274 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



belong to the order of Monimiaceae. The authors describe it as 

 Campomanesia thea. — S. E. W . 



Sodium as a Partial Substitute for Potassium. By B. L. 



Hartwell and F. E. Pember {U.S.A. Exp. Stn. Rhode L, 21st 

 Ann. Rept. part 2 (1908); pp. 243-285; plates). — Experiments on the 

 replacement of potassium by sodium in continuation of those already 

 reported (see Journal E.H.S. xxxiv. p. 594) are discussed. It is 

 concluded that sodium is able to replace potassium in certain of its 

 functions but not in all, and that in the principal functions of potas- 

 sium, sodium cannot replace it. Thus, unless a sufficient amount of 

 potassium is present to enable these functions to be performed maximum 

 growth cannot be secured. Less potassium, however, is absorbed when 

 that element is supplemented by sodium than when it is not, so that 

 sodium acts as a conserver of potassium. — F. J. C. 



Soil Fertility. By Thomas F. Hunt (U.S.A. Exp. Stn. Pensyl- 

 vania, Bull. 90; March 1909; 13 tab., 7 charts). — A series of experi- 

 ments with fertilizers has been conducted for twenty-five years on 

 a clay loam soil of limestone origin. The series consists of four tiers 

 of 36 plats each in a rotation consisting of corn, oats, wheat, and hay 

 (mixed timothy and clover). Fertihzers were employed in alternate 

 years, viz. to the corn and wheat. 



Of the three essential fertilizing ingredients, nitrogen, potash, and 

 phosphoric acid, only the latter produced any increase of yield when 

 used alone. A much larger increase was obtained by using both potash 

 and phosphoric acid. There is no evidence thus far to show that the 

 supply of nitrogen cannot be definitely maintained on this limestone 

 soil by means of a rotation containing clover, provided the mineral 

 fertilizers are abundantly supplied. 



The addition, however, of 24 lb. of nitrogen an acre to the mineral 

 fertilizers has resulted in a material increase in yield ; greater quan- 

 tities of nitrogen produced very little effect. Nitrate of soda has 

 proved a better form of nitrogen than dried blood or sulphate of 

 ammonia; the continuous application of the latter caused acidity in 

 the soil. It has been possible during twenty-five years to maintain 

 the crop -producing power of the soil without the use of any yard 

 manure. — V. G. J. 



Soil Nitrogen. By Henry G. Knight and Frank A. Smith (U.S.A. 

 Exp. Stn. Wyoming, Bull. 82; June 1909; 4 figs., 1 plate).— The 

 bulletin deals with the chemical and mechanical conditions that go to 

 make a fertile soil, and describes the several classes of nitrifying bac- 

 teria which work upon the organic nitrogen present in the soil. Results 

 are given of experiments in fertilizing with legumes and nitrate of 

 soda.— F. G. J. 



Soils, Absorption by. By H. E. Patten and W. H. Waggaman 

 (U.S.A. Dep. Agr., Bur. Soils, Bull. 52, Aug. 1908).— This bulletin 



