Asian Journal of Soil Science and Plant Nutrition

Synthetic nitrogen fertilizers can contribute to environmental hazards. Moreover, their manufacturing is an energy-intensive process which causes greenhouse gas emissions, which can lead to climate change. Therefore, it should evaluate the possibility to use organic sources such as Azolla as a partial substitute for synthetic nitrogen fertilizers in cultivation, as this may reduce the cost of fertilizer inputs, and promote sustainable agriculture. So, a field trial was carried out in the Tag El-Ezz Experimental Farm (30°56' 12.88" E longitude and 31°31' 47.64" N latitude) during seasons of 2021/2022 and 2022/2023 to assess the additive of nitrogen recommended dose (NRD=178.6 kg N ha^-1) as combined treatments of urea (46.5%N) as mineral nitrogen source and Azolla (4.0 %N) as organic nitrogen source. Also, the exogenous application of zinc (zinc sulfate, 22.8% Zn) and copper (copper sulfate, 21.8 %Cu) was evaluated. The tested plant was wheat (Cv. Giza 171). The nitrogen treatments [T₁: 100% of NRD as urea (control),T₂:75% of NRD as urea+25% of NRD as Azolla,T₃:50% of NRD as urea+50% of NRD as Azolla, T₄: 25% of NRD as urea +75% of NRD as Azolla and T₅: 100% of NRD as Azolla] represented the main plots, while exogenous application of the studied elements [F₁: control (without spraying),F₂:Zn (at rate of 200 mgL^-1) and F₃: (Cu at rate of 20 mgL^-1)]  represented the sub main plots. The findings illustrate that wheat plants grown under T₂ treatment had  the highest values of growth performance (e.g., fresh and dry weights and total chlorophyll), yield and its components (e.g., grain yield, spike length and weight of 1000 grain) and biochemical traits (e.g., carbohydrates and total protein) compared to the corresponding wheat plants grown under other  studied N treatments, as T₁ treatment (control) came in the second order followed by T₃ treatment, while T₄ and T₅ treatments came in the last order, respectively. Regarding the external applications, the cu foliar application was the superior treatment followed by Zn treatment, while the control treatment came in the last order. Generally, the maximum values were recorded under combined treatment of (T₂xF₃). On the other hand, some soil fertility parameters like A-N, A-P and A-K were affected due to all studied treatments. Finally, it can be concluded the possibility of using Azolla as a partial substitute for synthetic nitrogen fertilizers. Also, the obtained results confirm the vital role of both Zn and Cu in wheat plants.