Pedosphere 17(1): 52--61, 2007
ISSN 1002-0160/CN 32-1315/P
©2007 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Fate of 15N-labeled urea under a winter wheat-summer maize rotation on the North China Plain |
JU Xiao-Tang1 , LIU Xue-Jun1, PAN Jia-Rong1,2 and ZHANG Fu-Suo1 |
1 Key Laboratory of Plant-Soil Interactions, Ministry of Education College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094(China). E-mail: juxt@cau.edu.cn
2 Institute of Application of Atomic Energy, Chinese Academy of Agricultural Science, Besting 100094 (China) |
| ABSTRACT |
| A field experiment was conducted to investigate the fate of 15N-labeled urea and its residual effect under the winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) rotation system on the North China Plain. Compared to a conventional application rate of 360 kg N ha-1 (N360), a reduced rate of 120 kg N ha-1 (N120) led to a significant increase (P < 0.05) in wheat yield and no significant differences were found for maize. However, in the 0-100 cm soil profile at harvest, compared with N360, N120 led to significant decreases (P < 0.05) of percent residual N and percent unaccounted-for N, which possibly reflected losses from the managed system. Of the residual fertilizer N in the soil profile, 25.6%-44.7% and 20.7%-38.2% for N120 and N360, respectively, were in the organic N pool, whereas 0.3%-3.0% and 11.2%-24.4%, correspondingly, were in the nitrate pool, indicating a higher potential for leaching loss associated with application at the conventional rate. Recovery of residual N in the soil profile by succeeding crops was less than 7.5% of the applied N. For N120, total soil N balance was negative; however, there was still considerable mineral N (NH4+-N and NO3--N) in the soil profile after harvest. Therefore, N120 could be considered agronomically acceptable in the short run, but for long-term sustainability, the N rate should be recommended based on a soil mineral N test and a plant tissue nitrate test to maintain the soil fertility. |
| Key Words: 15N-labeled urea, nitrogen recovery, nitrogen residual effect, North China Plain, winter wheat-summer maize rotation |
| Citation: Ju, X. T., Liu, X. J., Pan, J. R. and Zhang, F. S. 2007. Fate of 15N-labeled urea under a winter wheat-summer maize rotation on the North China Plain. Pedosphere. 17(1): 52-61. |
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