142 Fertilizers 



Chemical effects of lime. 



Roots of peanuts exude small quantities of acid during 

 growth, and likewise organic matter during decomposi- 

 tion gives off acids. This is really a provision of nature 

 because the acids produced in this manner aid in making 

 the soil stores of mineral plant-food available, but an ac- 

 cumulation of these acids which is bound to follow is 

 sure to give rise to compounds poisonous and harmful to 

 vegetable life. Lime has long been used to neutralize 

 these so-called soil acids, and this chemical effect is un- 

 doubtedly the best known of all the advantages derived 

 from the use of lime. To correct acidity, or sweeten 

 sour soils, is a function of lime thoroughly appreciated and 

 well understood. This practice also kills many of the 

 lower forms of plant life which flourish on sour soils and 

 allows the more nutritive plants to grow. 



Lime supplies a necessary base. 



Soils that contain insufficient basic compounds such as 

 carbonates of calcium, magnesium, potassium and sodium, 

 are not in a condition to produce maximum crops. The 

 absence of such compounds permits the accumulation of 

 acids. Under such conditions normal decomposition of 

 organic matter, the formation of nitrate nitrogen from 

 ammonia, and organic matter, and the utilization of at- 

 mospheric nitrogen by bacterial activity are severely 

 hindered. While the correction of acidity and the addi- 

 tion of lime as a basic-compound are more or less analo- 

 gous, it is thought best to mention the latter to point out 

 the fact that the addition of just enough lime to correct 

 acidity may not be sufficient to promote chemical and 

 bacteriological functions. (See Figs. 11 and 12, Plate VII.) 



