EGU2020-4842, updated on 12 Jun 2020
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Wheat yield as influenced by urea applied with nitrification inhibitor and gibberellic acid

Rayehe Mirkhani, Mehdi Shorafa, and Mohammad Zaman
Rayehe Mirkhani et al.

Among the essential plant nutrients, nitrogen (N) is the most needed. Farmer apply N fertilizer, predominantly urea to meet crop N demand. However, a greater proportion of the applied urea-N is not being used by plants and lost to the atmosphere as ammonia or greenhouse gases. Therefore, it is necessary to enhance N use efficiency (NUE) of applied urea by minimizing such losses, which has environmental and economic implications. Nitrification inhibitor, such as nitrapyrin (NP), has the most potential to minimise N losses and enhance crop yield. Similarly, plant hormones, such as GA3, has the potential to reduce abiotic stress and improve plant growth and yield.   
A field experiment was established on an arable site at University of Tehran, Karaj to determine the effect of urea applied with Nitrapyrin and GA3 on wheat yield in 2018-2019. Karaj has a Mediterranean climate with annual precipitation of 265 mm. A randomized complete block design in five replications was used in this study. Treatments were: T1 (control treatment - without urea), T2 (farmers practice - 138 kg N/ha), and T3 (best practice - 138 kg N/ha+NP+GA3). Urea was applied in three split applications (46 kg N/ha) at growth stage (GS 21) or tillering, (GS 32) or stem elongation, and (GS 40) or booting. GA3 in T3 treatment, was applied only at stem elongation stage. 
The crop yield data showed that, urea applied with NP and GA3 had a significant (p ≤ 0.01) effect on grain yield, biological yield, number of grains, 1000-grain weight and % Harvest Index (%HI) compared to other treatments. Urea applied with NP and GA3 increased grain yield (10.30 t ha-1) by 13.9% and 46.1% compared to farmer practices (9.04 t ha-1) and control treatment (7.05 t ha-1). These results suggest that co-application of urea with NP and GA3 has the potential to enhance wheat yield in semi-arid area of Iran.

How to cite: Mirkhani, R., Shorafa, M., and Zaman, M.: Wheat yield as influenced by urea applied with nitrification inhibitor and gibberellic acid , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4842,, 2020


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  • CC1: Comment on EGU2020-4842, Giacomo Ferretti, 05 May 2020

    Dear Rayehe Mirkhani, 

    I would like to ask you some questions about your very interesting study. 

    Q1: I am very interested in the nitrification inhibitor you tested. I have some experience with DMPP, another nitrification inhibitor, and I know about DCD but honestly, I am not documented about nitrapyrin (NP). If my calculations are right, you have applied NP at approximatively 1.5% of the total N added in your field. Am I correct? If so, this dosage is quite similar to that used for DMPP also.


    Q2: Although you have not presented data about nitrogen dynamics in your abstract, do you have any clue about the efficiency of the nitrification inhibitor NP on the N cycle in your experiment? (for example N2O emission, NH4 and NO3 production/consumption etc…)


    Q3: Your experimental set-up includes 1) control (0 N input), 2) (farmer practice (138 kg-N urea) and 3) best practice (138 kg-N/ha + nitrification inhibitor NP and plant hormone G3).
    Is there a particular reason behind the choice of not including a treatment of urea+NP without plant hormone G3? I think this would have helped to better discriminate the effects on plant performances between NP and G3.


    Q4: For sure, as you also pointed out, adding nitrification inhibitor should grant lower N losses and thus higher NUE and advantages not only in environmental terms but also in economic perspective (higher yield). But it is also true that the cost of the fertilizer+NP (and G3) will be surely higher rather than the common urea. Do you already know how much is the cost increase of your best practice with respect to common practices? Is it affordable by farmers?

    Thank you very much. I am sorry we couldn't meet in the live chat!

    Best regards.