IO4 SOILS 



unless they are able to combine with other substances 

 that eliminate or render impotent this acid effect. We 

 have a number of substances that can be used to correct 

 this acidity, among which may be mentioned lime and 

 wood ashes. Both of these substances are good, but lime 

 is usually the cheapest, the most available and easiest to 

 apply ; hence, its use as a corrective for acidity is most 

 often mentioned. Soils most likely to be found sour are : 

 heavy clay soils, when poorly drained; soils abundantly 

 supplied with organic matter ; soils that have been poorly 

 tilled, and consequently air-hungered ; and soils deficient 

 in humus but kept at work by mineral substances, like 

 kainit, muriate of potash, and acid phosphate. When lime 

 is applied to soils of such nature, its wholesome influence 

 is manifest at once. In this connection the beneficial in- 

 fluence of lime on the availability of nitrogen is of inter- 

 est. It has been shown by Wheeler at the Rhode Island 

 Station that lime exerts a direct benefit to plant growth 

 by overcoming soil acidity, and in doing so, increases the 

 assimilability of the soil nitrogen. Hence, we have an 

 improvement of the physical condition of the soil and 

 also an increase in availability of plant nutrition. 



How acidity may be detected. Does your soil look sad 

 and sickly? If so, it may need lime. Does your soil fail 

 to produce vigorous growth and good color in the plants 

 it grows? If so, it probably needs lime. Does your soil 

 show acidity when tested? If so, it truly needs lime. 



Suppose you try this method for detecting acidity : Get 

 a penny's worth of blue litmus paper at the drug store. 

 Dig from the field a handful of wet earth that looks sus- 

 picious ; into this insert your knife blade, and in the open- 

 ing put a strip of the blue litmus paper, and press the soil 

 tightly about it. If sour, in a short time the paper, where 

 in contact with the moist soil, will become reddish in 



