326 EXPEEIMENT STATION RECORD. [Vol. 36 



increasing with time and the amount of oyster shells used. With 30 and 50 per 

 cent of oyster shells virtually all the water-soluble phosphoric acid disappeared. 



A critique of the hypothesis of the lime-magnesia ratio, I, II, C. B. Lipman 

 (Plant World, 19 (1916), Nos. 4, pp. 83-105; 5, pp. 119-135; abs. in Chem. Abs., 

 10 (1916), No. 16, p. 2118). — A review of some of the more important investiga- 

 tions on the subject is given, leading to the conclusion " that in the first place 

 there is little or no evidence in support of the necessity to plants for a proper 

 lime-magnesia ratio in soils, which is specific for certain groups of plants. In 

 the second place, when certain favorable effects are noted which appear to in- 

 dicate that they follow from the adjustment of the ratio of lime to magnesia, 

 such favorable effects can easily be explained on many other grounds which do 

 not call at all for the introduction of the hypothesis of the lime-magnesia ratio." 



The effect of some manganese salts on ammonification and nitrification, 

 P. E. Bkown and G. A. Minges (Soil Scl, 2 (1916), No. 1, pp. 67-85 ) .—Experi- 

 ments conducted at the Iowa State College with clay loam soil containing 0.1732 

 per cent manganese on the effect of the sulphate, chlorid, and nitrate of man- 

 ganese and of manganous oxid on the ammonification of dried blood and the 

 nitrification of ammonium sulphate when added to the soil at rates varying from 

 0.005 gm. to 5 gm. per 100 gm. of soil (100 lbs. to 100,000 lbs. per acre) are re- 

 ported. 



It was found that " manganese chlorid in applications greater than 2,000 lbs. 

 per acre depressed both ammonification and nitrification, the depression increas- 

 ing as the size of the application was increased until a point was reached at 

 which both processes ceased. With smaller amounts of the chlorid the effects 

 on the two processes were not identical but tended in the same direction. Thus 

 the applications of 100 and 200 lbs. per acre gave increases which were slight 

 in the case of ammonification but quite distinct in the case of nitrification. 

 With amounts greater than 200 lbs. per acre and less than 2,000 lbs., however, 

 ammonification was depressed while no appreciable depression was apparent on 

 nitrification. 



" Manganese sulphate when applied to the soil at the rate of 100 lbs. per acre 

 increased appreciably both ammonification and nitrification. In amounts 

 greater than 100 lbs. per acre and less than 2,000 lbs., ammonification was 

 increased but to a smaller extent than with the 100-lb. application, but with 

 nitrification no gains or depressions were found with these amounts. In appli- 

 cations equal to or greater than 2.000 lbs. per acre, both nitrification and am- 

 monification were depressed by manganese sulphate, the depression increasing 

 with the size of the application. 



"Manganese nitrate added to the soil at the rate of 500 lbs. per acre or in 

 greater amounts depressed both ammonification and nitrification, the depression 

 increasing as the size of the application was increased. JManganous oxid when 

 applied to the soil at the rate of 2.000 lbs. per acre or In larger quantities 

 depressed both ammonification and nitrification, the depression becoming greater 

 as the size of the addition was increased." 



It is concluded that " if manganese salts in small quantities increase crop 

 yields on a soil that increase may be due in part at least to a beneficial effect 

 on ammonification and nitrification with a consequently greater production of 

 available plant food. On the other hand, if manganese salts when applied to 

 the soil restrict crop growth, that restriction may be due in part to a depres- 

 sion of bacterial activity." 



Six references to literature bearing on the subject are appended. 



Commercial fertilizers. P L. Hibbakd (California Sta. Bvl. 272 (1916), pp. 

 1^7-99), — This bulletin reports the results of actual and guarantied analyses 

 and valuations of 467 samples of fertilizers and fertilizing materials collected 



