University of Minnesota
University of Minnesota
College of Biological Sciences

Protocol for QA/QC for data related to biomass harvests

The most common data collected at Cedar Creek comes from the harvesting and weighing of plant samples. The goal of this protocol is to provide multiple checks throughout the data gathering process to minimize or eliminate incorrect data.

Field Quality Control:

As biomass is harvested from each plot into trays, each tray is labeled from plot number, tray number, and total number of trays/plot. These labels are then independently checked before trays are removed from plots. As trays are removed from plots, plots are records are taking verifying which plots have been collected and the number of trays/plot. This record is checked to verify that all plots have been harvested and collected.

Sorting Quality Control:

The arrival of each plot to the sorting room is recorded with a count of the trays for each plot. This record is compared to the field record to assure no trays have been misplaced. As plots are sorted, the species found in each plot are recorded. Completion of each plot’s sorting is recorded on a separate checklist to verify no plots have been missed. Before sorted biomass is placed into bags for drying, a supervisor confirms species have been indentified correctly.

Weighing Quality Control:

All species from a given plot are weighed consecutively before weighing begins for another plot. As each species is weighed, the weight is recorded on the sorting record sheet. All weights are also transferred directly from the scale into an Access database. As samples are weighed, their species identification is rechecked.

Data collection and verification timeline:

Biomass is dried for one week before weighing. Individual samples will be labeled identifying the day that drying began to ensure that weighing may begin as early as possible. Weighing is to be done immediately after drying is complete, and should take no longer than three days for most experiments. Each day, the information manager monitors the incoming data for systematic errors in data recording.

Upon completion of weighing, three QC procedures are implemented.

  1. Electronic records are compared to hand written records, and all discrepancies are recorded.
  2. The information manager graphs measured values for species in each plot against the average of the values of the last three harvests and records all outliers.
  3. The research manager visually compares measured values to the values from the last three years looking for and recording suspicious trends.

These procedures should take no more than 2 days. All possible errors detected through these procedures are examined through checking dried samples for correct weight and species ID and re-sampling from the field as necessary. This checking should take no more than two days.

Total time from beginning of harvest to finalized data for most experiments is approximately 15 days.