402 BOTANICAL GAZETTE [MAY 
material in order to prevent the decomposition of organic nitrogen 
compounds—proteins, chlorophyll, phospholipines, etc. A similar 
situation may hold in alfalfa for sulphate as a sulphur source. 
On the basis of Wotrr’s old ash analyses of crop materials, 
agricultural scientists came to assume that so little sulphur was 
used by crops that there was no doubt that all soils furnished an 
abundance of this material. The magnitude of error likely to 
appear in the ashing method is well illustrated by the fact that 
Wo trr’s analyses showed that one hundred bushels of corn contain 
0.2 lb. of sulphur, while analyses of the modern fusion methods 
show at least 8.5 lb. or 42.5 times as much (2). Ashing seems to 
drive practically all of the organic sulphur off into the air, and 
determines only the small amount of sulphur existing in the 
inorganic form. 
The use of the fusion method (7) of determining the sulphur 
content of crops has quite changed the situation by showing that 
all crops are considerable users of sulphur, and some crops very 
heavy consumers of sulphur. This fact, together with the general 
low percentage of sulphur in soils and the large losses of sulphur 
from soils by leaching, has shown that the question of sulphur 
supply to crops needs serious consideration. The Oregon (11) and 
Washington (9, 14) stations have shown beyond doubt that alfalfa 
cannot be grown successfully on many lands of those states without 
the addition of a sulphur source. They commonly get increased 
tonnage amounting from 100 to 500 per cent by the use of gypsum 
or other sulphur sources. The protein content of the hay is also 
increased almost 2 per cent in some cases by the use of sulphur 
fertilizers. From these facts it seems probable that the marked 
benefits received from the use of land plaster on legumes and other 
high sulphur-using crops in eastern United States and England 
during the last 150 years are due to gypsum furnishing an excellent 
sulphur source (3). 
ART and PETERSON (5) of Wisconsin, BRowN and KELLOGG 
(2) of Iowa, and SHEpp (12) of Kentucky have all emphasized the 
fact that a permanent fertility system must look after the sulphur 
supply of the soil as well as the so-called three fertilizer elements— 
nitrogen, potash, and phosphorus. Recent work is indicating that 
