Sorghum (Sorghum bicolor (L.) Moench) is a potential crop for food, feed and bioethanol production. Ecologically sorghum can grow in different wide ranges of soil.  Unlike corn, sorghum could be ratooned. Field experiment was conducted to study the response of different cultivars of sorghum ratoon-1 to dosages of N fertilization applied on first-planted sorghum plants. The experiment was done in Way lima, Pesawaran of Lampung Province, Indonesia, in 2020.  Treatments were arranged factorially in randomized block design with three replications.  The first factor was sorghum genotypes including Super-1, Super-2, P/I WHP, GH-1, GH-6, Talaga Bodas, UPCA, and Numbu, while the second factor was N fertilization levels consisting of 0, 75, 150, 225 and 300 kg urea/ha. Sorghum was planted with row spacing of 80x20 cm. Fertilizers used were urea, SP-36, KCl, and cattle manure.  The fertilizers were applied on first-planted sorghum plants, so the ratoon-1 of sorghum plants were not fertilized at all.  The result of the experiment indicated that sorghum genotypes differently responded to N fertilization. The highest grain yield was found at Talaga Bodas, that is, 32.76 g/panicle, while the lowest grain yield was 23,96 g/panicle, found at GH-6 genotype.  The difference of sorghum grain yield was most due likely to different size and number of sorghum grain. On the other side, different levels of N fertilization did not show significant difference of sorghum ratoon-1.

Keywords: fertilization, nitrogen (N), ratoon,  sorghum, yield