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Development of Regional Nitrogen Rate Guidelines for Intensive Cropping Systems in China
Author(s) -
Cui Zhenling,
Chen Xinping,
Zhang Fusuo
Publication year - 2013
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2012.0398
Subject(s) - sowing , cropping system , rotation system , agronomy , fertilizer , multiple cropping , nitrogen , environmental science , mathematics , zoology , biology , crop , chemistry , organic chemistry
The intensification of agricultural production has been accompanied by an overuse of N fertilization and has accelerated global N consumption in the last 20 yr. We undertook 269 on‐farm demonstration trials to evaluate variations in the optimal N rate (ONR) and developed regional N rate guidelines for intensive wheat ( Triticum aestivum L.)–maize ( Zea mays L.) rotation systems in the North China Plain. Large variations in the ONR (coefficient of variation = 38∼39%) were observed across the 269 fields, resulting from large variations in the initial soil NO 3 –N supply before sowing. A negative linear relationship between the ONR and initial soil NO 3 –N suggested that 1 kg soil NO 3 –N ha –1 was equivalent to applications of 0.54 and 0.71 kg fertilizer N ha –1 for wheat and maize, respectively. The current cropping system, with excessive N inputs and large variations in residual NO 3 –N in the top 90‐cm soil depth (averaging 188 kg N ha –1 season –1 and ranging 20–987 kg N ha –1 season –1 ), could be transformed with optimal N management to a steady state, in which the residual NO 3 –N content is maintained at about 90 to 100 kg N ha –1 . Regional N rate guidelines should be 154 to 159 and 164 to 171 kg N ha –1 for yields of 6 and 9 Mg ha –1 for wheat and maize, respectively. This regional N rate guideline may not be completely accurate but is a robust and simple guideline acceptable to the 100 million smallholder farmers in China.