302 EXPEEIMENT STATION EECOKD. 



that with a single solvent it is not possible to determine the assimilable 

 nutrients contained in the soil with reference to all plants. The expressions 

 " assimilable phosphorus " or " assimilable potash " should therefore be elimi- 

 nated as they are confusing, and it is better to eini)loy the general term "' easily 

 soluble substances," as estimated by the von Si.c;mond method. 



Contribution to fertilizer and soil analysis, E. A. Mitscherlich et al, 

 {Laiidtc. Jahrh., 3d (1910), Jo. 2, pp. 299-.33Ji, pis. 2, fig. i).— The authors draw 

 attention to the fact that while the methods for fertilizer and soil analysis and 

 their results are sufficiently accurate for the buyer and seller they do not fur- 

 nish a satisfactory explanation for the variations in results obtained with the 

 same fertilizer during plant growth. 



The solubility of a fertilizer depends upon four factors, namely, the time, the 

 temperature, the carbon dioxid content of the solvent, and the amount of 

 solvent. It appears from the results obtained with dibasic and tribasic calcium 

 phosphate, however, that the time factor can be lessened to a great degree by 

 using larger amounts of water, and that it also depends to a great degree upon 

 the nature of the phosphoric acid fertilizer. In regard to the relation of the 

 carbon dioxid content to the rapidity of solution, it appears that the rate of 

 solution is directly proportional to the amount of carbon dioxid in the water 

 and the undissolved salt which is present. The function of temperature seems 

 to be to increase the solution rate of iihosphoric acid in the presence of potash 

 and nitrogen salts, but with phosphoric acid and calcareous salts this was not 

 the case as a temperature varying between 10 and 20° C. seeuied to be the 

 culminating point. 



In order to estimate the actual amount of solvent required for extracting the 

 phosphoric acid in fertilizer analysis, with particular relation as to how much 

 would be taken up by the plant, the authors have compiled two tables, one 

 which is a summary of the results of solution experiments with water saturated 

 with carbon dioxid at a temperature of 30° C. and a time limit of 24 hours, and 

 the other a table which had been calculated for the same purpose. 



For nitrogen fertilizers only such materials were selected as contained nitro- 

 gen in several forms, for instance, Peruvian guano and one prepared from red 

 clover. It is shown that a definite carbon dioxid content in a water has no 

 effect on the solubility of the nitrogenous bodies. Time also had no influence, 

 and the effect of the amount of solvent was practically negative. In a test to 

 determine whether carbonated water had any selective action upon the various 

 forms of nitrogen present, it was found that with the Peruvian guano 6.8 per 

 cent was insoluble and with clover hay 62 per cent, which, according to the 

 theory of the authors, is considered *' nouavailable matter." 



From the results of the soil tests appended it appears that the results hold 

 good for soils as well as for fertilizers. 



A new method for estimating' potash in soils, L. E. Cavazza (Nuovo Metodo 

 per Dosare la Potassa. Alba, 1910, pp. 8). — The soil, which has been dried at 

 100° C, is digested in 10 per cent hydrochloric acid on the water bath. To the 

 solution obtained therefrom oxalic acid is added, the solution evaporated to 

 dryness, ignited, and weighed as potassium carbonate. 



Bacteriological methods for determining the available nitrogen in fer- 

 tilizers, J. G, LiPMAN (Jour. Indus, and Engin. Chem., 2 (1910), No. Jf, pp. 

 JJ/G-UiS). — The use of tests of the rate of ammonification in addition to nitrifi- 

 cation is explained. 



A mechanical agitator for phosphate analysis, R. Frailong (Bui. Assoc. 

 Cliim. Hucr. ct Distill., 27 (1910), No. 9. pp. SH'i-SGG, figs. 3).— A description 

 and an illustration of the apparatus are given. 



