In agriculture, crop yield (also known as "agricultural output") is not only a measure of the yield of cereal per unit area of land under cultivation, it is also the seed generation of the plant itself, i.e. one grain of wheat produces a stalk yielding three grain, or 1:3. The figure, 1:3 is considered by agronomists as the minimum required to substain human life: one of the three seeds must be set aside for the next planting season, the remaining two either consumed by the grower, or one for human consumption and the other for livestock feed. And so the process repeated itself.