![Average (A) grain yield [t ha-1] and (B) grain protein concentration (%) for each treatment. The red line represents the amount of applied N fertilizer (secondary y-axis, Fig A).](https://www.researchgate.net/profile/Sara-Heshmati/publication/372251770/figure/fig1/AS:11431281173870222@1689070709273/Average-A-grain-yield-t-ha-1-and-B-grain-protein-concentration-for-each_Q320.jpg)
Content uploaded by Sara Heshmati
Author content
All content in this area was uploaded by Sara Heshmati on Jul 11, 2023
Content may be subject to copyright.
Content uploaded by Sara Heshmati
Author content
All content in this area was uploaded by Sara Heshmati on Jul 11, 2023
Content may be subject to copyright.
ECPA2023 – UNLEASHING THE POTENTIAL OF PRECISION AGRICULTURE - Book of Abstracts (Posters)
ECPA2023 14th European Conference on Precision Agriculture, 2-6 July 2023, Bologna, Italy 151
P74 - Site-specific nitrogen management in winter wheat
Heshmati, S1., Memic, E.1, Graeff-Hönninger, S1
Institute of crop production, Faculty of Agriculture, University of Hohenheim. Correspondence:
Sara.heshmati@uni-hohenheim.de
Introduction
An important factor in sustainable agriculture is the efficient use of fertilizer. It not only affects crop
productivity but also reduces environmental pollution [2]. Site-specific nitrogen (N) management
adjusts within-field N fertilizer rates aiming at optimizing grain yield, mitigating leaching problems,
and the emission of greenhouse gases [1]. In this study, we evaluated four strategies, including
sensor and crop model simulations, to calculate the optimum amount of wheat nitrogen demand on
a site-specific level.
Materials and methods
A field experiment was carried out during the vegetation period of winter wheat in 2021-2022 at the
Experimental Station Ihinger Hof (48◦44’ N, 8◦55’ E) of the University of Hohenheim in south
Germany. The average annual rainfall and annual temperature were 714 mm and 9.1 °C
respectively. The soil type of the experimental field was characterized as heavy calcareous brown
soil with high clay content. In October 2021, winter wheat (Triticum aestivum) was sown at a rate of
360 plants per m². The field was divided into 120 site-specific units (12 m × 48 m). The amount of
in-season plant N demand in each unit was evaluated based on different strategies: sensor-based
(ISARIA), crop growth model (DSSAT), a combination of sensor and crop growth model, and
common N fertilizer management practice by farmers (conventional method). N fertilizer was applied
as KAS (27 % N) at three different times (tillering BBCH 22-25, stem elongation BBCH 30-32, and
booting BBCH 44-49), with the amounts based on the prescriptions of each evaluated strategy. The
experiment followed a complete randomized block design with five replications (blocks). In each
block, the treatments were arranged in a row containing eight units, and the conventional method
was represented randomly per row. Data analysis was performed with SAS 9.4 statistical software,
using a Generalized Linear Mixed Model with Template Model Builder. Winter wheat grain yield and
grain protein concentration were modelled as a response to the fixed effects treatments, amount of
applied N fertilizer, and block. The row was included as random effects. Means were then compared
using the lsmean test at α = 0.05 significance level.
Results
Grain yield (p=0.85) and grain protein concentration (p=0.98) did not differ significantly between
the treatments (Fig. 1). Amount of applied N fertilizer neither significantly affected grain yield
(p=0.46) nor grain protein concentration (P=0.50). Slightly higher and lower grain yield and grain
protein concentration were found in plots that were fertilized based on the sensor + crop growth
model and the single DSSAT strategy, respectively.
ECPA2023 – UNLEASHING THE POTENTIAL OF PRECISION AGRICULTURE - Book of Abstracts (Posters)
ECPA2023 14th European Conference on Precision Agriculture, 2-6 July 2023, Bologna, Italy 152
Figure 1 Average (A) grain yield [t ha-1] and (B) grain protein concentration (%) for each treatment.
The red line represents the amount of applied N fertilizer (secondary y-axis, Fig A).
Discussion and conclusions
The results showed that site-specific fertilization could reduce total N application without yield loss,
which is in line with the findings of Argento et al. (2021) and Stamatiadis et al. (2018). The results
did not differ significantly between the strategies and different amounts of N fertilizer for grain yield
and grain protein concentration in 2022. The modelling strategy recommended the lowest amount of
N fertilizer without significant penalties for grain yield and grain protein concentration compared to
the other strategies. However, to decide on a suitable strategy for estimating in-season nitrogen
requirements of winter wheat on a site-specific level, an economic evaluation of these strategies
should be conducted based on current market grain and N fertilizer prices.
Acknowledgements
The 5G-PreCiSe project „5G-Umsetzungsförderung im Rahmen des 5G-Innovationsprogramms"
was funded by the Federal Ministry of digital and transport. Förderkennzeichen: 45FGU112_F.
References
1. Argento, F., Anken, T., Abt, F. et al. (2021) Site-specific nitrogen management in winter wheat supported
by low-altitude remote sensing and soil data. Precision Agric 22, 364–386.
https://doi.org/10.1007/s11119-020-09733-3
2. Flowers, M., Weisz, R., Heiniger, R., Osmond, D. and Crozier, C. (2004), In-Season Optimization and
Site-Specific Nitrogen Management for Soft Red Winter Wheat. Agron. J., 96: 124-134.
https://doi.org/10.2134/agronj2004.1240
3. Stamatiadis, S., Schepers, J. S., Evangelou, E., Tsadilas, C., Glampedakis, A., Glampedakis, M., et al.
(2018). Variable-rate nitrogen fertilization of winter wheat under high spatial resolution. Precision
Agriculture, 19(3), 570–587
