SOILS FERTILIZERS. 427 



t>xh;uistod I>y cultivation ;ii\(l liy percolatiui,' i.iiu waler. " For exaiiii)!*', the 

 Itothiiiusted soil, which at the bi'trimiing of the ninctccntli century must have 

 contained soniethin.tr like a hundred tons of chalk pci- acre, has now less than 

 tifty. and many other soils wlii'-h started with a smaller initial stock are be^in- 

 nin.ir to run danj^erously short. All over the coimtry there is evidence that 

 mvich of the land, especially on the heavier soils, is in need of liming, and 

 thouirh it would not be wise to return to the old wasteful dressings of 6 to 10 

 tons to the acre, a much smaller (piautity. half a t(m or so per acre, could be 

 profitably applieil at least once in the c(mrse of each rotation." 



The chemical and physical action of salt water on soils, I). .1. IIissink 

 (CIiciii. ]V((l,bI.. .! (JHOC). pjK S'l.'j-.'iO.J : (thx. hi Cliciii. CciilhL, HXXi, //, \u. J,, 

 p. So.': Jitiir. Chcm. Sac. [Londoiil. '._)() ( I'JOG) . Xo. 5^8, II, pp. 701, 70i).— In- 

 vestigations are reported which show that the chemical action of small amounts 

 of salt water, as in case of lands occasionally overflowed by sea water, is in 

 general beneficial in increasing the solublity of most of the soil constituents. 

 The physical effects, however, are not so favoi'able. the salt water tending to 

 puddl(> and compact the soil. 



The effect of fertilizers on the reaction of soils, F. I'. ^■EITC^ (Science, n. 

 •s-r/-.. .^3 tlUOd). .Vo. .-,!).!. pp. 770-77.3).— See E. S. K.. IT. p. 4:',1. 



On the insoluble alkaline compounds formed in dead leaves, ^I. Bertiielot 

 I A II II. Chilli, ct I'hi/s., 8. scr., 8 (1906), Maij, pp. SO-'fl). — Investigations are 

 reported which show that dead leaves contain considerable amounts of alkaline 

 compounds insoluble in water, particularly salts of potash, which exhibit the 

 phenomena of double decomposition and equilibrium with solution of salts of 

 weak acids, such as acetic acid. 



On the insoluble alkaline compounds formed in the organic matter of 

 soils, M. Berthelot (Ann. Cliiiii. ct I'Jii/.'i.. 8. scr., 8 (1906), Map. pp. '/i-.'/.Ti. — 

 The ex]ieriments here reported yielded results similar to those obtained in the 

 case of dead leaves noted above. 



On the insoluble alkaline compounds formed by artificial humus com- 

 pounds of organic oi'igin, M. Berthelot (Ann. Chini. ct Flips.. 8. scr.. 8 

 (190()), Map, pp. .'lo-.jj). — By repeated treatment with hydrochloric acid a hu- 

 nuis compound was obtained from soil which contained from .3 to 4 per cent < f 

 nitrogen. When this substance was treated with potash solutions a salt wa ; 

 obtained which on prolonged washing lost the major part of its potash but still 

 retained from 3.7 to 0.2 per cent of insoluble potash. 



Similar results were obtained with dead leaves and with comjiost. 



Experiments with wood charcoal, M. Berthelot iAiin. CJiiin. ct Plips.. 8. 

 .scr.. 8 (19116). Map. pp. .7 /-.j 7). —See E. S. R., 17. p. 842. 



Irrigating sediments and their effects upon crops. It. H. Forbes (Arizona 

 sta. Bui. .7J, pp. .5-')-08. fir)s. 10). — This bulletin reports the results of a study of 

 the fertilizing and physical effects of sediments upon soils, in continuation of 

 previous work along this line (E. S. R., 14, p. 423). 



In this investigation a study has been made not only of the effect of ordinary 

 stream sediments but of mine tailings from concentratin.g ])lants. The streams 

 of the Southwest carry unusually large amounts of sediments, particularly in 

 times of fiood. Measurements are reported which show that the Gila River at 

 Florence carries an annual average of 10.23 tons of silt per acre-foot, the Salt 

 River at ^IcDowell 1.2 tons, the Colorado at Yuma 9.02 tons. The amounts of 

 fertilizing materials in these sediments are calculated to be. for the Gila River. 

 214.3 lbs. per year of potash. .30.1> lbs. of phosphoric acid, and 2S.1 lbs. of nitro 

 gen : for the Salt River, 18 lbs. of potash. 0.0 lbs. of i)hosphoric acid, and 5.5 lbs. 

 of nitrogen; fur the Colorado River. 113.1 lbs. of potash, 10 lbs. of phosphoric 



