A Cardinal number represents an equivalence class of sets between which there is a bijection (one-to-one correspondence). It is the number of elements in any member of the equivalence class. An Ordinal number represents an equivalence class of well-ordered sets between which there is an order-preserving bijection. It is the number of elements in any member of the equivalence class. The difference is only in whether the sets are ordered.
It is the basis for protein manufacture in plants and plays a major part in photosynthesis. For lawns, shrubs and leafy houseplants, a nitrogen-rich fertilizer is the best choice. When reading a fertilizer package, nitrogen will be the first in a series of numbers appearing with dashes between them. For example, a formula of 10-0-0 is a nitrogen-only fertilizer.
Seed germinates best when it is either drilled or buried to a depth of about three quarters of an inch. While not quite as much of a fertilizer user as corn, sorghum does like its nitrogen. Without the aid of a soil test, fertilize at planting time with 300 pounds of 19-19-19 per acre.