Potassium 320 pounds
Magnesium 68 pounds
Calcium 168 pounds
Phosphorus 77 pounds

If only the grain, including a yield of 4 bushels an acre of clover
seed, is considered, the straw, stalks and hay being returned to the
soil--either directly or in farm fertilizer--then the loss per acre
from four years of cropping as above would be as follows:

Potassium 51 pounds
Magnesium 16 pounds
Calcium 5 pounds
Phosphorus 42 pounds

The average annual loss by leaching from good soils in humid
sections is known by the results of many analyses to be about as
follows per acre:

Potassium 10 pounds
Calcium 300 pounds
Phosphorus 2 pounds

The average annual loss of magnesium in drainage water from good
soils is probably 30 pounds or more an acre, but the data thus far
secured are inconclusive with respect to that element.

A careful consideration of the trustworthy data clearly reveals the
fact that potassium is very abundant in normal soils, while
phosphorus is relatively very deficient; and, all things considered,