246 



Journal of Agricultural Research 



Vol. V. No. 6 



the variety planted. Unlike the barley, this grain crop showed decided 

 differences in development upon the different rations during its growth, 

 as shown in Plate XXII, figure 3. In Table VIII are given the average 

 yields of the thrashed crop in the usual manner, the husks being care- 

 fully removed from the seed. 



Table VIII. — Average weights {in grams) of the air-dried oat crop 



Relative 



yields 

 when con- 

 trol= 100. 



Relative 



yields 

 when con- 

 trol=ioo. 



1 . Control 



2. Complete fertilizer 



3. Complete fertilizer +sodium sulphate . 



4. Complete fertilizer+calciura sulphate 



5. Sodium sulphate only 



6. Calcium sulphate only 



7. Sulphur only 



28. 5 

 56. o 

 57-5 

 54-5 

 19-5 

 19.0 



23-5 



100 



197 



100 

 200 



340 

 340 



The statements previously applied to the limited amount of data on 

 barley also apply to the oats. So far as the preceding table is concerned, 

 however, it indicates, as in the case of barley, no appreciable effect of 

 sulphates upon the development of straw when they supplement the 

 usual complete-fertilizer ration. Sulphur and sulphates alone even 

 depressed the yield of straw as compared with the control crops. 



In the case of the grain, the application of sulphur and sulphates alone 

 did not increase the yield as compared with the controls, although it 

 increased the ratio of grain to straw. The crops receiving complete 

 fertilizer indicate a marked stimulating effect of sulphates upon seed 

 production in this crop. Those crops receiving sulphates in addition to 

 a complete fertilizer produced 70 per cent more seed than those receiving 

 complete fertilizer only. 



The data from these two crops of the Gramineae family have shown 

 a marked response of these plants to the application of sulphates by 

 increased seed production. From these records it appears that under 

 present common methods of fertiUzation these grain crops may fre- 

 quently reach a maximum production of straw, but that the capacity 

 of this yield of straw to produce seed may be greatly enhanced by the 

 addition of calcium sulphate or sodium sulphate to the so-termed com- 

 plete-fertilizer ration. In future investigations the writers plan to 

 determine whether the indications here obtained with the Gramineae 

 express a general and fundamental sulphur requirement of this family of 

 plants. 



The influence of the concentration of the soil sulphates on the sulphur 

 content of plants has already received consideration (9), but it will not 



