﻿A<;i;K'i:i.Tt l.'AI. UTILIZATION OF ACID LANDS. 6 



It is also well known to farmers that, after a few years" prelimi- 

 nary culture in vy<-\ potatoes, and buckwheat, virgin timberland with 

 its humus-laden soil of a century's accumulation from rotting leaves 

 and roots will sometimes produce heavy crops of timothy, wheal, and 

 clover for one or two generations. The success of these crops shows 

 that the soil has ceased to he acid. Again, when the store of humus 

 derived from the forest has linally been exhausted after long years 

 of ceaseless cropping, these soils revert to a condition of acidity, when 

 lime is regarded as necessary to further agricultural prosperity. 



What is this peculiarity of forest leaves by which they make the 

 soil at one time acid, at another alkaline? It is worth while to. con- 

 sider this question, for its answer will throw new light on the prac- 

 tice of agriculture. 



DECOMPOSITION OF LEAVES. 



A layer of freshly fallen leaves on bare ground, moistened by rain, 

 begins at once to decompose. A brown liquid leaches out of the 

 leaves into the underlying soil. This liquid is acid. If the soil itself 

 is naturally acid, its acidity is increased by these leachings. If the 

 soil is sand, neutral in chemical reaction, it is made acid by the 

 leachings from the leaves. But if the soil is alkaline from the 

 presence of carbonate of lime, as in the case of ordinary loam of 

 high fertility, the acidity of the leaf water is neutralized and its 

 brown matter is precipitated, forming a portion of the black humus 

 of the soil. On such an alkaline soil leaves decay rapidly from 

 beneath and form a black, mellow, and very fertile leaf mold in 

 which all traces of leaf structure have disappeared. Under such con- 

 ditions the layer of leaf litter is always thin, often not lasting 

 through the summer, and the transition from leaves to underlying 

 mold is abrupt. 



In sand, however, there is no such acid-neutralizing substance, and 

 both soil and leaves remain in an acid condition unfavorable to 

 complete decay. The next j^ear a fresh fall of leaves brings a new 

 accession of acidity, and the acid condition of the leaf litter becomes 

 permanent. In a sandy oak or pine woods there is thus built up a 

 tough mat of upland peat often several inches in thickness, com- 

 posed of half-rotted leaves interlaced with the rootlets of trees and 

 underbrush. Such peat mats are always acid, like ordinary bog peat. 



One might conclude from what has been said that leaves unless 

 treated with lime would remain acid throughout the process of 

 decomposition. Such a conclusion, however, would be erroneous. 

 Leaves when sufficiently decayed lose their acidity and of them- 

 selves produce a black mold that is not merely neutral in reaction, 

 but sometimes markedly alkaline. 



