FERTILIZERS. 763 



perchlorate was evident witliin a few weeks after the beginning of the 

 experiments, altbough no such effect was observed where no nitrate or 

 only pure nitrates were used. The maximum amount of perchlorate 

 wliicli can be applied to rye without injurious effect was not determined, 

 but this is to be made the subject of further investigation. 



Experiments Avith soluble, reverted, and insoluble phosphoric 

 acid, E. 11. Hkss {rcnii,sj/lr<(iiia Sf<(. lipt. ISn'j, i)p. ir)7-:JJ(>). — This is a 

 continuation of experiments carried on since 1883 on 12 twentieth-acre 

 phats (E, S. K., 3, p. 4G1). They ''were made ui)on the ordinary four- 

 course rotation of this section, viz, wheat, grass, corn, and oats, the fer- 

 tilizers being applied to the wheat and corn, and were preceded by an 

 unmanured oat crop upon all the plats in 1883 for the purpose of testing 

 the uniformity of the soil." 



The results are tabulated in detail and may be summarized as follows: 



" Tr/(e«/.— Taking the average for the 3 years, 1884, 1888, and 1892, insoluble phos- 

 phoric acid in tlie lorni of ground hone, was first in the yield of grain and straw, 

 insoluble phosphoric acid in the form of ground South Carolina rock second in grain 

 and straw, uo phosphoric acid third in giain and fifth in straw, reverted phosphoric 

 acid in the form of dissolved boneblack treated with an equal weight of lime fourth 

 in grain and third in straw, and soluble phosphoric acid in the form of dissolved 

 boneblack iifth in grain and fourth in straw. 



"(IroHs. — Taking the average for the 3 years, 1885, 1889, and 1893, inscduble phos- 

 phoric acid (ground bone) was first, reverted second, soluble third, and insoluble 

 (South Carolina rock) fourth. 



"Cum. — Taking the average for the 3 years, 1886, 1890, and 1894, insoluble phos- 

 phoric acid (ground l)one) was first in the yield of grain and stover, reverted second 

 in grain and third in stover, soluble third in grain and second in stover, and insolu- 

 ble (South Carolina rock) fourth in grain and stover. 



" Oats. — Taking the average for the 3 years, 1887, 1891, and 1895, insoluble phos- 

 phoric acid (ground bone) was first in the yield of grain and straw and weight i)er 

 bushel, insoluble (South Carolina rock) second in grain and straw and fourth in 

 weight per bushel, reverted third in grain, fourth in straV, and second in weight 

 per bushel, no phosphoric acid fourth in grain and fifth in straw and weight per 

 bushel, soluble fifth in grain and third in straw and weight per bushel.'' 



The conclusions reached are as follows: 



"(1) Soluble phosphoric acid is too expensive to be used by farmers having a lime- 

 stone soil similar to the one on which this experiment was made, since fully as good 

 results can be secured by the use of the much cheaper insoluble form. 



"(2) Insoluble i)hosphoric acid in the form of ground bone is slightly superior to 

 that in the form of South Carolina rock. 



"(3) Corn is benefited more by the application of phosphoric acid than wheat, 

 oats, or grass.' 



Experiments on the effectiveness of citrate-soluble phosphoric 

 acid in Thomas slag, M. Maercker {Jahrh. a<ir. vhem. Virs. Stat. 

 Ilallf^ JS.'fo, 2>p- 24-30). — Thomas slags containing different amounts of 

 citrate soluble phosphoric acid were compared with water-soluble phos- 

 phoric acid on alfalfa and oats, followed by white mustard grown on 

 sandy soil in ])ots. The results (;learly indicate that the citrate solu- 

 bility is a true index of the effectiveness of the phosphoric at;id of the 

 slag. 



looOL'— No. 3 



