Does the Organ-Based N Dilution Curve Improve the Predictions of N Status in Winter Wheat?

Ke Zhang, Xue Wang, Xiaoling Wang, Syed Tahir Ata-Ul-Karim, Yongchao Tian, Yan Zhu, Weixing Cao and Xiaojun Liu
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Ke Zhang: National Engineering and Technology Center for Information Agriculture, Nanjing Agricultural University, Nanjing 210095, China
Xue Wang: National Engineering and Technology Center for Information Agriculture, Nanjing Agricultural University, Nanjing 210095, China
Xiaoling Wang: National Engineering and Technology Center for Information Agriculture, Nanjing Agricultural University, Nanjing 210095, China
Syed Tahir Ata-Ul-Karim: Institute for Sustainable Agro-ecosystem Services, The University of Tokyo. Department of Global Agricultural Studies, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8654, Japan
Yongchao Tian: National Engineering and Technology Center for Information Agriculture, Nanjing Agricultural University, Nanjing 210095, China
Yan Zhu: National Engineering and Technology Center for Information Agriculture, Nanjing Agricultural University, Nanjing 210095, China
Weixing Cao: National Engineering and Technology Center for Information Agriculture, Nanjing Agricultural University, Nanjing 210095, China
Xiaojun Liu: National Engineering and Technology Center for Information Agriculture, Nanjing Agricultural University, Nanjing 210095, China

Agriculture, 2020, vol. 10, issue 11, 1-19

Abstract: Accurately summarizing Nitrogen (N) content as a prelude to optimal N fertilizer application is complicated during the vegetative growth period of all the crop species studied. The critical nitrogen (N) concentration (Nc) dilution curve is a stable diagnostic indicator, which performs plant critical N concentration trends as crop grows. This study developed efficient technologies for different organ-based (plant dry matters (PDM), leaf DM (LDM), stem DM (SDM), and leaf area index (LAI)) estimation of Nc curves to enrich the practical applications of precision N management strategies. Four winter wheat cultivars were planted with 10 different N treatments in Jiangsu province of eastern China. Results showed the SDM-based curve had a better performance than the PDM-based curve in N nutrition index (NNI) estimation, accumulated N deficit (AND) calculation, and N requirement (NR) determination. The regression coefficients ‘a’ and ‘b’ varied among the four critical N dilution models: Nc = 3.61 × LDM –0.19 , R 2 = 0.77; Nc = 2.50 × SDM –0.44 , R 2 = 0.89; Nc = 4.16 × PDM –0.41 , R 2 = 0.87; and Nc = 3.82 × LAI –0.36 , R 2 = 0.81. In later growth periods, the SDM-based curve was found to be a feasible indicator for calculating NNI, AND, and NR, relative to curves based on the other indicators. Meanwhile, the lower LAI-based curve coefficient variation values stated that leaf-related indicators were also a good choice for developing the N curve with high efficiency as compared to other biomass-based approaches. The SDM-based curve was the more reliable predictor of relative yield because of its low relative root mean square error in most of the growth stages. The curves developed in this study will provide diverse choices of indicators for establishing an integrated procedure of diagnosing wheat N status, and improving the accuracy and efficiency of wheat N fertilizer management.

Keywords: critical nitrogen dilution curve; leaf area index; N diagnosis; dry matters; grain yield (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2020
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