Importance of Nitrogen to Gro\vth of Plants. 



249 



and analyzed by Bizzell, on these two plats and also on plats 726 and 729, 

 both being untreated plats adjacent. (See Cornell Bui. 241.) 



A sample of the field-cured hay from each were taken and the per- 



centage of water and nitrogen determined. 



Table XVII. Showing Pounds of Water-free Hay, Nitrogen Added and 

 Recovered and NO3 in Soil at Dates Mentioned. 



Plat No. 



725 

 726 

 728 

 729 



Treatment. 



320 lbs. Nitrate of Soda 



Nothing 



640 lbs. Nitrate of Soda 

 Nothinsf 



Nitrogen per acre, 

 lbs. 



Recovered. Added 



45 

 20 



56 

 16 



50 

 o 



100 



o 



Of one thing there can be no doubt, viz., that more nitrogen was 

 recovered where nitrate of soda was applied. That proportionately larger 

 amounts were not recovered when double the amount was applied is 

 doubtless due to the timothy having reached its limit of possible growth 

 under the conditions, since much of the timothy on the plat receiving 

 640 lbs. nitrate of soda became lodged on account of its rank growth. 

 It is, of course, easy to assert that the nitrogen in the plants did not 

 come from the nitrogen in the nitrate of soda, but that the nitrate of 

 soda had some indirect influence. Since no one has shown such indirect 

 influence on the part of nitrate of soda, it is much simpler and a great 

 deal more convincing to assume the direct influence of nitrate of soda 

 as a plant food. If this is admitted we must then admit that this soil did 

 not contain enough plant food in available form and at the right time 

 to grow a maximum crop of timothy. 



The experiment further indicates that the timothy consumed most 

 of the plant-food available. It is unfortunate that we did not have 

 determination of the water-soluble nitrogen immediately before and im- 

 mediately after applying the nitrate of soda. However, on this same type 

 of soil in another experiment where 320 pounds of nitrate of soda were 

 applied to the new seeding of timothy and where but little vegetation was 

 produced the average amount of NO3 in four determinations May 22, 

 June 5, June 25 and July 16, was 58.8 parts per million. Omitting 

 July 16, the average of three determinations was 69.8 parts per million. 



Since not all of the nitrogen applied was recovered, the question may 

 be raised as to what became of the rest of the nitrogen. Let us suppose 

 that 58.8 parts of NO3 per million of dry soil became soluble when we 



