67 



The most important thing in the recovery of waste fields is the 

 incorporation of organic matter of some kind in the soil ; pea vines, 

 stubble, briers, or leaves from the forest may be used as a source of the 

 organic matter. The straw from one acre of land which has been recov- 

 ered, as mentioned above, will be sufficient to start the recoverv of 

 another acre, even if this be deeply furrowed with gullies. Where 

 enough organic matter can be used as a surface dressing, this layer 

 helps greatly to retain water and to make the underlying soil more 

 absorbent. 



As soon as a sufficient supply of humus has been accumulated 

 and the lands are brought up to an adequate condition of fertility, 

 clover or grass should be seeded, if the land is at all suited to these 

 crops, or rye, oats, or field peas should be sown to help hold the sur- 

 face. Little by little, but more rapidly than would be expected from 

 the forbidding aspect of the field, the land can be reclaimed again and 

 made productive through the accumulation of humus and organic mat- 

 ter. A soil containing a fair quantity of humus will wash less readily 

 than one nearly destitute of this matter. 



A soil containing a fair supply of lime is much less liable to wash 

 than one similarly situated and exposed which is deficient in lime. 

 The reason of this is that clays which are deficient in lime, when once 

 brought into suspension by moving waters, will remain in suspension 

 and keep the water turbid far a long time. Clays which are heavily 

 impregnated with lime salts, on the other hand, are in a flocculated 

 state, the fine grains of clay being held together and in contact with 

 the larger grains of sand. This flocculated mass quickly settles and is 

 originally not so easily disturbed and carried off by moving water. A 

 field treated with an abundance of lime is thus less easily washed by 

 heavy rains. The results of investigations by Schulze, Schloesing, and 

 Hilgard have shown in a most emphatic way the beneficial changes 

 which take place, especially in stiff clay soils, by the application of 

 lime. 



The change in the 'physical condition of the soil which is produced 

 by the lime, and which is likewise produced by a number of other 

 chemicals ordinarily used in commercial fertilizers, is another impor- 

 tant factor worthy of consideration. A stiff clay soil is practically 

 impervious to the penetration of surface water when it is delivered in 

 such torrents as we are liable to have in our summer storms. A well- 

 limed soil, on the contrary, although it may contain as much clay but 

 in which the particles are flocculated or drawn together, is much more 

 pervious to water, and the amount of water which the soil will carry 

 down through underdrainage is increased, and the excess which has 

 to flow off over the surface is diminished. The surface washing of cul- 

 tivated fields, especially those which are naturally deficient in lime, 

 can be greatly diminished, therefore, by the free application of this 

 substance to them. 



A number of the ordinary fertilizing materials have an important 

 effect upon the texture of soils and upon the permeability of soils to 

 water, but few systematic investigations have been carried on in this 

 line and not much, except of local importance, has been definitely set- 

 tled by experiments or by the experiences of farmers. 



