402 SOILS 



lime will be found powdered and may then be 

 spread. If air-slaked lime is used, the applications 

 should be heavier. If lime is used in seeding to 

 grass, apply it ten to fourteen days before seeding, 

 if possible. It is not usually necessary to lime 

 soils oftener than once in four or five years. 



OTHER AMENDMENTS 



Land plaster, or gypsum, which is sulphate of 

 lime, has about the same effect upon the soil as 

 common lime. Gypsum was formerly used very 

 largely, especially on clover, Indian corn, and pota- 

 toes. It has been observed to increase the yield 

 of clover 20 to 30 per cent. ; but after a number of 

 years, this benefit is no longer obtained. Its 

 beneficial effect is due largely to the fact that it 

 makes the potash in the soil more soluble, thus 

 causing an increase in the crop. Land plaster is 

 not now used to any extent except as it occurs as 

 a part of acid phosphate, but in this case it has no 

 value for sweetening the soil. It can be used to 



freat advantage, however, on the floors of cow and 

 orse stables and the roosts of hen houses to pre- 

 vent the escape of ammonia. It is also useful, in 

 some cases, for treating alkali soils. 



Wood ashes are about 35 per cent, lime, and im- 

 prove the soil in all the ways that lime does. Part 

 of the excellent results commonly secured from 

 the use of wood ashes is due to the value of the 

 ashes for correcting acidity and setting free plant 

 food. 



Marl, which is chiefly fossil shells, contains 

 much carbonate of lime and is valuable for dressing 

 land that needs lime. Large areas of land in New 

 Jersey that were formerly unproductive have been 



