402 REPORT OF THE COMMISSIONERS OF 



of roots and humus is also active in sand. Although silica is an obstinate substance 

 it is slowly corroded and comminuted by the action of vegetal matter, so that even 

 sand soil, under the action of the forest, is rendered physically, as well as chemically, 

 better. The most important point in this connection, however, is the fact that forests 

 bring the rich materials from the deeper layers of the soil and deposit these in the 

 form of litter on the surface. 



Immense quantities of this surface material are wasting every day through the 

 action of fire. Upon this material the lasting fertility of the soil depends. Upon the 

 fertility of the soil the perpetuity of the forest depends; and perpetuity is the keynote 

 of forestry. The removal of litter from a soil which is already rich is like stealing a 

 small sum of money from a very rich man; the removal of litter from hungry sandy 

 soil is like stealing bread from a starving beggar. On this question of humus volumes 

 have been written. Half of all the troubles of European foresters are due to the per- 

 sistency with which the peasant clings to the old communal right to remove the litter 

 for manure. In times of poor crops the German Government permits the collection of 

 humus from state torests by the peasants. A load of well-rotted leaf-mould is equal 

 in fertility to a load of barnyard manure. 



Of course there are many kinds of humus, some of which are of little value for 

 manure. Peat and swamp muck, for instance, are sour and only partly decomposed. 

 Good humus is never formed in regions which are too dry, too cold or too wet. Good 

 humus is never formed in direct sunlight. It needs shade, sufficient moisture, warmth, 

 oxygen, and a host of animals and fungi, which aid in the process of aeration and 

 fermentation. Humus or leaf-mould is a great storehouse of nitrogen and other 

 plant-food, and an efficient mulch or blanket for the protection of the soil and the 

 conservation of moisture. By means of it the soil is protected from the destructive 

 drying action of sun and wind, and from the beating and leaching action of rain. It 

 increases the capillarity of the soil. It fills up the interstices of the soil with rich, 

 spongy, juicy matter, and thus obviates the main objection to a sandy soil, which is 

 its coarseness. By means of it imbibation by capillarity of the water from below is 

 possible. Humus, then, is not only the great storehouse of plant-food, but the place in 

 which it is being constantly produced. It is not only a sponge which holds water, 

 but a blanket which prevents excessive evaporation, and which sucks up the water 

 which would otherwise slip away. 



The formation of leaf-mould is something more than mere oxidation. Hundreds of 

 fungi and bacteria are concerned in the process. In addition, the animals of the soil, 

 especially the earthworm, play a very important role. These industrious creatures not 

 only aerate the soil by the channels which they form, but actually eat it, extracting 

 from it what they may need, and casting out the rest in the form of a rich, friable soil. 



