ACTION OF LIME 595 



lime which has been used for the purification of illuminating gas 

 made from coal, is hardly to be considered in this connection, 

 since it may contain very little even of the hydrate. In this case 

 the lime has been converted largely into carbonate and sulfid. 



500. Application of Lime. For many reasons it is important 

 that the lime be transported to the field before it has had time to 

 be converted into hydrate. The transportation costs less in this 

 state and it can be handled with far less inconvenience than when 

 slaked. The lime should be placed in small piles and left thus, 

 best covered with a little earth, until thoroughly slaked. It is 

 then spread evenly over the surface. The quantity used per acre 

 depends largely on the nature of the soil. Stiff clays and sour 

 marsh lands require a larger dressing than loams or well aerated 

 soils. From three to six thousand pounds per acre are the quan- 

 tities usually employed. When the lime is once thoroughly incor- 

 porated in the soil it is rapidly converted into carbonate, but while 

 n the caustic state it may act vigorously in promoting the decay 

 of organic matter and may prove injurious in promoting the de- 

 composition of ammonium salts with attendant loss of nitrogen. 



501. Action of Lime. The benefits arising from the applica- 

 tion of lime to agricultural lands, although in many cases great, 

 do not arise from any distinct fertilizing action of its own. Plants 

 need lime for growth and need plenty of it, but, as a rule, any soil 

 which is good enough to grow crops w r ill contain enough lime 

 to furnish that constituent of the crops for many years. Its ac- 

 tion is both mechanical and chemical. By virtue of the latter 

 property it renders available for plant food bodies already existing 

 in the soil, but existing in such shape as to be unavailable for 

 plants. The supply of plant food available for the crops of one 

 year is increased, but this increase is at the expense of the follow 

 ing years. Lime is a stimulant. Theie is a common proverb 

 that "lime enriches the father but beggars the son." Never- 

 theless, a limestone country is usually a fertile one and soils con- 

 taining plenty of lime naturally, are nearly always rich soils. It 

 is said that the trees and plants which farmers pick out as indic- 

 ative of rich land are nearly always those which prefer lime 

 soils. 



