Importance of Nitrogen to Growth of Plants. 



245 



Here, then, was a piece of land which would not under the very 

 best of cultivation raise either mangel wurzels or cabbages, while land 

 apparently in every way identical raised satisfactory crops. It is a com- 

 mentary on our knowledge of plant growth to be compelled to confess 

 that neither scientific investigations or practical experience offered any 

 explanation. 



At this juncture the Bureau of Soils offered to send a detail of men 

 to work on any soil problems the Cornell Station might suggest. The 

 problems involved by these poor spots were investigated by Breazeale, 

 Brown, Read and Eckmann, assisted by Clark of Cornell, from about 

 November i to May i. Without going into details with regard to either 

 the cabbage or timothy spot, it may be stated that the soil on the poor 

 spots when tested according to the basket method grew better crops 

 than the soil from the good areas, and plants grown in the soil extracted 

 behaved in a similar manner. Further, the only difference discovered 

 between the poor and good spots was a much higher percentage of water- 

 soluble nitrogen on the spots that in the previous season did not grow 

 crops. For example, samples of soil from the " good " and " poor " 

 cabbage spots were analyzed by the Bureau of Soils with the following 

 results, the samples being taken in December: 



Table XIII. Analysis of Soil Extract from Cabbage Spot Stated in Parts 



PER Million of Dry Soil. 



After a number of tests of the soil and water extract on both the 

 cabbage and timothy areas had been made the author of this paper 

 suggested that since the only difference thus far discovered between the 

 poor and good spots was the percentage of water-soluble nitrogen, it 

 would be desirable to add sufficient nitrate of soda to bring the good soil 

 to the same water-soluble nitrogen content as the poor soil and then 

 determine whether plants behaved alike in both. Samples of both soils 

 were taken and analyzed by Bizzell. The poor soil contained 106.5 

 parts and the good soil 9.6 parts per million of dry soil. Since all soils 

 have the power of taking salts from solution and fixing them, it was 

 necessary to keep adding nitrate of soda until the right amount of water- 

 soluble nitrogen was found. In this case it required 135.4 parts of NO3 

 to increase the water-soluble nitrogen 96.9 parts per million of dry soil. 



