New York Agricultural Experiment Station. 65 



scarcely be grown with success unless a fair amount of lime carbonate 

 is present. On acid soils timothy hay and many other of the grasses 

 will respond generously to liming. Corn, oats, barley and wheat 

 themselves often will give returns from the direct application of 

 lime sufficient to pay for its use. Potatoes and nearly all garden 

 and truck crops demand a normal amount of lime carbonate for 

 their most profitable production. With fruit the tendency of lime 

 seems to be to check excessive wood growth and promote fruitful- 

 ness. A few eccentric plants, including the blueberry, cranberry, 

 serradella, and common sorrel are said to reach their best develop- 

 ment on acid soils. A slightly acid reaction of the soil probably 

 does not directly affect plant roots, but a neutral condition or one 

 bordering on an alkaline reaction is important to the welfare of 

 beneficial microorganisms and those processes which make for the 

 production of available plant food. 



CHEMISTRY OF LIMES. 



Not only natural raw ground limestone but also freshly-burned 

 and hydrated lime may be used for the purpose of supplying lime 

 to soils deficient in lime carbonate. Freshly-burned and hydrated 

 limes, however, rapidly change over to the carbonate form on being 

 applied to the soil; that is, they shortly become of the same composi- 

 tion as raw ground limestone, a process familiar to everyone in the 

 changes that lime mortar undergoes on standing. If ; t were not for 

 this fact neither of the caustic forms of lime could be us«d on the 

 soil, for as long as they exist in the caustic condition they are liable 

 to be injurious. 



For many farmers one of the most perplexing questions that has 

 arisen in connection with the whole problem of supplying the soil 

 with lime carbonate is what form of lime is best to use or what is 

 the relative value and efficiency of the different forms. When pure 

 calcium limestone (CaC0 3 ) is completely burned it loses 44 per ct. 

 of its weight, yet the resulting product, which is calcium oxide 

 (CaO) or quicklime, contains just as much actual lime as the original 

 limestone. It follows then that 56 pounds of pure quicklime is 

 equal to 100 pounds of pure limestone. The above weight of quick- 

 lime slaked with just the right amount of water forms 74 pounds 

 of hydrated lime, (Ca(OH) 2 ). When either of these compounds is 

 exposed to air for a long time it completely recovers the weight lost 

 in burning; thus " air slaked " lime is nearly the same as pulverized 

 limestone. Now limestone is never entirely pure; good grades may 

 contain as much as 5 per ct. of impurities, consisting chiefly of clay- 

 like material. On burning, these impurities do not lose in weight 

 like the rest of the stone, consequently burned lime will contain a 

 higher percentage of impurities than the stone from which it is 

 burned. Also, burned lime begins to take up weight again as soon 



