88 Journal of Agricultural Research voi. xvii, No. 3 



They report no increased yield when sulphur was applied as potassium 

 sulphate (KjSOJ, but state that the loss of sulphur can not continue 

 without affecting crop yields. Hart and Peterson (11) calculate from 

 data obtained at the Rothamsted Experiment Station, Harpenden, 

 England, and the Wisconsin Experiment Station that the loss of sulphur 

 in drainage water is three times that brought to an acre surface from 

 the atmosphere. 



Results of the investigations mentioned above show that the soil is 

 capable of producing sulphate sulphur and that there is a tremendous 

 loss of such sulphur in the drainage water. In certain cases no benefxial 

 results have been obtained from sulphur fertilizers, which is not sur- 

 prising, but in many instances sulphur application has caused increased 

 yields. No doubt, in many soils, if the supply of sulphate sulphur 

 formed was retained for plant food, they would not respond to sulphate 

 treatment but the continual loss of sulphate sulphur and the large 

 amount needed by some plants require that additional sulphate sulphur 

 be present during the growing period to obtain better growth. A soil 

 with a high sulphur content may not supply enough sulphate sulphur in 

 comparison to the other plant food to obtain the maximum growth, 

 while conditions in a soil of lower sulphur content may be such as to 

 supply an adequate amount of sulphate sulphur. 



In addition to sulphur acting as a plant food, several other explana- 

 tions have been given as to its action in the soil. Certain investigators, 

 Bemhard (j) , Chancrin and Desriot (8) , say that it functions as a partial 

 sterilizer, others that the sulphuric acid produced acts upon the mineral 

 matter of the soil, rendering it more soluble. Lipman (15, 16) and his 

 coworkers have shown (j) that the oxidation of sulphur in sand and soils 

 has acted upon the raw-rock-phosphate so as to increase the water 

 and ammonium-citrate-soluble phosphorus (2) ; that the formation of 

 sulphate sulphur paralleled the increase of available phosphoric acid (j) ; 

 and that the sulphur-floats-soil compost could be employed as a sub- 

 stitute for acid phosphate for plant growth. Brown and Gwinn (5) 

 have found that the addition of sulphur to the soil increased the avail- 

 ability of raw-rockphosphate, the gain being greatest where manure and 

 sulphur were used together. McLean (18) in a number of experiments 

 has shown the conditions which are more favorable for the oxidation 

 of sulphur by microorganisms and production of available phosphorus. 

 Lipman (14) suggests that the sulphuric acid may act in making alkali 

 areas productive by converting sodium carbonate into sodium sulphate. 

 The favorable results obtained by adding gypsum have often been 

 attributed to the calcium liberating potassium, but the experiments of 

 Hart and Tottingham (12) show that a complete fertilizer plus calcium 

 sulphate gave increased yields over those obtained with a complete fer- 

 tilizer containing potassium chlorid, and that here the action of calcium 

 sulphate must have been direct. 



