16 



MASS. EXPERIMENT STATION BULLETIN 195. 



Table III. — Tobacco Soils arranged in Groups according to " Lime Re- 

 quirement," with General Notes on Crop Conditio?}. 



The results given in this table apparently indicate that tobacco is 

 making a better growth on soils which are rather more "acid" than we 

 have been in the habit of believing to be best for tobacco. As a matter 

 of fact, the soils which show the least acidity are those which have had in 

 the past large and more or less consistent applications of lime, or those 

 which have been planted to tobacco for a long period of time. Whether 

 or not these soUs which seem to be so "acid" actually are, is an open 

 question. In all the methods of acidity determination used, we measure 

 the amount of acidity and not the intensity, and it is being found that 

 a determination of the concentration of the hydrogen ion gives us, often, 

 different results.^ These results are important, and bring before us the 

 question of lime (for we reduce the acidity of our soils by liming or by 

 certain systems of fertilization) and its use on tobacco soils. Do they 

 indicate that we have been liming too much, and that if we keep off 

 lime entirely for a time we will eradicate much of the trouble? This 

 cannot be stated absolutely as a general proposition in the light of work 

 carried on so far, but it can be positively stated that we have found 

 many instances where lime, especially in active form, has been applied to 

 soUs with the result that in from two to three years the crop has been 

 reduced considerably. This is particularly noticeable where lime has 

 been dumped and then later spread. The areas on which the lime was 

 dumped became very unproductive, and we are therefore justified in 

 stating that it would be advisable to withhold hme from fields which 

 have been in tobacco for some time, especially from lighter soils where 

 the supply of organic matter is small. Apropos of the advisability of 

 adding lime to tobacco soils, especially light soils, it should be noted that 



1 A study of the hydrogen ion concentration in our tobacco soils is in progress and nearing 

 completion. This study is to include a comparison of results obtained by this method with 

 those of the present report, and a discussion of the practical interpretation of the same. This 

 paper, which will of necessity be more or less technical in character, will be published separately. 



