← Back to Search
Nutrient Requirements And Use Efficiency By Sweet Sorghum
Published 1984 · Chemistry
Abstract Sweet sorghum ( Sorghum bicolor L.) offers potential as a renewable energy resource for production of ethanol. Nutrient requirements and nutrient use efficiency will influence the viability of sweet sorghum as a source of renewable energy, since fertilizer represents a significant non-renewable energy input. Biomass yields, and nitrogen (N) uptake by sweet sorghum were enhanced, while stalk carbohydrate levels were reduced, with the application of 112 kg N/ha. Application of 224 kg N/ha further increased N uptake by one cultivar, but did not further increase yields. Phosphorus application to a soil which contained a high level of available P had no effect on sweet sorghum. Uptake efficiency of applied N averaged 33% for two cultivars where 112 kg N/ha was applied. Since total N uptake was only slightly or not increased where 224 kg N/ha was applied, uptake efficiency of applied N at this rate fell to 17%. Theoretical ethanol yield increased with increasing N uptake. Nitrogen use efficiency defined as theoretical ethanol yield per unit of N taken up decreased with increasing total N uptake. Theoretical ethanol yields and N utilization by sweet sorghum compare favorably with grain crops when used as a feedstock to produce ethanol.