124 MASS. EXPERIMENT STATION BULLETIN 176. 



found in the extracts from any Rhode Island sample, but was obtained 

 from all the Ohio samples. Iron was extracted from aU but the more 

 heavily limed soils. 



Table IV. — Milligrams of Aluminium Oxide {AUO3), Iron Oxide {Fe^O^, 

 and Manganese Oxide {Mn^O^^ removed in Water from 100 Grams of 

 Soil. 



[Soils representing Ohio and Rhode Island experiments with ammonium sulfate.] 



^'-^r I™- Oxide. Ma^nganese 



Ohio plot 8, limed, 

 Ohio plot 8, unhmed, 

 Ohio plot 24, limed, 

 Ohio plot 24, unlimed, 

 Rhode Island plot 23, 

 Rhode Island plot 25, 

 Rhode Island plot 29, 



The Ohio soil which had received sulfate of ammonia (plot 24) without 

 lime gave a striking reaction for soluble manganese salts similar to our 

 own soils; but in the soils from Rhode Island the sulfate of ammonia 

 seemed to exert its influence on aluminium and iron compounds (plot 23). 



At a later period samples of soil were received from Prof. F. D. Gardner 

 of Pennsylvania State College, which were taken from different plots on 

 the permanent experiment field at that institution. The soil of the field 

 is a clay loam. The samples were taken from plots 31, 32 and 36. 



Plots 31 and 32 had received equal amounts of dissolved boneblack and 

 muriate of potash. Plot 31 had sulfate of ammonia appUed at the rate 

 of 240 pounds per acre every two years, while plot 32 received 360 pounds 

 per acre in the same period. Plot 36 received no fertilizer. This treat- 

 ment had been in vogue since 1885. 



One kilogram of air-dry soil was treated with water by the percolation 

 method. 



Plot 32 with the heavier application of ammonium sulfate jdelded strik- 

 ingly more iron and a little more manganese than plot 31. 



The unfertilized soil, plot 36, yielded the most iron, but a negligible 

 amount of manganese. 



