182 



ANNUAL REPORT OF THE 



Off. DoC; 



per cent, in the amount of acidity corrected and this becomes more 

 marked as the limestone becomes coarser. 



When the soil becomes sweet nitrates are formed. This change 

 of nitrogen into a form in ivhich the phints can use it, is called nitri- 

 fication. The following figures show the extent to which nitrates 

 were formed. These figures are stated in parts per million of nitro- 

 gen: 



Burned lime, 



Ground limestone (100 mesh), 

 Ground limestone (60 mesh), . 

 Ground limestone (20 mesh), 

 Ground limestone (8 mesli), .. 



143 



82.9 

 80.3 

 37. 

 6.8 



It may also be of interest to observe the results as gauged by the 

 growth of plants. Clover and -oats were grov/n and the following 

 figures are based upon the percentage of increase over plats which 

 were not treated: 



Burned lime 



Ground limestone (lOO me.sh), 

 Ground limestone (SO mesli), 

 Ground limestone (20 mesh), 

 Ground limestone (8 mesh). 



Oats 



19.8 



19. 



18.5 



13.1 



12.6 



These experiments have not been in progress long enough to draw 

 definite and comprehensive conclusions. They do, however, seem to 

 sliow the trend. If limestone is used it should be finely ground, prob- 

 ably not larger than 60 mesh. The finely ground limestone will give 

 approximately as good results as burned lime although it is neces- 

 sary to use practically twice as much per acre. 



Lime improves the pliysical condition of heavy soils and it is 

 some times true that burned lime will therefore have a better af- 

 fect than limestone. 



HUMUS IN THE SOIL 



By ROBERT S. SEEDS, Birmingham, Pa. 



Mr. Chairman, Ladies and Gentlemen: I want to say that I was 

 down at Bloomburg last week and talked on soil, and they kept me 

 on the platform all afternoon, and at the close of it. Brother Martin 

 said: "Come up to our round-up and give us the same talk." I have 

 been talking soil for eighteen years, and am still on the subject. Every 

 man on the platform this morning has been a student of mine. 



