LOSSES OF PLANT FOOD FROM SOILS 



557 



TABLE 116. NITROGEN IN DRAINAGE WATERS: ROTHAMSTED EXPERIMENTS 

 Average of 12 Years (or More) 



While the drainage water from the bare uncropped soil of the 

 drain gauge contained 11.4 parts of nitrogen per million during the 

 summer months (June to August), the drainage water from the 

 land on which wheat was growing (Broadbalk plots 3 and 4) con- 

 tained only .1 pound of nitrogen per million pounds of water, as 

 an average of the three months. After the wheat harvest, the loss 

 of nitrogen in the field drains quickly rises to about 4 pounds per 

 million. In loss per acre the differences are much greater, because 

 during the growing season the quantity of drainage from the field 

 is probably even less than that from the drainage gauge, and the 

 data from the gauge show two to three times as much drainage 

 during the other months. 



In Table 117 are recorded the amounts of water-soluble nitrogen 

 found in the soil and subsoil of Hoos field, where the shallow-rooting 

 white clover (Trifolium repens) had been grown for seven years and 

 where the vetch and the deep-rooting alfalfa had been grown for 



