1A-05

The Effect of Additions on the Ensiling and Microbial Community of Senescent Wheat Straw

Joni M. Barnes, Tracy P. Houghton and David N. Thompson*

Biotechnology Department

Idaho National Engineering and Environmental Laboratory

P.O. Box 1625

Idaho Falls, ID  83415-2203

Phone: (208) 526-3977

Fax: (208) 526-0828

Email:  thomdn@inel.gov

Senescent crop residues collected during or after grain harvest are available once per year and must be stored for extended periods.  High moisture and microbial loads lead to spoilage during storage and risk of spontaneous ignition.  Ensiling is a wet method that could be used to store these residues.  To economically adapt ensiling to senescent biomass, methods to minimize the cost to build and operate such systems at a variety of scales, and the need for nutrient, moisture, and microbial additions must be determined.

Wheat straw ensiling tests inoculated with Lactobacillus plantarum were performed in sealed columns for 82 days to assess nitrogen, free sugar (as molasses), and moisture requirements. Oxygen was consumed within one month.  Without nitrogen or molasses additions, pH increased from 6.0 to 9.0, and dry matter and polysaccharide losses were 20 and 35%.  Final pH decreased as molasses increased, and increased as nitrogen increased. A final pH of 4.0 was attained in limited cases at ≥ 80% moisture.  Polysaccharide losses decreased linearly with final pH, varying from about 35% at pH 9.0 to about 5% at pH 4.0.  These data indicate polysaccharide stability likely depends on rapid transient and long-term maintenance of low pH.