Differential effects of sole and phosphorus based nitrogen fertilizer sources on wheat growth and nutrient use...

Management of nutrients under changing climatic conditions has become a major challenge in agriculture, affecting nutrient availability, plant uptake, and overall crop productivity. Optimizing fertilization strategies, particularly through balanced fertilizer applications, is crucial to enhancing nutrient use efficiency and ensuring sustainable crop yields under these dynamic environmental conditions. This study contributes to improving nitrogen management strategies for wheat in calcareous soils by evaluating different nitrate and ammonium ratios, offering insights for enhancing nitrogen use efficiency and yield optimization. The treatments included: T₁ = DAP-Urea (100% N as NH₄⁺), T₂ = DAP-CAN (29% N as NH₄⁺ and 71% N as NO₃^-), T₃ = NP-Urea (32% N as NH₄⁺ and 68% N as NO₃^-), and T₄ = NP-CAN (100% N as NO₃^-). Results showed that N uptake varied with NH₄⁺/NO₃^- ratios in the fertilizer combinations. Wheat supplied with 100% N as NO₃^- (NP-CAN) had higher N, P, and K use efficiencies compared to plants with 100% N as NH₄⁺ (DAP-Urea). Plants with 100% N as NO₃^- had higher INR, NACE, NARE, and NAUE (77%, 43%, 83%, 24 kg kg^- 1) compared to those with 100% N as NH₄⁺ (67%, 26%, 29%, 18 kg kg^- 1). FUTE decreased to 33% (NP-CAN) from 40% (DAP-Urea), while NPUE dropped to 29 g g^- 1 (NP-CAN) from 67 g g^- 1 (DAP-Urea). The fertilizer stress factor increased from 60% (DAP-Urea) to 67% (NP-CAN). Similar trends were observed in P and K use efficiency. Plants with higher agronomic parameters and grain yield per hectare also showed improvements in PUE and KUE. Economic analysis indicated that nitrate-based NP combinations generated 13-42% more net income and 3-12% higher BCR compared to DAP-Urea. The VCR (3.13 to 5.04) suggests that nitrate-based combinations are economically viable for farmers.