April, 1940] PASTURE TOP-DRESSING IN N. H. 9 



Nitrogen Fertilizers Compared 



During the course of these two experiments, certain of the com- 

 mon nitrogen carriers have been used annually on different plots for 

 comparison. These have all been used in equivalent amounts of ni- 

 trogen, 50 pounds of elemental nitrogen per acre. 



Because of the difference in rate of availability various carriers 

 have been applied at different times in the spring. To avoid burn- 

 ing the grass and because of its slightly slower availability cyanamid 

 has been applied annually about April 1, while sulphate of ammonia 

 has usually been spread about April 15, with the nitrate of soda and 

 cal nitro applications around April 25. \'ariations in the time of ap- 

 ])lication have been due to seasonal differences. In a very late spring 

 for example, the actual time might be five or ten days later than the 

 dates given. It has been felt that this difference in time might 

 equalize the net effects of the materials so far as it is within the 

 power of those who apply them. 



Certain minor changes in treatment were made on some of the 

 nitrogen plots on Livingston pasture in 1938 and on Seavey in 1939 

 so that we have a five-year average on Livingston and seven years' 

 record on Seave}' for these treatments. The average annual yields 

 with check plot comparisons are presented in Tables 8 and 9. These 

 are arranged in descending order according to yields of protein per 

 acre. 



Table 8. — Seven year average yield, Seavey pasture 



Pounds per acre Difference from check 



Plot No. Treatment Dry matter Protein Dry matter Protein 



18 Sulphate of ammonia, 250 lbs. 



8_ Nitrate of so_da, 3\2 lbs. 



17 Cyanamid, 250 lbs. 



2-9-16 Ave. yield check plots 



Perhaps the most interesting point in connection with Tables 8 

 and 9 is that the sulphate of ammonia treatment stands first in Sea- 

 vey and last in the Livingston pasture. It is a well-known fact that 

 sulphate of ammonia increases soil acidity and this treatment is def- 

 initely inimical to clover. However, since very little or no clover 

 appeared under any of the nitrogen treatments in either pasture, 

 acidity alone can scarcely account for the dift'erences secured. How- 

 ever, the grass in the two pastures looks very different after being 

 top-dressed with sulphate of ammonia, that in the Seavey pasture 

 looking entirely healthy, that in Livingston assuming a reddish hue 

 shortly after treatment. This red color disappears later in the sea- 

 son but after its disappearance the foliage is darker than that of 

 other nitrogen plots. 



Nitrate of soda has given a good account of itself in both pastures. 

 standing first in Livingston (Table 9) and running a very close sec- 

 ond to sulphate of ammonia in Seavey (Table 8). 



These data for nitrogen treatments are presented for the interest 

 they bear and not because nitrogen alone is a recommended treat- 



