Submitted to: Washington State University College of Agriculture and Home Economics
Publication Type: Abstract only
Publication Acceptance Date: 4/27/2009
Publication Date: 6/1/2009
Citation: Stubbs, T.L., Kennedy, A.C. 2009. Composition of Cereal Crop Residue in Dryland Cropping Systems. Washington State University College of Agriculture and Home Economics. Interpretive Summary:
Technical Abstract: Cereal crops and cultivars vary in their composition, and also in their decomposition and contribution to soil organic matter. Large quantities of cereal crop residue that decompose slowly present an obstacle to the adoption of minimum till or no-till seeding, conversely lower quantities of crop residue that decompose more rapidly may leave the soil vulnerable to erosion by wind and water. Decomposition of cereal crop residues is associated with fiber and nutrient content, and growers have observed differences in decomposition among cultivars; however, little information exists on their residue characteristics. Cultivars of spring barley, spring wheat, and winter wheat grown at four locations in eastern Washington over two crop years were analyzed for neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), C, and N contents, and this information related to straw hemicellulose, cellulose and lignin content. Acid detergent lignin was highest in spring barley (9.9%), and least in winter wheat (9.2%) and hard white spring wheat (9.5%). Fiber components and nutrient content varied by location, precipitation zone, and cultivar. Residue in the drier year of the study had lower NDF, ADF, ADL, C, and C:N ratio. Foot-rot (Fusarium spp.) resistant winter wheat cultivars had higher NDF, ADF, and ADL than susceptible cultivars. The analysis used to determine fiber content of straw is expensive and labor intensive. We are developing near-infrared spectroscopy (NIRS) as a rapid, non-destructive, chemical-free method to predict residue fiber and nutrient content. Future research will also include residue tannin analysis to help predict straw decomposition. Fiber and nutrient characteristics of residue from wheat and barley cultivars currently produced in the Pacific Northwest can be used to predict residue decomposition in cropping systems that conserve soil and water, and enhance build-up of soil organic matter.