Nitrogen response of sweet sorghum genotypes during rainy season

Sweet sorghum (Sorghum bicolor (L.) Moench) is a smart biofuel crop, which can be grown under tropical rainfed conditions without sacrificing food and fodder security. Three sweet sorghum cultivars (viz. ICSA 52 SPV 1411, CSH 22 SS and ICSV 93046) were grown under six nitrogen levels (0, 30, 60, 90, 120, 150 kg ha–1) on Vertisols during two rainy (kharif) seasons at ICRISAT, Patancheru, India. The results from two-year trial indicated that out of three sweet sorghum cultivars evaluated, sweet sorghum hybrid CSH 22 SS produced highest green stalk (46.90 t ha–1) and ethanol yield (1940 l ha–1) compared to other cultivars. The three cultivars responded well to applied N doses up to 150 kg ha–1, however, application of N beyond 90 kg ha–1 did not result in any significant increase in grain yield and economic returns. Net economic returns of Rs 32,898 ha–1 (US$ 601.21 ha–1) were significantly higher with 90 kg N ha–1 application as compared to other levels of fertilization. It is concluded that for obtaining the highest green stalk yield, ethanol yield and thereby maximum economic returns, sweet sorghum cultivar, viz. CSH 22 SS should be fertilized with 90 kg N ha–1