138 BOARD OF AGRICULTURE. [Pub. Doc. 



ammonia, supplemented by applications of nitrate of soda 

 made after growth had begun. A moderate application of 

 lime as carbonate was also made in each case, in conse- 

 quence of the fact that the soil was so deficient in this sub- 

 stance as to fail to produce peas, potatoes and oats, though 

 still yielding rye and lupines. Considering the character 

 of the soil, the moderate application of lime and the use of 

 kainite and sulfate of ammonia, which would tend to aggra- 

 vate the existing conditions, it is not improbable that the 

 lime of the phosphate itself may have been as important a 

 factor in helping the soil as the phosphoric acid. Deherain, 

 speaking of acid soils, calls attention to the fact that the 

 acids may combine with the lime of phosphates, thus re- 

 ducing their acidity, and rendering the phosphates more 

 assimilable. The reduction in the acidity would be a 

 potent factor in favoring the growth of many cultivated 

 plants, — a fact abundantly demonstrated in the experi- 

 ments at the Rhode Island station. It is probable, then, 

 in Kiihn's experiments, that some of the benefit attributed 

 by him to the phosphoric acid may have l)een due to the 

 lime of the phosphate. It must at all events be evident 

 that the benefit to be expected from bone, even upon light 

 ^nd sandy soils, will vary with the chemical character of 

 the soil itself. The greater the acidity, the greater will 

 probably be the benefit observed from the phosphate 

 applied. 



Experiments with diff*erent phosphates which have been 

 in progress at the Rhode Island station since 1894 bear 

 upon this question. The plots are all manured alike, so 

 far as concerns potash and nitrogen. One series was 

 treated with air-slacked lime in 1894 at the rate of one ton 

 per acre, none having been applied since. The total 

 amount of phosphoric acid applied in the period has l)een 

 the same upon each plot in both series. In the unlimed 

 series the total yield per acre for the four years' hay crop 

 (1896 to 1899 inclusive) was 1,295 pounds greater, where 

 fine-ground steamed bone was used, than where floats 

 (finely ground unacidulated rock) were employed. In the 

 limed series the difference amounted to 1,488 pounds. A 

 large application of nitrogen in the form of nitrate of soda 



