500 STATE BOARD OF AGRICULTURE. 



Pennsylvania Agricultural Experiment Station in Table III. In these 

 studies equal quantities of a given soil were treated with the same 

 amount of magnesian and non-ma gnesian limestones, the particles of 

 which ranged in size from coarse to very fine. xVfter a period of three 

 years the comparative rate of change, or tlic elticioiicy of these in meet- 

 ing the soil's requirement was ascertained by chciuical means. Accord- 

 ing to these results if the particles are very fine the dift'ereuce in the 

 rate of transformation is negligible. 



TABLE ///.—COMPARATIVE KATE OP TRANSFOKMATION OF LlxMESTONE IN THE 



SOIL. 



Per cent, of total carbonates not recovered after three years. 



Non-magnesium Magnesium 



Limestone. Limestone. 



100 mesh limestone 92.4 91.2 



60 mesh limestone SI . 5 72.2 



20 mesh limestone 46.7 34.9 



S mash limestone 14.9 5.97 



If the lime is not mixed with the soil mass, of course, its efficiency is 

 somewhat impaired. Inasmuch as the individual particles of marl are 

 very minute its immediate effectiveness is governed larg(3ly by the condi- 

 tion in which it goes into the soil. If lumpy, naturally larger quantities 

 are required to bring about a given result tlian if it is more or less 

 disintegrated. As it usually goes on the land, about 214 to o cubic 

 yards of 95% marl are required to equal 1,500 pounds of the hydrate 

 and 2,000 pounds of the powdered limestone respectively. This ratio 

 decreases the second year inasmuch as the lumps are broken down by 

 freezing and changes in the water content. 



CROPS BENEFITED KY LIME. 



The response of our cultivated plants to lime is variable some being 

 more tolerant of a deficiency in the soil than others. Reports on record 

 sliow that some crops will thrive on a given soil witliout application 

 of lime and others will not, while some soils are so low in lime that 

 they are practically barren of plant growth. Thus, in discussing the 

 response of different crops to lime it is essential tliat tlie condition of 

 the soil with respect to this substance be considered. Some of the field 

 crops that are known to respond to lime are as foUovv's: 



