10 MASS. EXPERIMENT STATION BULLETIN 290 



carbonate in the soil in order to be most productive as a nitrogen fertilizer. 

 The other kinds may or may not be more efficient in the presence of lime. During 

 the years of this comparison of nitrogen fertilizers, ammonium sulfate did not 

 uniformly have the conditions for good results. In some seasons, the material 

 seemed to have been positively injurious. Therefore, for the purpose of this 

 review the best two yields in each year are averaged for comparison with nitrate 

 and blood. 



The crops of oats in this group consisted of two distinct parts, grain and straw. 

 The total of the two weights will be used as the standard for rating the different 

 fertilizers, because nitrogen is especially effective in promoting growth. In this 

 group of crops there were but two instances where grain and straw had to be 

 combined for comparison. Ammonium sulfate was foremost in productiveness 

 in 1890, 1895, and 1898. Sodimn nitrate led in 1897 and blood was ahead in 1893. 

 Manure was least effective. The ratio of grain to straw varied from year to year, 

 being widest in 1893, the maximum year of both grain and straw, and narrowest 

 in the year of least production, 1898. While variety of seed oats was changed 

 from ye4ir to year, the trend of grain to straw indicated that a generous develop- 

 ment of stem and leaf was necessary for a big crop of grain. There was no con- 

 stant difference in ratios that could be attributed to any one nitrogen fertilizer, 

 but the check plots without nitrogen had narrower ratios of grain to straw than 

 any of the plots with nitrogen, which accords with the trend of the years. 



Soy Beans 



The next group of crops is soy beans, and consists of two subgroups. The 

 crops of 1892, 1894, and 1896 were alternated with the oats previously discussed. 

 A different variety was planted each year and the crop was cut for the silo and 

 weighed green. The first crop was a late variety and did not reach the blossom 

 stage. The second crop was an early variety and bore pods at harvest time. 

 The third crop was a medium season type and was well filled with pods but was 

 a much larger type of plant than the earlj' one of 1894. 



The most striking yields in these three crops are those without nitrogen. 

 Soy beans were not apparently accomplishing much at obtaining nitrogen from 

 the air. This was possibly due to the lack of the specific bacteria in the soil at 

 this period, since soy beans had been introduced only a few years before. 



The behavior of Plot 8 illustrates the benefit of lime as an accompaniment 

 with ammonium sulfate. No better than plots without nitrogen in 1892, it re- 

 sponded to the liming of 1894, which carried it to the highest standing of all in 

 1896. Why Plot 8 was most frequently the least productive of the three plots 

 treated with ammonium sulfate has never been solved. 



Plot 10, supplied with nitrogen in dried blood, was apparently no better than 

 the plots without nitrogen in 1892. In the report for that year, the suggestion 

 was made that this might have been due to a scanty seeding, as it was the first 

 plot to be sown with the seed drill. 



The crops of 1901 and 1903 were preceded and followed by potatoes. The soy 

 beans were matured and separated into seed and straw. Soy beans continued 

 to respond to nitrogen fertilizers although by now the soil had become well 

 inoculated with their specific bacteria. Dr. Brooks states in his report for 1901: 



The development of nodules upon the roots of the crop this year was very abundant. Tn ppite 

 of this fact, . . . the crop on the no-nitrogen plots stands considerably below that on the other plots. 



