COMMERCIAL FERTILIZERS 65 



the soil more acid, while nitrate of soda, carbonate of 

 potash and Thomas phosphate tend to make the soil alka- 

 line. In the brands of fertilizers most used in this sec- 

 tion, the acid-forming ingredients largely predominate. 



"One of the most important factors contributing to 

 malnutrition is the exhaustion of the organic material in 

 the soil. Fields where this disease occurs are found to 

 contain only 1.65 per cent organic matter, while normally 

 3 to s per cent should be present. 



"This deficiency is to be expected from such complete 

 dependence on commercial fertilizers, which cannot take 

 the place of stable manures and green manures in a per- 

 manent system of agriculture. 



"Remedial and preventive measures recommended for 

 malnutrition diseases are: (i) Limitation of the amounts 

 of fertilizer used; (2) adjustment of the composition of 

 the fertilizer to suit the crop requirements; (3) the ra- 

 tional use of lime; (4) the maintenance of the organic 

 matter of the soil." 



no. The use of lime. — ^The necessity of lime has been 

 indicated in previous paragraphs. Malnutrition disease 

 may become serious when lime is not used or when soils 

 become acid. In vegetable gardening it is important to 

 keep soils slightly alkaline and this is best accomplished 

 by the rational use of lime. Va. Truck Expt. Sta. Bui. 

 4, p. 80 : "Experiments on Norfolk soils show that liming 

 is very beneficial to all crops except peas, beans and 

 tomatoes. On cabbage lime was added in the spring of 

 1909, just before planting, and the yield was greatly in- 

 creased thereby. The succeeding year the experiment 

 was extended to include other crops, and the yield of all 

 crops except peas and beans was markedly increased." 



Lime not only neutralizes soil acidity, thus providing 

 favorable conditions for friendly micro-organisms, but it 

 also improves the physical character of soils, promotes 

 decomposition, makes plant food available and enters into 



