Energycane Harvest Date Effects On Biomass, Sugar, and Fiber Yields.

Reliable and high yielding biomass is a prerequisite to a viable bioenergy industry. Energycane, a sugarcane variety grown solely as a biomass feedstock, is an excellent candidate for the Southeastern U.S. The most recent commercial released energycane is ‘Ho 02-113.’ Our objective was to determine the yield and biomass characteristics of Ho 02-113 harvested across an 8 month time span from August thru March. Stalks of Ho 02-113 were hand cut from two tests near Houma, LA, each month and analyzed for biomass, brix (total suspended solids in juice), theoretically recoverable sucrose (TRS), and fiber mass. Yield was estimated using a stalk population of 252,000 ha^-1.  Biomass peaked at 155 Mg ha^-1 in December 2012, and was lowest in August (118 Mg ha^-1). The average across the 8 month harvest period was 132 Mg ha^-1. Brix, a measure of total sugar content, was lowest in August (7.0 %) and increased each month until it reach a high of about 11% in November that lasted through March. TRS also was lowest in August (22 g sucrose kg^-1 cane), indicative of immature stalks. TRS increased each month and peaked in February at 49 g kg^-1. However, TRS was very low when compared to 2012 Louisiana commercial sugarcane average of 114 g kg^-1. Fiber peaked in December-January at 360 g kg^-1. This would equal 56 Mg dry biomass ha^-1. Calorimeter tests revealed the energy content of the fiber to be 16.7 Gj Mg^-1. Energycane yield, brix, TRS, and fiber varied throughout the harvest season and were not always reflective of each other.  The biomass processing strategy will determine the optimal harvest time for energycane; early fall (lower biomass, lower sugars), late fall (high biomass but more sugars), winter (highest biomass, highest fiber), or early spring (high biomass, higher sucrose).