1898.] PUBLIC DOCUMENT -No. 33. 19 



The unfavorable influence of the season and possible differ- 

 ences in natural fertility of the soil serve to obscure the 

 action of the phosphates employed. 



Leguminous Crops (Clover, Pea and Bean, or "Pod" 

 Family) as Nitrogen Gatherers. (Field A.) 



A full history of the field since 1884 is given by Dr. 

 Goessmann in our ninth annual report. The years 1884-88 

 were preparatory ; the experiment proper began in 1889. 

 The objects in view have been : — 



1. To determine the extent to which plants of the clover 

 family are capable of enriching the soil in nitrogen taken 

 by them from the air through the agency of the nodular 

 bacteria found upon their roots. 



2. To compare nitrate of soda, sulphate of ammonia, 

 dried blood and barn-yard manure as sources of nitrogen.* 



The field is divided into eleven J^ acre plots, numbered 

 from to 10. Three plots, 4, 7 and 9, have received no 

 application of nitrogen-containing manure or fertilizer since 

 1884. One (0) has received barn-yard manure ; two (1, 2), 

 nitrate of soda; three (5, 6, 8), sulphate of ammonia; and 

 two (3, 10), dried blood every year since 1889. These 

 materials have been used in such amounts as to furnish 

 nitrogen at the rate of 45 pounds per acre each year. All 

 the plots have received, yearly, equal amounts of phos- 

 phoric acid and potash. The quantities applied have fur- 

 nished, per acre, phosphoric acid 80 pounds, and potash 

 125 pounds, from 1889 to 1894 and the past season. In 

 1895 and 1896 double these quantities were used. Dr. 

 Goessmann reports : f — 



The total yield of crops on the plots receiving no nitrogen, as 

 compared with those receiving nitrogen, was in the several years 

 as follows : — 



With com in 1889, one-fifth less. 



With oats in 1890, one-fifth to one-sixth less. 



With rye in 1891, one-fifth to one-sixth less. 



With soya beans in 1892, one-third to one-fourth less. 



* Only such details are given here as are necessary to a general understanding of 

 the subject ; full information is found, as stated above, in our ninth annual report. 

 t Ninth annual report, Hatch Experiment Station, page 175. 



