The Interaction of N Sources and Drought Stress at Flowering Stage of Maize on N and P Uptake and Efficiency

The effects of organic and inorganic N sources on nutrient (N and P) efficiency under the water-stressed conditions have not yet been determined. Thus، a field study was conducted to determine the influence of N from different sources along with drought stress on nutrient efficiencies of maize. Main plots consisted of two irrigation treatments (i. e.، optimum irrigation and cut-off irrigation at silking stage for two weeks)، and subplots comprised N fertilizers (cattle manure: 40. 8 Mg ha-1، poultry manure: 13. 3 Mg ha-1، urea fertilizer: 435 kg ha-1، cattle manure + urea fertilizer: 20. 4 Mg ha-1and 20. 4 Mg ha-1، respectively) and control (without fertilizer). Results indicated that the imposition of water deficit and fertilizer type had a significant effect on N uptake while P uptake was significantly affected only by fertilizer type. The highest N and P uptake were obtained with poultry manure. Similarly، significant differences in N and P use efficiency and N physiological efficiency were observed between the water deficit and fertilizer type (P