Effect of different rates of phosphorus fertilizer on N-uptake, N-efficiency and zea mays yield

Effect of different rates of P fertilizer on N-uptake, N-efficiency and zea mays (C.V.LG 11) were studied by use of 15N technique. The main objectives of this study were to study effect of different level of P on N-utilization and determine the interaction between P and N on zea mays yield, and the efficiency of N-fertilizer during different stages of plant growth. The field experiment was conducted for two years 1985 and 1986. The treatments were 0, 80, 160 Kg N, as urea Co(15NH2)2 and 0, 40, 80, 160 Kg P2O5 as triplsuperphophate. The experiment design was randomized block of four replicates for each treatment. Yield (grain and drymatter), utilization of urea, N-uptake, total N, N-yield, Ndff%, Ndfs% and A-values were determined. All results indicate that zea mays responds to the addition of nitrogen and the yield increases with the increase of added nitrogen. The highest yield was for N2 (160 Kg) level during two seasons. Also zea mays responds clearly to phosphorus especially at stages 1 and 2, where dry matter yield increases with the increase of phosphorus rate. The highest yield was for P3 (160 Kg) rate. While in grain stage the response was for rate P1 (40 Kg) and P2 (80 Kg) in comparison with control. However P1, rate was dominant over P2 and P3. The effect of P2 rate on grain yield was very little in comparison with P1, while P3 decreases the grain yield during two seasons in comparison with control. There is an effect of N and P when added both or separately. There is also effect for interaction between them on the yield (grain and dry matter). Grenerally, from the previous data we can conclude that the rate 160 Kg N/ha and 40 Kg P2O5/ha were optimum rate for zea mays fertilization in Deir-Ezzor (Syria) and similar areas for grain yield. (author). 17 refs., 32 tabs