SOILS AND FERTILIZERS 507 



77; Ariz. E. S. B. 45; Colo. Ag. Col. Bs. 99, 178, 179; Mass. E. S. B. 

 50; Calif. Col. B. 7; F. B. 315; Bu. Pit. Ind. Bs. 63, 71, 76; Univ. 

 Minn. B. 34; R. I. Col. B. 147; Mich. Ag. Col. B. 231; Kans. Ag. 

 Col. B. 160 ;0. E. S. B. 54. 



LIMING OF SOILS. 



Ruffin is perhaps the most prominent of the earlier writers who 

 called attention to the agricultural use of lime in the United States. 

 As early as 1818, and later, in 1821, articles on the subject were con- 

 tributed by him to the American Farmer, and in 1832 appeared the 

 first edition of his well-known work on Calcareous manures. He 

 cites many instances showing the benefit derived from calcium car- 

 bonate when applied in the form of marl to his own and other Vir- 

 ginia estates. 



In certain parts of Pennsylvania and New York lime has long 

 been considered one of the essentials in wheat production. The 

 beneficial effect of liming has been demonstrated in Alabama, Alaska, 

 New Hampshire, Massachusetts, New York, Virginia, Maryland, 

 Pennsylvania, Oregon, Illinois, and other parts of the United States, 

 but, as Roberts states, probably 99 per cent of the arable soil of the 

 United States has never been limed, and indeed many large areas 

 are not in need of it. The work of the experiment stations, stimu- 

 lated at the outset by that of Rhode Island, has now shown con- 

 clusively that soils which respond profitably to liming, either on ac- 

 count of their acid condition or of a deficiency of lime in other 

 respects, are very widely distributed. 



Direct Manurial Action of Lime. Authorities seem to agree 

 that lime is necessary to the plant, and if it be wholly lacking in 

 soils, even though an abundance of all the other essential elements 

 is present, the plant can not develop normally. The plant can not 

 grow if any one of the essential elements of plant food is lacking. 

 As already stated, lime has been found to be especially deficient in 

 soils derived from granite. It is also often true of soils derived from 

 mica-schist, sandstone, and from certain conglomerates, slates, and 

 shales. Fortunately, however, many soils are well provided with 

 lime by nature and it is seldom or never necessary for those who 

 cultivate them to resort to liming. It would be just as irrational to 

 apply lime where it is not needed as to omit it where it is required, 

 and hence arises the necessity of ascertaining the needs of particular 

 soils in this respect. 



The method usually resorted to for ascertaining the amount of 

 lime in soils is to treat them with some strong mineral acid (usually 

 hydro-chloric) and determine the amount of lime which is thus dis- 

 solved. Some writers state that if only one-half of 1 per cent is thus 

 shown to be present immediate resort to liming is desirable; others 

 set the amount higher, and some seem to prefer to have present as 

 much as 1 per cent. It is possible that a soil may contain consid- 

 erable quantities of lime thus removable by acid and yet in actual 

 practice show much benefit from liming. As a matter of fact, soils 

 of limestone origin sometimes show benefit from liming because 

 sufficient carbonate of lime is not present in the soil. 



