Document Detail

Reducing environmental risk by improving N management in intensive Chinese agricultural systems.
MedLine Citation:
PMID:  19223587     Owner:  NLM     Status:  MEDLINE    
Excessive N fertilization in intensive agricultural areas of China has resulted in serious environmental problems because of atmospheric, soil, and water enrichment with reactive N of agricultural origin. This study examines grain yields and N loss pathways using a synthetic approach in 2 of the most intensive double-cropping systems in China: waterlogged rice/upland wheat in the Taihu region of east China versus irrigated wheat/rainfed maize on the North China Plain. When compared with knowledge-based optimum N fertilization with 30-60% N savings, we found that current agricultural N practices with 550-600 kg of N per hectare fertilizer annually do not significantly increase crop yields but do lead to about 2 times larger N losses to the environment. The higher N loss rates and lower N retention rates indicate little utilization of residual N by the succeeding crop in rice/wheat systems in comparison with wheat/maize systems. Periodic waterlogging of upland systems caused large N losses by denitrification in the Taihu region. Calcareous soils and concentrated summer rainfall resulted in ammonia volatilization (19% for wheat and 24% for maize) and nitrate leaching being the main N loss pathways in wheat/maize systems. More than 2-fold increases in atmospheric deposition and irrigation water N reflect heavy air and water pollution and these have become important N sources to agricultural ecosystems. A better N balance can be achieved without sacrificing crop yields but significantly reducing environmental risk by adopting optimum N fertilization techniques, controlling the primary N loss pathways, and improving the performance of the agricultural Extension Service.
Xiao-Tang Ju; Guang-Xi Xing; Xin-Ping Chen; Shao-Lin Zhang; Li-Juan Zhang; Xue-Jun Liu; Zhen-Ling Cui; Bin Yin; Peter Christie; Zhao-Liang Zhu; Fu-Suo Zhang
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-02-17
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  106     ISSN:  1091-6490     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2009 Mar 
Date Detail:
Created Date:  2009-03-04     Completed Date:  2009-04-01     Revised Date:  2013-06-02    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3041-6     Citation Subset:  IM    
Key Laboratory of Plant and Soil Interactions, Ministry of Education, China, and College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
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MeSH Terms
Agriculture / methods*
Crops, Agricultural
Nitrogen / chemistry*
Reg. No./Substance:
Erratum In:
Proc Natl Acad Sci U S A. 2009 May 12;106(19):8077

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