726 EXPERIMENT STATION EECORD. 



stance and the mineral parts of the soil. The organic snbstance of cultivated 

 soil by a series of fermentative processes becomes miiieralized and in this 

 fermentative process the organic nitrogen is clianged to carbonate of ammonia. 

 The carbonate of ammonia, like other anniioninm salts, reacts with the minerals 

 of the soil, making insolnble its ammonia and thus protects it from the washing 

 effect of rain. 



The author has been able to demonstrate to his owai satisfaction that by the 

 action of the dilute solution of carbonate of anmionia upon leucite a compound 

 is formed — anmionio-leucite — that contains ammonia in place of potash, am- 

 monia that does not yield to water, but that can be easily set free by an alkali 

 or by heat. 



What are the laws controlling' the assimilation of potash from the soil 

 by plants? G. Wimmer et al. (Arlj. Dent. Landw. GcselL, 1908, No. I'/S. i^p. J69; 

 </&.s-. //( Mitt. Dcat. Landw. GeseU., 23 (1908), No. 30, pp. 25J,, 255; Chem. Ztg., 

 33 {1909), No. 8, Repert., p. 32). — This subject is discussed on the basis of long 

 series of experiments with special reference to the utilization of the potash of 

 the soil and of that applied in fertilizer, and with a view to determining the 

 conditions under which potash manuring is likely to be profitable. The func- 

 tion of potasli in plant life is explained, the methotl of the experiments is de- 

 scribed, and the results are discussed in detail. 



It is shown that the assimilation of potash from the soil by the plant depends 

 in the first place upon chemical process, upon al)S()rption of potash by the soil, 

 upon soil moisture condition.^, upon the season, and finally upon the fertilizing; 

 in the second place upon the return of potash from the plant to the soil, the 

 action of lower organisms, and absorption of potash by nematodes. The 

 absori)tive power of soils for potash incieases the longer potash manuring is de- 

 layed. Fixation is more rapid in moist soils than in dry. Potash is therefore 

 better utilized in a dry se:ison than in a wet season, and assimilation is more 

 evenly distributed throughout the growth of the plant. In absorptive soil, 

 therefore, benefit is to be expected from potash manuring only when potash 

 enough is su])plied to more than satisfy the absorptive capacity of the soil. 



The assimilation of i)otash is increased by liberal applications of nitrogen 

 and phosphoric acid. The fact that many plants contain less potash when ripe 

 than at the time of greatest growth is thought to indicate that some of the pot- 

 ash finds its way back to the soil. A considerable amount of potash is rendered 

 available by lower organisms in the soil. On the other hand, it has been shown 

 that nematodes take up a considerable amount of jtotash, which is thus rendered 

 unavailable for the rest of the season. Treatment of the soil with carbon 

 bisulphid by killing the nematodes releases this potash and thus benefits the 

 crop. 



While present knowledge does not furnish a basis for positive judgment in 

 advance as to whether a given soil will benefit by potash manuring, chemical 

 analysis, esi)ecially determination of potash-absorbing constituents, will aid 

 field experiments to this end. 



Comparative tests of the agricultural value of phosphoric acid of ordinary 

 superphosphate, of dried and calcined phosphate and of metaphosphate of 

 lime, M. de Molinari and O. Ligot (A)ui. Grmbloiix, 18 (1908), No. 9, pp. 

 J/99~503. pi. 1). — This investigation was undertaken because it had been ob- 

 served that many commercial superphosphates contained considerable amounts 

 of calcium metaphosphate resulting from the heating of the monocalcium phos- 

 phate in the process of drying. 



The experiments, which were made with oats grown in pots, show that in 

 sandy clay soil under the experimental conditions superphosphate dried at 160° 

 and superphosphate dried and calcined gave results similar to those obtf'jiec' 



