The effects of storage time on the extent and cause of grade reductions of farmers' stock Spanish peanuts harvested in the Southwest are discussed in this paper. This study was based on 184 randomly selected lots of farmers' stock peanuts sampled from 31 buying points throughout the Southwest area. Results of this research indicate that there was a significant decrease in the grade (sound mature kernels plus sound splits) with storage time and that this decrease occurred within the first 5 days of storage. The grade decreased from an initial average value of 71.3 to 70.3 after the 5-day storage period. There was a continuing decrease in grade with increased storage time; however, the change after the first 5 days of storage was not found to be significant. Decrease in grade results in an annual loss of approximately 2.26 million dollars in the Southwest peanut producing area.

The principal cause for this reduction was determined to be the shift of the weight ratio of hulls and kernels during storage while only a small part of the grade loss was due to kernel shrinkage. The method of drying and grading had a significant influence on the decrease in grade. Mechanically dried peanuts lost 1.8 percentage points in grade during a 90-day storage preiod compared to only 0.3 percentage points for field-dried peanuts.