N + M, 120 kg ¹⁵N ha^-1 + 120 kg manure N ha^-1) in two continuous crop seasons, based on a 10-year long-term experiment in the North China Plain (NCP). The results showed that manure substitution greatly enhanced ¹⁵N use efficiency (¹⁵NUE) (39.9 % vs. 31.3 %) and suppressed ¹⁵N loss (6.9 % vs. 7.5 %) compared with the CF treatment in the first crop. However, the N₂O emissions factor in the 1/2N + M treatment was increased by 0.1 % (0.5 kg ¹⁵N ha^-1 for CF vs. 0.4 kg ¹⁵N ha^-1 for 1/2N + M) compared with the CF treatment, although N leaching and NH₃ volatilization rates decreased by 0.2 % (10.8 kg ¹⁵N ha^-1 for CF vs. 5.1 kg ¹⁵N ha^-1 for 1/2N + M) and 0.5 % (6.6 kg ¹⁵N ha^-1 for CF vs. 2.8 kg ¹⁵N ha^-1 for 1/2N + M), respectively. In which, only NH₃ volatilization presented significantly difference between treatments. It is important to note that in the second crop, the residual ¹⁵N in soil (0-20 cm) remained mostly in the soil for the CF (79.1 %) and the 1/2N + M treatment (85.3 %), and contributed less to crop N uptake (3.3 % vs. 0.8 %) and leached losses (2.2 % vs. 0.6 %). This proved that manure substitution could enhance the stabilization of chemical N. These results suggested that long-term manure substitution effectively increases NUE, suppresses N loss, and improves N stabilization in soil, but negative impacts such as N₂O emissions due to climate change should be investigated further.

Keywords: Fate of (15)N-labelled urea; Manure substitution; N use efficiency; Reactive N losses.