1922] WOODARD—SOIL FERTILITY IoLr 
phosphorus for 100 or more years of alfalfa. No. 34 has phosphorus 
enough to grow alfalfa 189 years, but sulphur enough for only 14 
years. The phosphorus content of no. 28 is sufficient to grow 
alfalfa for 131 years, but the same crop would deplete the sulphur 
in 11 years. All these soils have sufficient phosphorus to grow 
maximum yields of alfalfa for 20 years or longer, while all but two 
would be depleted of sulphur in less than 20 years. 
Of the other crops mentioned, corn, wheat, and clover remove 
smaller amounts of sulphur than phosphorus; while timothy, like 
alfalfa, removes more sulphur than phosphorus. Timothy, how- 
ever, removes only about one-fourth as much sulphur, and one- 
fourth as much phosphorus as alfalfa, so that the supply of each 
would last correspondingly longer, yet soil 9A is the only one that . 
carries sufficient sulphur for roo crops of timothy. Soil gA has 
sulphur enough to grow timothy 159 years, clover 139 years, corn 
232 years, and wheat 355 years. No. 34 has phosphorus enough 
for 401 corn crops, 568 wheat crops, and 341 clover crops; yet the 
sulphur would be depleted by 80 corn crops, 122 wheat crops, or 
48 clover crops. The lowest phosphorus content is in soil 1A, a 
sandy loam soil, which has 720 pounds of phosphorus in the surface 
7 inches of soil. The phosphorus in this soil would be depleted 
by growing corn 42 years, wheat 60 years, timothy 80 years, clover 
36 years, or alfalfa 20 years. In the same soil the sulphur would 
be removed by 40 years of corn, 62 of wheat, 28 of timothy, 24 of 
Clover, or 7 of alfalfa. 
Table II shows the importance of both sulphur and phosphorus 
if maximum crops of legumes, particularly alfalfa, are to be grown. 
It also shows that, in most soils, sulphur is more likely to be defi- 
cient than phosphorus. It does not take into account the leaching 
of these elements from the soil, which is practically nil in the case 
of phosphorus and very high in the case of sulphur; nor the supply 
in the rain water, which is nil in the case of phosphorus and may be 
quite high in the case of sulphur near cities in the humid regions. 
Whether the amount of sulphur lost in the drainage water exceeds 
that gained in the rain water is still unknown. It is certain that 
the amount of leaching will vary with the character of the soil, the 
rainfall, and the character of the plant growth. The amount of 
