98 AGRICULTURE. 



and tested for acid w'th blue litmus paper. If need be, 

 leave the litmus paper covered in the soil over night. 



(d) If any soils turn the litmus paper red, the class 

 should visit that particular place, or places, where the 

 acid soils were found, and study the vegetation, making 

 a list of the plants found growing there, and examine 

 the conditions, to discover, if possible, the cause of the 

 acidity. Is the drainage good ? The ventilation ? Is 

 the place densely shaded ? What is the texture of the 

 soil ? Is it a humous, loamy, clayey, or sandy soil ? 

 Could the conditions be improved ? How ? 



(e) Collect a sufficient quantity to fill several small 

 pots with this soil, and try to grow some plant which is 

 averse to acid soil — as, clover, lettuce, or timothy. To 

 one pot add lime in small but definite quantities, thor- 

 oughly mix, and let stand for a few days. Test again 

 with litmus; if still acid, add lime until the litmus is no 

 longer affected, and then try to grow the same kind of a 

 plant as in the pot of acid soil, starting them both at 

 the same time and keeping them under similar condi- 

 tions. 



(/) Compare the growth made by the two plants, and 

 record your observations and conclusions. 



Not only does lime sometimes prove benefi- 

 cial to plant growth, but it is also beneficial to 

 the development of the nitrifying bacteria of the 

 soil, which for some reason thrive best in a 

 mildly alkaline soil (see " Clover Sick Soil.") 

 Lime and wood ashes aid nitrification by fur- 

 nishing calcium and potassium to unite with the 

 nitric acid formed by the bacteria. Lime is also 

 helpful in keeping in check certain injurious in- 

 sects and fungi, though the potato scab (a fun- 



