Nitrogen (N) fertilizer management is one of the important aspects of economic production of sorghums in sustainable agriculture. The aim of the study was to evaluate the effects of different N application rates and its split N application methods on productivity, growth characteristics, N accumulation, N use efficiency (NUE), and feed value of Sorghum × Sudangrass hybrids. Treatments consisted of five N application rates (0, 150, 200, 250, and 300 kg ha-1) and two split N application methods (40% in basal N, 30% at the growing stage, and 30% after the first harvest vs. 50% in basal N and 50% after the first harvest). Plant height, leaf width, and stem diameter were increased (p≤0.05) with increasing N fertility rates at each harvest. Chlorophyll content (expressed as SPAD values) was the highest at a rate of 300 kg N ha 1 (first harvest, 46.32; second harvest, 33.09). It was the lowest at zero N (first harvest, 21.56; second harvest, 18.5). Total N, N uptake, and NUE were increased with higher N rates. Split N application had little effect on total N, amount of N uptake, or NUE. Total dry matter yields were the highest (21,715 kg ha-1) at a rate of 300 kg N ha-1. It was the lowest (10,054 kg ha-1) at zero N. Our results suggest that more than 300 kg N ha-1 can improve dry matter yield to be above 116% compared to zero N, thus enhancing the agronomic characters of sorghums. However, no significant effect had been found for split N application. Further work is needed to determine the optimal N levels and the effect of split N application rates.

Ⅰ. INTRODUCTION
 Ⅱ. MATERIALS AND METHODS
  1. Experimental site
  2. Agronomic practices
  3. Experimental design
  4. Data collection
  5. Statistical data analysis
 Ⅲ. RESULT AND DISCUSSION
  1. Agronomic characteristics of plants
  2. SPAD values
  3. Evaluation of total N, N uptake and NUE
  4. Productivity of SSH
 Ⅳ. CONCLUSION
 Ⅴ. ACKNOWLEDGEMENT
 Ⅵ. REFERENCES

• Jeong Sung Jung(Gassland & Forage Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea) Corresponding author
• Young-Jin Kim(Gassland & Forage Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea)
• Won Ho Kim(Gassland & Forage Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea)
• Sang-Hoon Lee(Planning & Coordination Division, National Institute of Animal Science, Wanjugun, 1500, Republic of Korea)
• Hyung Soo Park(Gassland & Forage Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea)
• Ki Choon Choi(Gassland & Forage Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea)
• Ki-Won Lee(Gassland & Forage Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea)
• Tae-Young Hwang(Gassland & Forage Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea)
• Gi-Jun Choi(Gassland & Forage Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea)