| Abstract: | Effect of Irrigation and Fertilizer Placement on the N-Uptake by Wheat under Semiarid Conditions of Karadj/Iran Field and greenhouse experiments were conducted under semiarid conditions of Karadj/Iran on a sandy to silty loam of alluvial soils (pH% 8,2) to study the effects of soil moisture regimes and N-fertilizer placement on yield, N-uptake and recovery of fertilizer N from 15NH4 15NO3, (15NH2)2CO and (15NH4)2SO4. There were two moisture regimes as main plots (W1 = Irrigation at 50% and W2 = Irrigation at 25% available water in 0–30 cm depth of soil), and two methods of fertilizer placement (broadcast and band application). Irrigation at (W1) increased the grain and straw yield 11 and 19% but not total N-uptake in the field experiment. (W1)-irrigation combined with band application resulted in the highest yield and total N-uptake. Utilization of applied N, however, was higher with (W2)-irrigation in both fertilizer placements. This result was confirmed by the data of the greenhouse experiment. Band application was superior to broadcast application for fertilizer N-uptake with both water managements. Ammonium sulfate showed the highest and urea the lowest difference between the two fertilizer placements. |
