Biomass and Sugar Yield Response of Sweet Sorghum to Lime and Fertilizer¹

Abstract

Soil fertility requirements for sweet sorghum [Sorghum bicolor (L.) Moench] as an alcohol fuel crop have not been well defined. The primary objective of this study was to determine the biomass and sugar (% Brix ✕ extracted juice) yield response of sweet sorghum to N‐P‐K and lime. The study was conducted for 2 years on a Wynnville silt loam (fine‐loamy, siliceous, thermic Glossic Fragiudult) soil in the Cumberland Plateau region of northern Alabama. Experimental design was a split‐plot with 0 or 8 Mg ha−1 dolomitic limestone and combinations of 0, 45, 90, or 180 kg ha−1 N, 30 or 90 kg ha−1 P, and 40 or 120 kg ha−1 K. Liming significantly increased yields of fresh and dry biomass, grain, and juice sugar extracted from stalks. The lime also greatly reduced exchangeable soil Mn and Al and increased Mg and decreased Mn concentrations of the biomass. Due to the dominant effect of lime and other interactions, biomass and juice sugar yields were not consistently related to applied N, P, or K. In nonlimed soil, biomass and sugar yields decreased with high N in the presence of low P‐K, but not with high P or K. This suggests an acidity ✕ P and/or K interaction related to toxicity of soil Mn and/or Al. In the limed soil the maximum dry biomass and sugar yields occurred with 180‐90‐120 (1981) or 90‐90‐120 (1982) kg ha−1 N‐P‐K, however yields from some treatments with lower levels of N, P, or K were often not significantly different at the 0.05 level. Inherent soil acidity and related Mg deficiency must be corrected to obtain maximum response of sweet sorghum to fertilization in Wynnville and associated soils of the Cumberland Plateau region.

Juice, sugar, and bagasse response of sweet sorghum (Sorghum bicolor (L.) Moench cv. M81E) to N fertilization and soil type

“…Sugar content (Brix) varied between 10.7 and 18.9. Similarly, in Alabama, the Brix number of sweet sorghum juice ranged from 15 to 17 (Soileau & Bradford, ), whereas in India, Reddy et al . () obtained an average Brix number of 18.…”

Sugar Yield of Sweet Pearl Millet and Sweet Sorghum as Influenced by Harvest Dates and Delays Between Biomass Chopping and Pressing

“…A later harvest increased the extracted juice NSC yield by 130 % in sweet sorghum as compared to 64 % in sweet pearl millet (data not shown). In Kansas (USA), Wu et al [10] reported an average NSC yield of 4.4 Mg ha −1 from sweet sorghum juice, while Soileau and Bradford [27] reported NSC yield of 1 to 2.9 Mg ha −1 in Alabama (USA). In India, the juice NSC yield of 18 sweet sorghum genotypes was maximum 45 days after mid-flowering [28].…”

Optimizing Sweet Sorghum Production for Biofuel in the Southeastern USA Through Nitrogen Fertilization and Top Removal

“…Wortmann et al [30] reported dry stalk yields from 8 to 48 Mg ha −1 across a range of N fertilization rates, cultivars, and plant populations. Soileau and Bradford [25] measured dry biomass yields ranging from 6 to 18 Mg ha −1 across a range of fertilization and liming treatments. Miller and Ottman [16] reported no effect of irrigation frequencies on sweet sorghum dry matter yields, which ranged from 20 to 31 Mg ha −1 .…”