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 Ukely 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 SO3 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- 

 IX)unds 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 Bizzell (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 adjoiniAg 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 



