Productivity, Fossil Fuel Replacement Potentiality and GHG Emission Reduction Ability from Lignocellulosic Bioenergy Crops Grown on Marginal Land.

The aim of this investigation was to study the production system of perennial and annual bioenergy crops on marginal lands. The perennial crops were napier grass (Pennisetum purpureum (L.) Schum.), and energy cane (Saccharum spp), while annuals were sorghum (Sorghum bicolor L. Moench) (biomass- ES5200, sweet-EJ7281). Three nitrogen fertilization rates (0, 100 and 200 kg N/ha) and two cover crops (no cover and clover) were used with the perennials while two nitrogen fertilization rates (0, 90 kg/ha) and four cover crops treatments (no cover, annual rye, vetch, and rye+vetch) were used with the annuals. Field experiments were conducted at the Agricultural Research Farm, Fort Valley, GA, from 2011-2015. The results showed napier grass produced higher biomass (30.4 Mg/ha) in comparison to energy cane (20.1 Mg/ha). Cover crop and different fertilizer rates did not show any significant difference in crop biomass production. In case of annuals, sweet sorghum produced significantly higher biomass. The dry matter yield of biomass sorghum ranged from 10.9 – 48.6 Mg/ha (Mean =30.8±10.9) while 9.9-51.7 Mg/ha (Mean=33.1±11.8) for sweet sorghum. No significant difference was observed in dry matter yield of biomass and sweet sorghum in response to nitrogen rates or cover crops treatments. The calculated calorific value for energy cane and napier grass was 34.5% and 35.8 % of commercial motor gasoline respectively. The net greenhouse gas (GHG) emission from combustion of bioethanol produced from biomass of one hectare of energy cane and napier grass was found to be lower (32% and 34% respectively) when compared to GHGs emitted from equivalent amount of motor gasoline combustion. We conclude that these lignocellulosic bioenergy crops can be highly suitable for producing lignocellulosic biomass on marginal lands with limited inputs and can put significant amount of unutilized farm resources to productive use.