Effects of Nitrogen Application on Sweet Sorghum (Sorghum bicolor (L.) Moench) in the Semi-Arid Tropical Zone of India

Sweet sorghum is a multipurpose crop that has great potential as a bioethanol crop. To make an appreciableprofit from cultivating sweet sorghum in the semi-arid tropics (SAT), such agronomic practicesas nutrient management need to be standardized. The objective of this study is to determine optimumnitrogen (N) rates for maximizing the grain and sugar yields of sweet sorghum during the rainy seasonin the Indian SAT. During the 2009 and 2010 seasons, the response of sweet sorghum being grownin an Alfisol to the application of six N rates (0, 30, 60, 90, 120, and 150 kg N ha-1) was evaluated inPatancheru, Andhra Pradesh, India. The chlorophyll content (SPAD reading), cane fresh weight, andgrain dry weight increased significantly in line with higher N rates. The volume of juice also increasedsignificantly, although sugar content (brix reading) did not change in line with higher N rates, consequentlyresulting in a significant increase in sugar yield as computed from the volume of juice and sugarcontent. There were smaller differences due to N application during the season when soil fertility wasat a medium level under high air temperature. Net income, as estimated from cane fresh weight andgrain dry weight, increased at rates up to 90 kg N ha-1, and higher N rates did not significantly affectproductivity or income, but instead caused severe lodging in 150 kg N ha-1 at the harvest stage. Basedon these results, an input of 90-120 kg N ha-1 could be recommended for maximizing sweet sorghumproductivity and farmers? income in the SAT region of India

H Uchino et al., 'Effects of Nitrogen Application on Sweet Sorghum (Sorghum bicolor (L.) Moench) in the Semi-Arid Tropical Zone of India', JARQ - Japan Agricultural Research Quarterly, vol. 47(1), pp.65-73, Japan International Research Center for Agricultural Sciences, 2013