86 BOTANICAL GAZETTE [FEBRUARY 
effects of gypsum can hardly be ascribed to its effect on the solu- 
bility of the potassium in the soil. It seems more likely that the 
soils that respond to the use of gypsum are deficient in some element 
that is supplied by the gypsum. 
Recent studies of methods for the analysis of organic material 
for sulphur have shown that all the sulphur is not recovered in 
the ash when organic material is burned. Hart and PETERSON 
(27, 28) found one hundred times as much SO, in the rice grain as 
in the ash of that grain, and forty times as much in the corn grain. 
Similar results were obtained with other grains, but the ratios were 
less in some cases. Onions, potatoes, crucifers, and legumes use 
large quantities of sulphur. Alfalfa removes twice as much sulphur 
as phosphorus from the soil. PETERSON (55) studied the sulphur 
compounds in plants and found proteins, volatile compounds, 
mustard oils, and sulphates. In ashing the plant material the 
sulphates remain, but at best part of the sulphur in other com- 
pounds is lost. Most soils are low in sulphur, which is present in 
the soil in the form of sulphates and organic matter. Sulphates 
are all soluble, and, like nitrates, they are not adsorbed to any 
great extent, and therefore are quickly leached out of the soil in 
the humid regions. The organic sulphur is insoluble but is readily 
oxidized to sulphates, so that it is gradually being lost unless taken 
up by the plant. Lyon and Bizze.t (44) in their lysimeter studies 
at Cornell found that the loss of sulphur in the drainage from 
uncropped lysimeters was as great as the loss in drainage and in 
the crops from cropped soil. The oxidation of organic sulphur to 
sulphates seemed to continue at the same rate in cropped and 
uncropped soil, and that not taken up by plants was lost in the 
drainage. . 
Cultivation stimulates oxidation and consequently the loss of 
sulphur. SwANSON and MILLER (68) report a loss of 38.53 per 
cent of sulphur from the surface and 41.56 per cent from the sub- 
soil of Kansas soils due to cropping. The surface soil of virgin 
land had 0.044 per cent sulphur, while adjoining cropped land had 
0.027 per cent. The sulphur content of the subsoil was 0.062 per 
cent in the virgin land and 0.036 per cent in the cropped land. 
On the other hand, phosphorus was practically the same in the 
