7 

 furnishes an active base for the formation of the resulting nitrate salt. Liming 

 is very favorable to bacteria found in the nodules on roots of various leguminous* 

 plants. The presence of a liberal amount of lime in soils is unfavorable to 

 certain parasitic organisms vi^hich cause club root of cabbage and a similar 

 trouble with turnips known as finger and toe disease. Although lime decreases 

 the tendency to these diseases, it favors the development of scabby fungus of 

 potatoes and black root rot of tobacco, and should be used with great care and 

 in moderate quantities on soils that will be devoted to these crops. 



The more active forms of lime will improve the physical condition of heavy 

 clay soils, making them more open and porous and thus easier of tilth. 



Lime Recommendations. 



It is a relatively simple matter to determine the lime absorption capacity of 

 a given soil by any one of the laboratory methods. It is equally simple to esti- 

 mate the hydrogen ion concentration or pH value of soils by any one of the 

 colorimetric methods or by direct reading with the potentiometer which meas- 

 ures the electrical resistance of the soil solution. It is an entirely different 

 matter, however, to make exact recommendations as to lime applications based 

 upon results secured. In fact, there are so many varying factors which enter 

 into the problem that at best we can only offer suggestions which may apply to 

 the majority of medium to fine sand and silt loams. 



It should be borne in mind that the amount of lime to be applied to any given 

 soil must vary according to the crop grown, the type of soil, and the character 

 of lime i^roduct used. Sufficient data may never be accumulated to cover all con- 

 ditions, and the grower must to a considerable degree make his own interpreta- 

 tion. The following table has been prepared as a rough guide in liming soils on 

 the basis of their hydrogen ion concentration or pH value only. 



A hydrogen ion concentration (pH) of 7 denotes a neutral reaction, being 

 neither acid nor alkaline; above 7, an alkaline condition. With average Massa- 

 chusetts soils, therefore, reactions such as these (and they are few in number) 

 indicate that the use of lime is unnecessary. A pH below 7 denotes acidity; and 

 the stronger the acid reacting matter in the soil, the lower becomes the reading, 

 and the more lime is needed to correct the condition. A pH of 4 or less indicates 

 an exceptional concentration of acid reacting medium and usually calls for a 

 relatively heavy lime application for most crops and soils. A reaction ranging 

 between 4 and 5 would be called very acid ; between 5 and 6, moderately acid ; 

 and between 6 and 7, slightly acid. 



