1917.] PUBLIC DOCUMENT — No. 31. 31a 



continued with few exceptions throughout a long series of years. 

 Reference will be here made to a few results only, which seem 

 to be so fully established as the result of long-continued work 

 that there can be little question as to the reliability of the con- 

 clusions which will be stated. 



Fertilizers in Addition to Manure for Market-garden Crops. — 

 Long-continued experiments in the use of different combinations 

 of high-grade chemicals in connection with manure at the rate 

 of 30 tons per acre applied annually indicate that the employ- 

 ment of fertilizers with such an amount of manure on the soil 

 on which the experiments have been tried — a silt loam with 

 excellent physicial characteristics — has not resulted in increas- 

 ing the crops to such an extent as to cover the cost of the 

 materials used; indeed, with the majority of crops and in the 

 majority of seasons there has been no appreciable increase. 

 Notwithstanding the facts just stated, the experiments which 

 have been so planned as to make comparisons between three of 

 the most prominent materials which can be purchased as a 

 source of fertilizer nitrogen — nitrate of soda, dried blood and 

 sulfate of ammonia — have indicated the first to be the best 

 source of nitrogen, and that sulfate of ammonia unless used in 

 connection with liberal applications of lime may prove abso- 

 lutely injurious. 



Comparison of Different Phosphates. — This is a long-time 

 experiment for the purpose of determining the relative value of 

 the different materials found in our markets which may be used 

 as a source of phosphoric acid. This investigation has been in 

 progress for twenty years. Results were fully reported and 

 conclusions on all important phases of the inquiry presented in 

 Bulletin No. 162, which can still be obtained on application. 

 This bulletin was prepared at the end of the eighteenth year; 

 1916 was the twentieth year. The results of the past year 

 with corn tended still further to strengthen the conclusion that 

 dissolved or acid phosphates are much preferable under the 

 conditions of our agriculture to the fine-ground natural rock 

 phosphates. 



Methods of applying Manure. — Two methods of applying 

 manure, namely, spreading direct on the field when hauled from 

 the pits, at various times during the winter, and placing in a 



