1917] SOILS FERTILIZERS. 23 



effects of gj'psuiu, acid phosphate, rock phosphate, alone and with gypsum, and 

 moDocalcium phospliate on sulfoflcation, on ammonification, and on the yields 

 of oats in pots in the greenhouse," are reported. The soil used was a loam, high 

 in organic matter and having a basic reaction. 



It was found that " the sulphate content of the soil varied only slightly from 

 one sampling to the next. There were no sudden or striking changes in the 

 amount of sulphates present in the soil kept fallow in the greenhouse. The 

 sulphate content of soils in the field is subject to the same influences as the 

 nitrate content, but the effects are probably much less pronounced. 



" Calcium sulphate, monocalcium phosphate, acid phosphate, rock phosphate, 

 and rock phosphate plus gypsum increased the sulfofying power of the soil. The 

 sulphate alone and phosphates alone had greater effects than combinations of 

 the two materials, as in acid phosphate. All the materials used increased the 

 ammonifying power of the soil, but the differences between the effects of the 

 various substances were not pronounced. The rock phosphate had less effect, 

 however, than the other materials. 



" The sulfoflcation tests and ammonification tests did not always run parallel, 

 although very similar effects of the materials used on the two processes were 

 noted. The phosphorus fertilizers, except monocalcium phosphate, increased 

 the yield of oats, the acid phosphate to a greater extent than the rock phosphate. 

 The sulphate had no effect on the crop yield. . . . 



" The crop yields, sulfoflcation, and ammoniflcation results were not always 

 parallel. In general it appeared that on this soil increases in sulfoflcation were 

 not necessarily parallel with increases in yields. The ammoniflcation results 

 were not conclusive, but indicate that materials supplying plant food constitueuts 

 which are lacking in the soil may be of double value because of increases in the 

 production of other plant food constituents in an available form." 



Further experiments with a heavy black woodland soil, a typical river bank 

 sand in sod, two humus soils, and a river terrace cornfleld soil are also reported, 

 the purpose of which was to ascertain whether the 10-day incubation period 

 allowed the greatest differentiation between the sulfofying powers of soils from 

 different sources and under varying treatments. " Shorter periods of incuba- 

 tion were eliminated . . . and the tests were carried out at 7, 10, 12, and 14 

 day periods." The effects of gypsum, calcium carbonate, and magnesium car- 

 bonate on sulfoflcation were also studied. 



It was found that " in the use of the free-sulphui'-fresh-soil method for testing 

 the sulfofying power of soils the incubation period should be 14 days at room 

 temperature to give the most conclusive results. Ten days' incubation gave the 

 relative sulfofying powers of soils quite accurately, but the differences were 

 much more distinctive for the longer period. 



" Calcium sulphate in ordinary applications had no detrimental effect on 

 sulfoflcation, but very large applications might decrease the rate of oxidation 

 of sulphur. Calcium carbonate in ordinary applications on acid soils increased 

 sulfoflcation considerably and even in excessive amounts affected sulphur oxida- 

 tion favorably. Magnesium carbonate in small amounts increased sulfoflcation, 

 but in large amounts depressed it even below that in the same soil with its 

 acidity unneutralized. Magnesium carbonate and calcium carbonate in combina- 

 tion exerted a beneflcial influence on sulfoflcation when used in small amounts. 

 Larger applications, however, depressed the oxidation of sulphur. The effects 

 of the combined material were less than those of the calcium carbonate alone." 



Some effects of litter on the fermentation of manure, W. E. Tottingham 

 (Jour. Indus, and Engin. Chem., 8 {1916), No. 6, pp. 511-515, figs. 4). — Experi- 

 ments conducted at the Wisconsin Experiment Station on the chemical changes 

 72628°— 17 3 



