Pedosphere 15(5): 641--645, 2005
ISSN 1002-0160/CN 32-1315/P
©2005 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Nitrogen leaching in vegetable fields in the suburbs of Shanghai
CAO Lin-Kui, CHEN Guo-Jun and LU Yi-Tong
School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 201101 (China). E-mail: clk@sjtu.edu.cn
ABSTRACT
      Nitrogen (N) leaching in vegetable fields from December 2002 to May 2003 with equal dressings of total N for a sequential rotation of Chinese flat cabbage (Brassica chinensis L. var. rosularis) and lettuce (Lactuca sativa L.) in a suburban major vegetable production base of Shanghai were examined using the lysimeter method to provide a scientific basis for rational utilization of nitrogen fertilizers so as to prevent nitrogen pollution of water resources. Results showed that leached N consisted mainly of nitrate N, which accounted for up to more than 90% of the total N loss and could contribute to groundwater pollution. Data also showed that by partly substituting chemical N (30%) in a basal dressing with equivalent N of refined organic fertilizer in the Chinese flat cabbage field, 64.5% of the leached nitrate N was reduced, while in the lettuce (Lactuca sativa L.) field, substituting 1/2 of the chemical N in a basal dressing and 1/3 of the chemical N in a top dressing with equivalent N of refined organic fertilizers reduced 46.6% of the leached nitrate N. In the two-year sequential rotation system of Chinese flat cabbage and lettuce, nitrate-N leaching in the treatment with the highest amount of chemical fertilizer was up to 46.55 kg ha-1, while treatment plots with the highest amount of organic fertilizer had only 17.58 kg ha-1. Thus, partly substituting refined organic fertilizer for chemical nitrogen in the first two seasons has a great advantage of reducing nitrate-N leaching.
Key Words:  leaching loss, nitrogen, organic fertilizer, vegetable field
Citation: Cao, L. K., Chen, G. J. and Lu, Y. T. 2005. Nitrogen leaching in vegetable fields in the suburbs of Shanghai. Pedosphere. 15(5): 641-645.
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