192 2] WOOD ARD— SOIL FERTILITY 83 



was reported for the same treatment on other crops. Brooks (9) 

 also made a comparison of different phosphate fertilizers. He 

 found that acid phosphate and dissolved boneblack, which contain 

 sulphur, gave greater increases in crop yields than raw bonemeal 

 and rock phosphate, which contain little or no sulphur. A more 

 rapid early growth of both tops and roots and earlier maturity 

 were observed on the plots receiving the dissolved boneblack and 

 acid phosphate than on the plots receiving raw bonemeal and rock 

 phosphate. 



The use of flowers of sulphur as a fertilizer was observed to 

 have an influence aside from its effect in destroying the fungi which 

 cause plant diseases. Mares (50) noticed a much greater vigor 

 in vines that had been sulphured than in those which had not. 

 He found that the sulphur was oxidized to sulphuric acid in the 

 soil, and he thought that the sulphuric acid acted on the insoluble 

 compounds containing potassium and made the potassium soluble. 

 Demolon (16) found that heating the soil prevented the oxida- 

 tion, and so he concluded that oxidation was caused by micro- 

 organisms. Pfeiffer and Blanck (56) obtained no increased 

 yields of oats for the use of flowers of sulphur in field experiments. 

 Feilitzen (21) in Europe, and Sherbakoff (64) in the United 

 States both obtained increased yields of potatoes from the use of 

 flowers of sulphur. 



BouLLANGER and DuGARDiN (3) found flowers of sulphur in- 

 creased ammonification but decreased nitrification. The harmful 

 effect on the nitrifying bacteria was probably due to the acidity, 

 as Lint (38) found that the oxidation of sulphur in the soil in- 

 creased the acidity very much. Fred and Hart (23) report an 

 increase in ammonification from the use of gypsum in peptone so- 

 lutions, and Warington (73) obtained an increase in nitrification 

 when gypsum was applied to solutions of urea. Greaves, Carter, 

 and Goldthorpe (24) studied the influence of calcium sulphate 

 on production of nitrates and found it caused a great increase in 

 all concentrations used. The increase was very high for the higher 

 concentrations of calcium sulphate. 



Brioux and Guerbet (7) found that flowers of sulphur 

 increased availability of calcium and potassium in both calcareous 



