Monce: Quarry Industnj of Southern Indiana 133 



In other words, calcium oxide (quicklime) plus nitric acid equals 

 water and calcium nitrate. 



CaCOs + 2HNO3 = H2O + CO2 + Ca(N03)2* 



This means that calcium carbonate (crushed limestone) plus 

 nitric acid equals water, carbon dioxide gas, and calcium nitrate, 

 the same compound that came from the caustic lime. The 

 function of soil conditioning already mentioned is performed 

 equally well by both, but they differ in their effect upon the 

 organic matter present in the soil. Caustic lime is better than 

 ground limestone only when the soil contains an abundance of 

 organic matter or some form of phosphorus which is not readily 

 available. It should always be borne in mind that caustic lime, 

 altho giving good results for a year or two, tends in the end to 

 impoverish the soil. 



Probably no more convincing experiments have been carried 

 on along the line of the relative values of burned lime and crushed 

 limestone than those of the Pennsylvania and Maryland Experi- 

 ment Stations. The results of these experiments are summarized 

 in University of Illinois Experiment Station Circular No. 110, 

 p. 6, as follows: 



Four plots were treated with burned lime (slaked before being spread) 

 at the rate of 2 tons per acre once in 4 years. Four other plots were treated 

 with ground limestone at the rate of 2 tons per acre every 2 years. A 4-year 

 rotation was practiced consisting of corn, oats, wheat, and hay, the ha^/ 

 being mixed timothy and clover, seeded on the wheat land in the spring. 



Seven products were obtained and weighed each year: namely, 

 corn, corn stover, oats, oat straw, wheat, wheat straw, and hay. 



After 20 years results had been obtained (1882-1901). . . showing 

 that with every product a greater total yield had been obtained from the 

 plots treated with limestone than from those treated with burned lime. 



Furthermore, with every product whose total yields for the last 

 8 years was greater than for the first 8 years the limestone produced a greater 

 increase than the burned lime; and with every product whose total yield for 

 the last 8 years was less than the total yield for the first 8 years, the decrease 

 was less where limestone was used. . . . This . . . demon- 

 strates the tendency of burned lime to exhaust or destroy the fertility of the 

 soil. 



The actual figures of the above experiments are, to say the 

 least, startling, and the effect upon the soil shown by careful 

 chemical analysis bears out the statements already made. The 

 nitrogen present in the soil treated with crushed limestone 



*It is not meant to imply that soil acidity is really due to nitric acid. 



