SOILS FERTILIZERS. 213 



kinds and liotwooii wators of Ihc saiiio kind roprosontiiiK diffoi-ciit dogivos of 

 l)ollution is wfli marked hy (•taints at tliis tonijK'i-aturo. 



On the progress of self-purification in water, IIofku iMituchcu. Mrd. 

 Wchiisclir.. :,.i (UK).-)), lip. ,Li(>l)-ii6i): dh.s. in Chciii. Ccntbl., 1906, JI, No. 7, 

 I). 637). — A discnssion of chemical and biological i)rocesses with special refer- 

 ence to the Isar. 



SOILS FERTILIZERS. 



Studies of Wisconsin soils, A. It. Wiiitsox and ('. W. Stoddart (Wisconsin 

 Sta. Rpt. l!)(i.-), pp. .^62-2SJ. fir/x. U. map 1) . — The soils of the State are classified, 

 chiefly accordinj^ to orijiin, and tlie different classes are described and mapped 

 as follows: (1) Red clay, chietiy of lacustrine origin, (2) last glacial clay on 

 crystalline rock, (.']) old glacial clay on crystalline rock, (4) last glacial clay 

 on limestone and sandstone. (5) old glacial clay on limestone and sandstone. 

 ((>) residual clay on limestone, (7) sandy soils of last glacial period, (8) resid- 

 ual sandy loam soils of Potsdam sandstone, (0) residual sandy soils of Pots- 

 dam sandstone, (10) loess or soils chiefly of wind origin, and (11) nuick and 

 peat soils. 



The methods of chemical analysis used are described and the results of analy- 

 sis of the different type soils are briefly reported, and an experiment begun by 

 F. II. King, in which a study has been made of the changes which take place dur- 

 ing the exliaustion of soil fertility by continuous cropping, is reported. In 

 these expei-iments a virgin soil has been cropped practically continuously for 8 

 years in cylinders 18 in. in diameter and 42 in. in depth, 20 of the cylinders 

 being cropjied with corn, 8 with oats, G with potatoes, and 14 with common red 

 clover. 



To determine the fertilizing constituents in which the soil was deficient 

 various kinds and combinations of fertilizing materials vA'ere applied to the soil, 

 and chemical analyses were made of the soil at the beginning and end of the 

 series of experiments. The results show that the supply of available pot-ish 

 was more completely exhausted than that of any other element, although in the 

 case of oats the available nitrogen and phosphoric acid were also insufficient. 

 Chemical analysis showed that the most noticeable change which had taken 

 place in the soil was the reduction of the organic matter from 3.24 per cent to 

 2.22 per cent " and suggests that the potassium which has been used by the 

 plants grown on this soil has come chiefly from the organic matter which has 

 been decomposed." 



Experiments with peat soils which were begun in 1904 (E. S. R., Ki, p. T"m) 

 were continued during 1905 on a farm at Marinette, Wis., the object of the ex- 

 periments during this year being " first, to determine the fertilize:- recjuire- 

 ments of the soil in its .virgin condition ; second, the availability of untreated 

 rock phosphate; third, the relative adaptability of different grasses for hay; 

 and, fonrtli. the effect of ground limestone used to neutralize the acidity of 

 this soil." 



Experiments witii grasses, barley, and oats are briefly reported. Tbe season 

 was; unfavoraI)le and tlie results are considered inconclusive. 



[Acidity and nitrogen in Hawaiian soils], E. ('. Siiorky ( C ^'. lUpt. A (jr., 

 Office Expt. Stas. liul. 170, pp. 28-37). — A brief preliminary report is given on 

 acidity determinations in 25 samples of soils by the method of Hopkins, Knox, 

 and Pettit. Only 2 samples were acid to litmus paper, but all gave acid 

 solutions when extracted with 5 per cent salt solution. The acidity apparently 

 did not interfere to any great extent with nitrification, since the soils exanuned 

 contained from 15 to 55 parts per million of nitrates. It was observed tliat 



