Influence of ash on the fiber composition of dried dairy manures

The objective of this work was to examine the role of ash in the compositional analysis of dried dairy manures. Ninety-nine dairy manures obtained from Connecticut, Maryland, New York, Pennsylvania and Virginia were dried at 60 °C, and ground to 20 mesh. Samples were analyzed for neutral and acid detergent fiber, acid detergent lignin, total carbon, total nitrogen, and ash. In addition, cellulose and hemicellulose were computed by difference. Results indicated that high ash contents (8–52% of dry matter) can dramatically and unpredictably alter various measures of fiber composition and are a significant source of error in the determination of manure composition and how it relates to mineralization or other compositional influenced factors. Also, while the ash content of the dried intact manure can easily be determined, it is difficult to estimate the ash contribution to the individual fiber determinations, especially if sequential assays are performed.