INFLUENCE OF SOIL UPON YIELD. 



27 



it 



although it thus increased the total production of nitrogen, 

 decreased the relative proportion of nitrogenous substance. 



Bogdau" conducted investigations the results of which indicated 

 that with an increase in the soluble salt content of 22 alkali soils the 

 nitrogen and ash contents of the wheat kernels increased, but the 

 absolute weight of the kernels diminished. These soluble salts are 

 rich in nitrates. 



Experiments were conducted by Whitson, WeUs, and Vivian* in 

 which plants were grown in pots the soils of which were in some cases 

 fertilized with nitrates and in others with leachings of single and 

 of double strengths from fertile soils. Field experiments were con- 

 ducted on manured and unmanured plots. All of the analyses, 

 except in the case of oats, were of the whole plant. Of the ripe oat 

 kernels those from the unfertilized soil contained 2.57 per cent of 

 nitrogen, while the average of those from the fertilized soil was 2.78 

 per cent. 



Guthrie c conducted experiments with fertilizers for wheat during 

 two years, in which he kept a record of the yield and gluten content of 

 the grain. The following is a statement of the results: 



In this experiment there was in each case a higher percentage of 

 gluten in the wheat raised on the fertilized soil than in that from the 

 soil fertilized with ammonium sulphate, and in the latter less than in 

 the grain fertilized with other material. 



The most striking feature of these results is their apparent lack of 

 uniformity. In some cases the use of nitrogenous fertilizers was 

 accompanied by an increase in the nitrogen content of the grain and 

 in other cases no increase appeared; in some cases phosphoric acid 

 fertilizers apparently increased the nitrogen content and in others 

 they did not have this effect. 



Climatic influences have doubtless operated largely in these results, 

 but they are not considered by any of the experimenters except Wolff. 



"Abstract, Experiment Station Record, 13, p. 329, from Report of Department of Agri- 

 culture, St. Petersburg, 1900. 



''Wisconsin Experiment Station Report, 19 (1902), pp. 192-209. 



Agricultural Gazette of New South Wales, 13 (1902), No. 6, p. 664; and No. 7, p. 728. 



