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Chlorophyll meter–based nitrogen fertilizer optimization algorithm and nitrogen nutrition index for in‐season fertilization of paddy rice
Author(s) -
Zhang Ke,
Yuan Zhaofeng,
Yang Tiancheng,
Lu Zhenzhou,
Cao Qiang,
Tian Yongchao,
Zhu Yan,
Cao Weixing,
Liu Xiaojun
Publication year - 2020
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 - 10.1002/agj2.20036
Subject(s) - fertilizer , nitrogen , mathematics , human fertilization , cultivar , field experiment , agronomy , nitrogen fertilizer , yield (engineering) , zoology , biology , chemistry , statistics , materials science , organic chemistry , metallurgy
Nitrogen fertilizer optimization algorithm (NFOA) and nitrogen nutrition index (NNI) have been developed to achieve higher yield and N use efficiency. This study was to improve NFOA and NNI strategies for managing rice N nutrition based on portable Soil and Plant Analyzer Development (SPAD) meter. Four field experiments were conducted in 2013–2014 to generate diverse N fertilizer rates in rice cultivars at three eco‐sites. Nitrogen indicators SPAD readings were measured to establish SPAD‐based management strategies. Two experiments were conducted to assess the effectiveness of developed NFOA and NNI algorithm for upward and downward adjustment of N‐fertilizer doses twice within the growing season in 2015. New N‐adjustment strategies optimized N topdressing by upward‐, fine‐, and downward‐ adjustment with an average N‐application rate of 264–272 kg N ha −1 in eastern China. Maximum grain yield (10.5 t ha −1 ) was obtained when 264 kg N ha −1 was applied. The recovery efficiency of N fertilizer was higher for NFOA and NNI (51–57%) than fixed‐time application of 270 kg N ha −1 (48%). The comparable high net profit (>$1080 ha −1 ) was achieved with lower N‐adjustment fertilizer input in 270 and 360 kg N ha −1 treatments. SPAD‐based NFOA and NNI methods are practical approaches for reducing excessive use of N fertilizer, achieving slight increase in yield, and net profit was decreased (360 kg N ha −1 ). More refinements are necessary to ensure that these strategies can be used for yield‐ and income‐enhancing production for farmers.