LOSSES OF PLANT FOOD FROM SOILS 559 



from Agdell field indicate that only small amounts of nitrogen 

 escape from the wheat plant under the conditions, these results 

 being in harmony with those reported in Table 116. 



On the University of Illinois experiment field at Urbana are 

 two adjoining plots, one of which (No. 3) grew corn for 16 years, 

 while the other (No. 105) was kept in pasture In 1901 plot 3 con- 

 tained 4000 pounds of nitrogen and plot 105 contained 4914 

 pounds in 2 million of surface soil, a loss of about one fifth of the 

 total being thus indicated. 



Professor Shutt reports the nitrogen content of virgin soil and 

 adjoining cultivated soil from the Northwest Territory of Canada. 

 He says: 



"Regarding the cultivated soil, we possess a complete and authentic record 

 of the cropping and fallowing since the prairie was first broken, 22 years ago. 

 It has borne 6 crops of wheat, 4 of barley, and 3 of oats, with fallows (9 in all) 

 between each. 



"Both samples were of a composite character and every precaution taken 

 to have them thoroughly representative. It may, further, be added that there 

 is every reason to suppose that the soil over the whole area examined was origi- 

 nally of an extremely uniform nature; in other words, that at the outset the ni- 

 trogen content was practically the same for the soils now designated as virgin 

 and cultivated, respectively:" 



NITROGEN, POUNDS PER ACRE 



Virgin soil, to depth of 8 inches 6936 



Cultivated soil, to depth of 8 inches 4736 



Difference or loss due to cropping and cultural operation . . 2200 



"The results show that the cultivated soil is to-day still very rich, yet com- 

 pared with the untouched prairie it is seen to have lost one third, practically, of 

 its nitrogen. This is highly significant. Humus and nitrogen must be re- 

 turned, either as manure or by the occasional growth of certain enriching crops, 

 or fertility will inevitably decline." (Dominion Experiment Farms, Report 

 for 1905, page 128.) 



Shutt reports 3780 and 3240 pounds of nitrogen in the virgin 

 and cultivated soils, respectively, of Grindstone Island, Magdalen 

 Islands, Quebec; also 3160 and 2260 pounds of nitrogen from 

 virgin and cultivated soils from Kent County, New Brunswick. 

 The corresponding figures for acid-soluble phosphorus are 2160 and 

 1970 for the Quebec soils, and 2180 and 1070 for the New Bruns- 



