WATER SOILS. 113 



vegetation until danger from frost is past, and in the fall as a warm 

 body of water leugtbens the growing season by its near influence. 



Available potash and phosphoric acid in soils, T. B. Wood {Jour. 

 Chcm. Soc, 1896,Apr.,pi).;287-202). — This is a report of tests according 

 to Dyer's method of the soil of the experimental plats of the Norfolk 

 Chamber of Agricnlture and of Suffolk County Council, used for com- 

 parative tests of fertilizers on barley (5 plats), ruta-bagas (3 plats), and 

 other crops. 



The soils used in the tests for potash are divided into 2 groups, (1) 

 those on which the addition of potash produced only a small increase 

 in the yield of barley, 1^^ bu. per acre, and (2) those on which an equal 

 addition of potash produced a large increase in yield, from 22 to 45 bu. 

 The amount of potash in these soils soluble in hydrochloric acid (1 part 

 of acid to 1 of water) and in 1 per cent citric acid was determined, 

 showing that while all of the soils were well supplied with potash 

 there was twice as much available potash in the soils of group 1 as in 

 those of group 2, a result agreeing well with the results of the fertilizer 

 experiments. 



The soils of 3 plats planted to ruta-bagas (Swedes) and which 

 responded in different degree to applications of superphosphate was 

 examined for total (soluble in nitric acid) and available (soluble in 1 

 per cent citric acid) phosphoric acid. The results agreed i^erfectly 

 with those obtained in the field experiments, the method appearing to 

 give even better results with phosi^horic acid than it did with potash. 



When the suggestion of Dyer "that in order to make the results 

 strictly comparable for all soils sufficient citric acid should be added 

 to neutralize all the chalk in the soils and leave 1 per cent over" was 

 followed it was found that " the amount of potash dissolved was nearly 

 equal in the case of each of the 3 soils tried, and the amount of phos- 

 phoric acid dissolved increased rapidly as the percentage of lime 

 increased." 



In the author's opinion the clearest indication of the amount of 

 available potash and phosphoric acid is obtained by extracting with 1 

 per cent citric acid without regard to the amount of lime in the soil 

 and that by so doing the analyst is imitating more closely the condi- 

 tions under which plants obtain their potash and phosphoric acid than 

 in the other method, since " there is no evidence to show that the acid- 

 ity of the root juice is greater when the soil is more calcareous." 



The rapid and exact determination of lime in arable soils, A. 

 Nantier {Ann. Agron., 22 {18.96), JSfo. 5, pp. 245, 246). — Five grams of 

 soil is placed in a glass flask with 50 cc. of nitric acid (100 cc. of which 

 saturates 5 gm. of pure calcium carbonate) and boiled 4 or 5 seconds 

 to drive off carbonic; acid. Fifty cubic centimeters of cold water and a 

 few drops of litmus are then added and the excess of acid titrated with 

 a solution of soda of the same strength volume by volume as the nitric 

 acid used. 



