Fixed-time corrective dose fertilizer nitrogen management in wheat using atLeaf meter and leaf colour chart

Abstract

Fertilizer nitrogen (N) management in any region following standard general recommendations discount the fact that crop response to N varies between sites and seasons. To devise field-specific N management in wheat at jointing stage (Feekes 6 growth stage) using atLeaf meter and leaf colour chart (LCC), eight field experiments were conducted in three wheat seasons during 2017–2020 in the West Delta of Egypt. In the first two seasons, four experiments consisted of treatments with a range of fertilizer N application levels from 0 to 320 kg N ha−1. Monitoring atLeaf and LCC measurements at Feekes 6 growth stage in plots with different yield potentials allowed formulation of different criteria to apply field-specific and crop need-based fertilizer N doses. In the four experiments conducted in the third season in 2019/20, different field-specific N management strategies formulated in 2017/18 and 2018/19 wheat seasons were evaluated. In the atLeaf-based fertilizer N management experiment, prescriptive application of 40 kg N ha−1 at 10 days after seeding (DAS) and 60 kg N ha−1 at 30 DAS followed by application of an adjustable dose at Feekes 6 stage computed by multiplying the difference of atLeaf measurements of the test plot and the N-sufficient plot with 42.25 (as derived from the functional model developed in this study), resulted in grain yield similar or higher to that obtained by following the standard treatment. The LCC-based strategy to apply field-specific fertilizer N at Feekes 6 stage consisted of applying 150, 100 or 0 kg N ha−1 based on LCC shade equal to or less than 4, between 4 and 5 or equal to or more than 5, respectively. Both atLeaf- and LCC-based fertilizer N management strategies not only recorded the highest grain yield levels but also resulted in higher use efficiency with 57–60 kg N ha−1 in average less fertilizer use than the standard treatment.

In-Season Estimation of Wheat Response to Nitrogen Using Normalized Difference Vegetation Index

“…The fact that N uptake in wheat is relatively slow at early growth stages and accelerates to a maximum around Feekes 6 growth stage supports the findings of this study (Doerge et al, 1991;Shukla et al, 2004;Tian et al, 2018;Ali et al, 2020). Several studies have found that using moderate doses of fertilizer N at planting and Feekes 2, followed by an adjustable dose at Feekes 6, worked better than the general recommendation (Bijay-Singh et al, 2002;Varinderpal-Singh et al 2012;Ali et al, 2021). The findings of this study are also supported by the work of Bijay-Singh et al (2011 and Ali (2020), who found that applying an NDVI-guided dose of N at the Feekes 5-6 stage of wheat produced yields equivalent to the general recommendation while using less total fertilizer N. An N management program that employs this concept will allow growers to determine the likelihood of an N response at harvest, thereby increasing their profit.…”

“…It has been documented that applying fertilizer N more than the need of the crop results in substantial N losses and, as a consequence, low N use efficiency (Fageria & Baligar, 2005;Ladha et al, 2005;Bijay-Singh, 2018;Ali, 2020;Ali et al, 2021). The findings of the present study highlight the necessity for field-specific management strategies to synchronize fertilizer N supply with N demand by the crop.…”

“…The findings of the present study highlight the necessity for field-specific management strategies to synchronize fertilizer N supply with N demand by the crop. In the research carried out at the same location as the present study by Ali (2020) and Ali et al (2021), the NRE by following the general recommendation for wheat was in the range of 43-55%. The lower values in the first three seasons of the present study could be due to the application of total fertilizer N dose in two split doses preceding the Feekes 6 growth stage of wheat.…”

“…They found that until Feekes growth stage 7, the linear relationship between RI-harvest and RI-NDVI became stronger. Furthermore, several researchers have indicated that the Feekes 6 stage is the appropriate stage for deciding the amount of field-specific fertilizer N for wheat (Bijay-Singh et al, 2011;Varinderpal-Singh et al, 2017;Ali, 2020;Ali et al, 2021). The concept of utilizing canopy reflectance to assess plant response during vegetative growth holds great potentiality.…”

Developing a nitrogen fertilizer management model for wheat in calcareous soils using the critical nitrogen dilution curve

“…At 70 DAS, the requirements were 66.7, 50.5, 27.9, 22.9, 22.2, 15.5, and -16.6 kg N ha −1 , respectively. In general, wheat response to application of N fertilizer after Feekes 6 growth stage (around 55 DAS) is low (Bijay-Singh et al 2011;Ali 2020;Ali et al 2021), although the hypothetical N fertilizer requirement used at 70 DAS was only for comparison.…”