SOILS- — FERTILIZERS. 423 



apophyllite was much less available thau that of orthoclase, and the potash 

 of phillipsite was more readily assimilated than that of either. The potash of 

 the phillipsite was readily split off from the zeolites. 



The results thus obtained show that pot experiments may throw new light 

 on the chemical constitution of minerals and on the bearing of various stages 

 of weathering on the assimilation of the plant food. 



Relation of pot experiments to the active phosphoric acid of the soil, 

 G. S. FRAPS {Jour. Indus, find Engin. Chem., 2 (1910), No. 8, pp. 350-352).— 

 Active phosphoric acid is defined in this article as that which is extracted by 

 2,000 cc. of fifth-normal nitric acid from 200 gm. of soil in 5 hours at 40° C. 

 The conclusions drawn from four years' pot experiments with a large number 

 of Texas soils are as follows : 



" Soils containing 20 parts per million or less of active phosphoric acid are 

 highly deficient in pot experiments. 



" Soils containing from 30 to 100 parts per million of active phosphoric acid 

 are deficient, as a rule, in pot experiments, and the extent of their deficiency 

 is related to the quantity of active phosphoric acid in them. 



" Soils containing 100 to 300 parts per million of active phosphoric acid may 

 or may not prove deficient in pot tests, the chances being even. 



" The quantity of phosphoric acid removed by the crop grown in our pot 

 experiments is on an average closely related to the quantity of active phosphoric 

 acid. 



" The phosphoric acid removed from the soil by the crop comes from other 

 sources in addition to the active phosphoric acid." 



Relations between the fertility of the soil and the phosphoric acid soluble 

 in water, I. Pouget and D. Chouchak (Assoc. Frang. Avanc. Sci., Compt. Rend., 

 87 (1908), pp. 1195-1199).— This is a brief account of investigations which have 

 been reported in full elsewhere (B. S. R., 23, p. 519). 



On the interaction of potash and lime, Niggl (IUus. Landio. Ztg., SO 

 (1910), No. 7G, pp. 719, 720; Bl. Ziickerruhcnhau, 17 (1910), No. 20, pp. 332- 

 335). — Field experiments by Christmann are referred to as showing the inti- 

 mate relation which exists between the action of potash and of lime in the soil. 



A method for the study of soil fertility problems, J. G. Lipman (Jour. 

 Agr. 8ci., 3 (1910), No. 3, pp. 297-300, fig. 1; ahs. in Jour. Soc. Chem. Indus., 

 29 (1910), No. 20, p. 1218).— A method for the study of the reciprocal effects 

 of legumes and nonleguminous plants is described. This consists in growing 

 the nonleguminous plants in soil in a porous pot surrounded by earth in a 

 larger glazed earthenware pot in which leguminous plants are grown. Ex- 

 periments with this device compared with a similar arrangement in which a 

 nonporous inner pot was used indicated that soluble nitrogenous compounds 

 diffused through the unglazed porous wall of the inner pot and were utilized 

 by the oats growing in this pot. Various uses which may be made of this 

 method in soil investigations are pointed out. 



Work of the chemical laboratory, B. Welbel (Godichnyl Otchet Ploti. 

 Selsk. Khoz. Opytn. StantsU, 15 (1909), pp. 119-U8, 166-169, i)ls. 3).— A con- 

 tinuation of previous investigations (E. S. R., 22, p. 523) on the influence of 

 fallow, manures and fertilizers, and growth of cereals and legumes on soil 

 fertility, particularly on the balance of nitrogen and phosphoric acid in the 

 soil, is reported. 



The results in 1909 confirmed those obtained the previous year. Fallowing 

 increased the amount of assimilable nitrogen and phosphoric acid; culture of 

 cereals did not greatly decrease the assimilable phosphoric acid of the soil ; 

 and the culture of legumes increased the assimilable nitrogen but greatly de- 



85408°— No. 5—11 3 



