IMPKOVEMENT OF THE SOIL 57 



a green manure, it is often best to apply lime to avoid 

 inducing an acid condition. On the other hand, the 

 overapplication of lime is sometimes very injurious. 

 As is said, it burns the life out of the soil by render- 

 ing the elements of fertility too quickly and com- 

 pletely soluble, so that they are leached out and lost. 

 Some soils, too, it renders more liable to crust and bake 

 after rains. Lime should never be applied unless there 

 is clear evidence that it is needed, and good judgment 

 will be required to determine how much to use, since 

 this Avill depend entirely on the actual condition of 

 the field to which it is to be applied. As a rule 

 when lime is needed, it is best to make one pretty 

 thorough application and then add no more for four 

 or five years rather than to add small dressings annu- 

 ally. It is best, too, to apply it as long as possible in 

 advance of planting the crop so that it may have 

 time to lose some of its caustic action and become 

 more thoroughly incorporated with the soil. Lime 

 is usually applied in the form of the hydroxide; that 

 is to say, as slacked lime. This is the best form in 

 which to use it where it is desired to quickly correct 

 acidity or for the mellowing of intractable clays. 

 For the permanent improvement of sandy lands, how- 

 ever, especially if used in large quantities, the car- 

 bonate in the form of finely ground limestone or shells 

 is safer and will give much more permanent results. 

 Lime, in the form of the sulphate or land plaster, is 

 often applied with good results, especially on clover. 

 It should always be remembered, however, that lime 

 applied in any form acts as an alterative or stimulant 

 and not as a true food, and that unless active measures 



