질소분시가 청예피의 생육특성 , 수량 및 조성분 함량에 미치는 영향 = Effects of Split Nitrogen Application on Agronomic Characteristics , Forage Yield , and Chemical Composition of

다국어 초록 (Multilingual Abstract)

This study was conducted at a volcanic ash soil of Jeju island in 1999 to determine the optimum frequency of split N application for forage production of Japanese millet [Echinochloa crusgalli var. frumentacea (Roxb.) W. F. Wight]. Nitrogen fertilizer was applied with 200 ㎏ N/㏊, and frequencies of the split applications were 1, 2, 3, 4 and 5 times. A Jeju native cultivar of Japanese millet was planted at a rate of 30 ㎏ seed/㏊ on 31 May, and harvested on 6 September. Days to heading increased from 84 to 88 days as N was split-applied from one to five applications. Plant height increased from 152 to 188 cm as N was split-applied from one to three applications and then decreased to 156 cm in five applications. This pattern held for leaf length, leaf width, and stem diameter which were greatest in three applications with 42.4, 2.6, and 0.67 ㎝, respectively. Green leaf number was 10 regardless of the treatments. Dry matter (DM) yield increased from 6.96 to 11.99 MT/㏊, crude protein (CP) yield from 0.47 to 0.89 MT/ha, and total digestible nutrients (TDN) yield from 3.80 to 6.81 MT/㏊ as N was split-applied from one to three applications, and then decreased to 7.51, 0.63 and 4.43 MT/ha, respectively, in five split applications. Nitrogen uptake increased from 75.1 to 142.9 ㎏/㏊ as N was split-applied from one to three applications and then decreased to 101.3 ㎏/㏊ in five split applications. Nitrogen use efficiency decreased from 92.8 to 74.1 ㎏ DM/㎏ N with increasing split N application. Crude protein content increased from 6.7 to 8.4%, ether extract content from 5.7 to 6.1%, nitrogen free extract content from 30.7 to 34.7%, and TDN content from 48.0 to 53.0%, but crude ash content decreased from 10.2 to 8.0% and crude fiber from 38.9 to 35.5% as N was split-applied from one to five applications. These results indicate that the optimum frequency of split N applications is three times for forage production of Japanese millet in volcanic ash soils of Jeju island.