Monday, April 30, 2007

Chemical composition changes during outside storage of cereal straws

Qi (Keith) Luo, Forest Products, Alberta Research Council, 250 Karl Clark Rd, Edmonton, AB T6N 1E4, Canada, Shijie Liu, Faculty of Paper Science and Engineering, SUNY College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210-2778, and Kwesi Ampong-Nyarko, Crop Diversification Centre North, Alberta Agriculture, Food and Rural Development, 17507 Fort Rd, Edmonton, AB T5Y 6H3, Canada.

Storage systems are critical components of a sustainable biomass conversion industry. The annual nature of feedstock dictates the straw must be stored in the field for periods of up to a year. The detail chemical composition changes during the storage are not well investigated. Wheat straw, barley straw, and triticale straw harvested in Alberta, Canada, in October 2005. Twelve bales of the each straw were used for the study. The moisture content at the start of the storage was 16.2% for barley, 15.0% for wheat, and 16.2% for triticale. The mean bale weight was 415 kg for barley straw, 349 kg for wheat straw, and 483 kg for tritcale straw. Bales were left exposed to the weather but not in direct contact with soil. The straw was sampled at every two months interval for 12 months. Weathered sample was taken from the exterior of the bales which was exposed to the weather. Unweathered sample was taken from the interior of the bales which was not exposed to weather.

The purpose of this study was to determine how storage time affects the chemical composition. The results show that as storage time increases, cellulose content decreases and 1% NaOH solubility increases. The changes of hemicellulose, lignin, ash, silicates and silica, hot water extractives, and ethanol-benzene extractives of weathered and unweathered samples during the storage were also analyzed and discussed. The mass loss during the storage was estimated.