558 



VARIOUS FERTILITY FACTORS 



six years, also of Agdell field after the wheat crop had been har- 

 vested, in the legume system and the fallow system, for which the 

 yields are recorded in Table 57. 



TABLE 117. SOLUBLE NITROGEN IN CROPPED SOILS RECEIVING NO NITROGEN 

 FERTILIZER SINCE 1849 (Pounds per Acre) 



The crops of white clover were too small to cut in 1880, 1883, and 

 1884, and in other years only a single cutting was harvested. 

 Thus most of the rather small amount of produce was left to decay 

 upon the white clover plot. Evidently 87.1 pounds of nitrate 

 nitrogen has escaped beyond the reach of the white clover roots, 

 while almost no soluble nitrogen (5.4 pounds) was found in the 

 same stratum (3 to 9 feet) under alfalfa. The root system of vetch 

 is perhaps even less extensive than that of white clover (see Table 

 36), but the annual decay of the roots possibly gives it the inter- 

 mediate position in loss of nitrogen as indicated, although a different 

 season may perhaps have given quite different results. The data 



