The yield of clover in 1910 was 8590 pounds an acre on the land fertilized for turnips, but only 1949 on the unfertilized land.
"The Farm That Won't Wear Out"
Cyril G. Hopkins
Where lime had been applied, the unfertilized land yielded 3852 pounds per acre, the fertilized, 4085 pounds, and the manured, 4976 pounds.
"Crops and Methods for Soil Improvement"
Alva Agee
If it remained attached to the anther, it would not be touched by the bee, and the flower would remain unfertilized.
"Wild Flowers Worth Knowing"
Neltje Blanchan et al