496 STATE BOARD OF AGRICULTURE. 



is kuowii as quick lime, burnt lime, stone liuie, caustic lime, lump lime, 

 unslaked lime and building lime. The liydrated lime also is called slaked 

 lime. The carbonate is the form of lime found in ground limestone and 

 marl and also occurs in air slaked lime. 



The term ''agricultural lime" may be applied to any of the above 

 forms and refers to lime sold for agricultural purposes but unfortunately 

 not necessarily to a product especially well adapted for application to 

 the soil. 



When high grade limestone is burned in a kiln, 100 pounds of the 

 dry stone gives oil approximately 44 pounds of carbon dioxide gns, leav- 

 ing about 56 pounds of lime oxide or quick liuje. When 50 pounds of 

 quick lime is moistened it takes up 18 pounds oC water and forms 74 

 pounds of slaked lime or hydrated lime. It is evident then that 56 

 pounds of quick lime, 74 pounds of hydrated lime and 100 pounds of 

 limestone or lime carbonate have the same power to satisfy the needs 

 of the soil. However, some of these forms are niucli more soluble than 

 others and consequently react with tJie soil much more quickly and in 

 consequence we do not use these materials in these proportions in the 

 field. 



SOURCES OV LTAIR. 



Michigan is fortunate in possessing two inexhaustible sources of lime, 

 her limestone deposits and juarl beds. 



Limestone. At present there are in the State nbout forty-seven lime- 

 stone quarries. The majority of these are located in tlic Upper Penin- 

 sula and northern part of the lower peninsula. Tliere is a group of 

 quarries in the extreme southeastern part of the State and an occasional 

 quarry is found along the eastern coast and at othiM' points throughout 

 the commonwealtli. 



These quarries produce stone for a great variety of ))urposes, oiily a 

 small portion of their output being used in agriculture. Some of tlie 

 quarries turn out only a coarsely ground rock containing small amounts 

 of fine material, while others furnish a very finely ground high grade 

 rock. The limestone from the Michigan quarries are quite variable in 

 composition some containing 96 to 97 per cent of calcium carbonate 

 with only a trace of magnesium carbonate, while otliers carry as much 

 as 44 or 45 per cent of magnesium carbonate. 



Marl. There occur thoughout the State many beds of marl varying 

 from low to very high grade. The lime is present in the marl as carbo- 

 nate and hence supplies calcium to the soil in the same form as ground 

 limestone. In addition to lime carbonate some marls contain varying 

 amounts of magnesium carbonate, which also meets tlic ''lime require- 

 ment" of the soil. The value of marl then, depends on the amount of 

 calcium and magnesium carbonates it contains. A marl carrying 90 

 percent or more of these carbonates is considered to be of very high 

 grade. 



Occurrence of Marl. Marl is frequently found underlying areas of muck 

 and peat and also along the shores and in rhe beds of lakes. In some 

 instances the marl is covered by a few inches of muck while iu others 



