Determination of Energy Content of Crop and Cover Crop Biomass
Crop Production Systems Research Unit
2010 Annual Report
1a.Objectives (from AD-416)
Thermodynamically measure the energy content of crops, cover crops, and crop residue for potential carbon sequestration or utility as biofuels or soil amendments.
1b.Approach (from AD-416)
Cover crops and cash crops will be grown and plant residue harvested. The dried plant materials will be ground. Energy content of all plant materials will be determined in a bomb calorimeter. Energy content and carbon content production will be determined on a land area basis for potential use as biofuels or soil amendments to improve soil organic carbon content. Carbon sequestration potential of the various crops and cover crops will be calculated.
Wheat and rye were tested as potential rotation crops for cotton. The energy content of nineteen wheat and rye samples was analyzed by adiabatic bomb calorimetry. This instrument is the only device capable of measuring the heat of combustion (energy content) of biomass samples. The energy content is determined by burning a weighed sample in an oxygen atmosphere (25 atmospheres) enclosed in a stainless steel “bomb” under controlled conditions. The combustion is carried out in an isolated reservoir of water. The heat generated from the combustion of the sample is transferred to the water reservoir. The heat of combustion is computed from changes in the water temperature before, during, and after combustion, with proper allowance for thermochemical and heat transfer corrections. A standard, benzoic acid, is used to determine these corrections for the calorimeter. The thermodynamic conversion efficiency of each cover crop will be established.
Presentations on the results of our study are planned in 2011 at the Pittsburgh Analytical Chemistry Conference and the annual meeting of the Mississippi Academy of Sciences. The project was monitored through emails, telephone calls, and site visits.