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The Ecologically Optimum Application of Nitrogen in Wheat Season of Rice–Wheat Cropping System
Author(s) -
Liang X. Q.,
Li H.,
He M. M.,
Chen Y. X.,
Tian G. M.,
Xu S. Y.
Publication year - 2008
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/agronj2006.0191
Subject(s) - agronomy , leaching (pedology) , lysimeter , environmental science , oryza sativa , leachate , cropping system , nitrogen , field experiment , growing season , fertilizer , cropping , crop , mathematics , biology , chemistry , soil water , agriculture , soil science , ecology , organic chemistry , biochemistry , gene
Because excessive application of N fertilizer for crop production leads to environmental pollution and low N utility efficiency, a better understanding of the effects of N application rates on crop yields and NO 3 –N leaching is required for developing optimum ecological N management that reduces NO 3 –N leaching while keeping crop yield. Field experiments at two sites in the Taihu region of China were conducted to study the ecologically optimum application of N in wheat ( Triticum aestivum L.) season of rice ( Oryza sativa L.)–wheat cropping system. The experiment at either site had five N rates on wheat (0–360 kg N ha −1 in 90‐kg increments) and NO 3 –N in leachate were collected by wedge‐shaped fiberglass wick lysimeters. At either site, the N‐wheat yield quadratic response curve was fitted quite well and a significantly linear relationship between N rates and seasonal NO 3 –N masses in leachate was also found. The calculated economically optimum N rate for wheat was more site related than depending on changing growing conditions from year to year, while the ecologically optimum N rate was significantly different both at sites and growing conditions ( P = 0.01). The results suggest that applying the ecologically optimum N rates of 120–180 kg N ha −1 to wheat is beneficial for maximally reducing NO 3 –N leaching loss but minimally decreasing yield.