STUDIES ON THE LIME REQUIREMENTS OF 

 CERTAIN SOILS. 



By henry brougham HUTCHINSON 

 AxND KENNETH MacLENNAN 



(Carnegie Research Fellow). 

 (Laives Agricultural Trust, Rotiianisted Expenmenial Station.) 



(With Plate I and 4 text-figures.) . 



The fertility of a soil may be stated to depend on two functions, 

 namely, its capacity to supply the necessary nutrients for plant growth, 

 either by virtue of original reserves or by biological action, and its 

 suitability as a matrix, serving to hold plant roots and possessing definite 

 relations to air, water and temperature ; these determine very largely 

 the amount of growth attained by any crop. Since, however, the 

 growth of soil organisms as well as that of any introduced plants is 

 very sensitive to the reaction of the matrix, it follows that cases may 

 arise in which the jH'esence or absence of a base would definitely set 

 a hmit on crop production. 



The compounds commonly used to correct soil reaction in the 

 field are those of calcium — either as oxide, hydroxide, or carbonate, as 

 in chalk, limestone, or marl; the benefits accruing from their use are 

 well recognised, but the difference in their type of action has not hitherto 

 received the attention it deserves. 



In two earher communications it has been shown that caustic hme 

 exercises a specific effect on the soil, producing when apphed in sufficient 

 quantity certain effects common to those which have been classed under 

 the head of " partial sterihsation." Calcium carbonate does not exercise 

 this action, but either form may be used for correcting soil reaction. 

 In practice this difference has not been recognised and has been 

 responsible in many instances for the misinterpretation of experimental 

 work, since it is difficult to determine precisely how far any result has 

 been due to neutralisation or to sterihsation effects. 



