CHAPTER 3 



TREATMENT OF SICK SOILS 



Our conception of a healthy soil as has been in- 

 dicated is one which is ideally suited to plant growth, 

 through proper physical and chemical make-up, and 

 by the presence of groups of beneficial micro-organ- 

 isms. A sick soil is one in which plants would grow 

 very languidly or not at all. Soil sickness may be 

 caused through the improper use of fertilizers, or 

 through the introduction of parasitic disease-produc- 

 ing organisms. 



Acid-Sick Soils 



Soils which contain an excess of acid, in which 

 crops refuse to grow, may be termed acid-sick. Acids 

 in soils have a directly poisonous eflFect on plants. 

 Soil acidity may be brought about by the loss of lime 

 and of other bases; and by the decomposition of 

 organic and of inorganic matter. 



Crops are known to draw heavily on the lime 

 of the soil, and thus to increase the proportion of 

 acidity. This, then, is one direct way of depleting 

 the soil lime. Lime and other bases are further 

 lost from the soil by leaching. The soluble car- 

 bonates are but slowly soluble in pure water. How- 

 ever, carbon dioxide, nearly always present in soils, 



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