| Popis: |
Several potential fuelcrops have been studied individually, but relatively little work has been done to compare the various temperate species in side-by-side trials. In this study, we have examined the production of readily fermentable carbohydrates and biomass by six fuelcrop candidates: grain sorghum (Sorghum bicolor), Jerusalem artichoke (Helianthus tuberosus), maize (Zea mays), sugarbeet (Beta vulgaris), sweet potato (Ipomoea batatas) and sweet sorghum (Sorghum bicolor). A randomized complete block design with four replicates was employed at each of three locations that were somewhat diverse in soil type, elevation, growing season length, and 1980 rainfall distribution. Fermentables in the harvestable dry matter were determined colorimetrically following dilute acid plus enzymatic hydrolysis. Overall, sugarbeet was the most prolific producer of fermentables (7.4 Mg/ha); Jerusalem artichoke (5.8 Mg/ha), maize (4.8 Mg/ha) and sweet sorghum stems (5.8 Mg/ha) were statistically equivalent, while sweet potato (4.0 Mg/ha) and grain sorghum (3.8 Mg/ha) were less productive than the other candidates. The crops performed somewhat differently at each location, but the most striking site-specific differences were seen at the site with the coarset textured soil and driest season. At that location, maize produced the least fermentables (0.6 Mg/ha). Biomass production generally reflected either the amount of time each species was actively growing or limitations to growth associated with drought. We make no general recommendations concerning a preferred temperature fuelcrop. Based on our studies, however, maize may not always be the fuelcrop of choice; others, especially sugarbeet and sweet sorghum (when harvested for grain also), may be superior to maize in productivity of fermentable substrates. |
