Effects of rate, way and time of nitrogen application on growth and grain yield of maize (Zea mays L.)

The role of nitrogen (N) management practices in increasing grain yield of maize (Zea mays L) is not fully investigated in northern Sudan. Therefore, an experiment was conducted at Hudeiba Research Station Farm during 2003- 2005 growing seasons to study the effects of rate, way and time of N application on growth, grain yield and yield components of maize. Cultivar Hudeiba-l was used in this experiment. The results showed that neither rate, nor the way and time of application had significant effects on days to 50 % tasselling and silking, except for November sowing in 2003. Nitrogen rate significantly affected plant height and days to maturity in both sowings in 2003. Application of N as a split dose resulted in significant increases in plant height in November sowing in 2003, while the application of N at sowing significantly increased plant height in November and August sowings in 2003 and 2004, respectively. On the other hand, N rate, way and time of application did not significantly affect most of the yield components, except in few cases. Application of N as a split dose significantly increased number of kernels/ear in November sowing in 2004, while in contrast; it reduced the 100- kernel weight in August sowing in 2003. The results also, showed that in August and November sowings, addition of 43 kg N/ha increased maize grain yield by 28%, 2%, 24% and 43% in 2003 and 2004, respectively. However, further increases in N rate from 43 to 86 kg N/ha resulted in grain yield increases ranging from 5% to 11% and from 10% to 11% in both August and November sowings, respectively. Application of N as a whole dose significantly gave about 12% more grain yield than the split N application in August sowing in 2003, while the time of N application did not significantly affect maize grain yield in all four sowings. The interaction effects of N rate x way of application and also the way x time of application on grain yield were significant only in August sowing in 2003. Generally, August sowing in 2003 gave greater grain yield (2384 kg/ha) than that obtained from August sowing in 2004, while November sowing (5429 kg/ha) in 2003 gave higher grain yield than November sowing in 2004. Also, November sowing out yielded August sowing by 127% and 171% in 2003 and 2004, respectively. In conclusion, addition of 43 kg N/ha significantly increased maize grain yields in all four sowings, however, the increases varied with the season and year of planting