LIMi:^ GYPSUM AND GRKKN MANURUS I05 



organisms cannot work to advantage in an acid niodiuin. 'JMicre 

 may be an ample supply of nitrogen, phosphoric acid and potash 

 in a sour soil and yet good crops cannot be produced because of 

 the need of lime. Soils that run as low as 0.2 per cent, of calcium 

 carbonate generally need lime. 



How to Find Out "When Soils are Acid. — A simple method that 

 is often effective consists of testing the soil with blue litmus 

 paper. A few cents worth of this paper may be purchased at a 

 drug store. Test the soil as follows : Collect some earth from 

 those portions of the field where the plants are poor or sickly. 

 JNIix the samples of earth together, take a small portion and add 

 water to form a paste. Place one end of the litmus paper in this 

 mixture and let it remain for about 45 minutes. If the soil is 

 sufificiently acid the color of that part of the litmus paper which 

 was dipped in the paste will be changed to red. This is not a 

 delicate test and is only an indication of a soil badly in need of 

 lime. Another way to find out whether your soil needs lime is to 

 express about one-half a pound of the suspicious soil to your 

 State Experiment Station requesting them to find out if your 

 soil needs lime. Or a plot of the suspicious land may be spread 

 with a liberal application of lime and the efifect on the crop noted. 

 This last method is perhaps the best test. 



How to Apply Lime. — Finely ground limestone, quick lime, or 

 water slaked lime may be used to correct acidity in soils. If 

 water slaked lime is used it should be applied just as soon as it 

 becomes powdered. If quicklime is preferred, it may be dumped 

 into small heaps and kept covered with earth until the lime slakes 

 or crumbles. 



Lime should be spread in a thin even layer and harrowed in. 

 If slaked lime is used it should be harrowed in immediately as it 

 changes to the carbonate form on exposure to the air. Some 

 farmers use a lime spreader which machine is very effective. 

 Lime should be applied some time before planting as it is liable 

 to injure the seed. 



The Form of Lime to Use.— Marble dust, ground limestone, 

 ground oyster shells, etc. (calcium carbonate), are preferable 



