2013 Annual Report
Progress has been made to gather key ALMANAC model parameterization data for the evaluation of candidate high biomass energy crops; sugarcane, energy cane, energy sorghum, and banagrass; (1) Crop parameters - the basic plant growth processes that need to be parameterized to simulate bioenergy crop growth and yields. Model simulations of growth processes, such as leaf area index (LAI) over time, and dry matter accumulation, are currently being conducted to fine-tune the parameters and test the accuracy of model simulated vs. measured data; (2) Crop management - this includes information on land preparation, fertilizer application, planting, irrigation and harvesting. For sugarcane, historical crop management data for 8 fields over a 13-year period (1999-2012) will be used to further validate model performance; (3) Soils data – Currently, the ALMANAC model uses the USDA-NRCS Soil Survey Geographic (SSURGO) database for soil parameter inputs. Soil parameter data gathered by project co-operating partners (University of Hawaii at Manoa, Hawaii, and USDA, ARS, Parlier, California) has proved invaluable in correcting soil parameter errors in some specific test field sites; (4) Weather data - For more accurate model testing, field-specific weather data (18 stations) was obtained from HC&S and processed into ALMANAC compatible input formats.
Given the competition for the water resources in Hawaii, sustainable production of bioenergy feedstocks will be driven by management strategies that optimize water use efficiency, enhance feedstock yields, while minimizing environmental impacts. By working closely with project co-operators, we were able to obtain crucial model parameterization data for evaluating water use efficiency and potential bioenergy cropping systems’ impacts on ecosystems services; soil organic carbon by depth, greenhouse gas fluxes (CO2, N2O and CH4 and related soil moisture and temperature), pH, soil nutrient content, etc. Simulations to compare the productivity and global warming potentials (GWPs) of sugarcane (a crop with a high water-demand) and banagrass (a relatively drought tolerant bioenergy crop) at three irrigation levels; full irrigation-100%, 75% and 50% are being conducted. Set to begin in 2014, we will adapt and apply the generated technologies to the southern USA, a region which has the perfect agroclimate for optimizing bioenergy feedstock production.