In 1907 the Iowa Experiment Station issued a bulletin on the Vitality, Adulteration and Impurities of Clover, Alfalfa and Timothy Seed for Sale in Iowa in 1906. In that bulletin attention was called to the impurities that were commonly found in the above seeds. It was shown that the average impurities of 130 samples was 1.93%; the average impurity of five poor samples was 10.3%; the average impurity of five good samples for 0.96%. The vitality in some cases was very low; four samples showed a vitality of 99% and over; and a considerable number below 80%. Much the same things were found to exist in the case of the white clover, alsike, alfalfa and timothy seed.
Pammel, L. H. and King, Charlotte M.
"Results of seed investigations for 1907.,"
Bulletin: Vol. 9
, Article 1.
Available at: https://lib.dr.iastate.edu/bulletin/vol9/iss99/1