Key Crop Parameters for Almanac Modeling of High Biomass Energy Sorghum Growth and Productivity.

Sorghum [Sorghum bicolor (L.) Moench] grown as a high biomass energy crop is an excellent candidate feedstock crop for the cellulosic ethanol industry because of its robust establishment, broad adaptability, drought tolerance, water and nutrient use efficiency, and high annual biomass yields. Despite these many advantages, large-scale commercial production still faces many challenges, among which is the lack of information on spatial and temporal feedstock yield variability. This information is needed to provide the bioenergy industry with realistic estimates of available feedstocks so they can account for regional production risks. Regional and site-specific differences in climate, soil type, topography, and management practices can result in significant variations in feedstock yields and quality. While field studies are valuable and necessary, they are however quite costly. Process-based crop simulation models, such as ALMANAC can serve as effective tools with capabilities to simulate various ‘what if’ scenarios related to the production of bioenergy feedstocks. In this study, which is part of a joint ONR/USDA project plan for a resource assessment of feedstock supply to produce advanced biofuels in Hawaii and the southeastern USA, good progress has already been made to compile key crop parameters for four high biomass energy sorghum varieties. These parameters, along with the appropriate weather, soil, and management practices databases can be used to apply the ALMANAC model to evaluate the growth and long-term productivity of high biomass energy sorghum across various landscapes in Hawaii, the Pacific basin and the southeastern USA. The key crop parameters include: radiation-use efficiency (RUE), leaf area index (LAI), light extinction coefficient (K_c), maximum crop height and rooting depth, optimum plant density, N,P&K uptake etc., Besides the ALMANAC model, gathered crop parameters will also be compatible for use with other simulation models such as EPIC/APEX, SWAT and DSSAT.