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WASHING OF LANDS MAY BE PREVENTED BY METHODS OF CULTIVATION 

 AND UNDERDRAINAGE. 



The depth and character of the tillage are very important factors in 

 the washing of lands. A field in a condition of fine tilth and ploughed 

 to a depth of 10 inches will hold 2 inches of rainfall and absorb it very 

 readily, and a soil in such a condition will suffer no surface washing 

 from any ordinary rainfall. Where it is possible, therefore, land which 

 is apt to wash should have the soil gradually deepened and be kept in 

 a fine state of tilth so as to increase the storage capacity for excessive 

 precipitations. This will not only save the surface from being washed 

 and gullied, tut it will also increase the store of moisture held by the 

 soil, which is of very great value in the time of drought. 



It is important also for this, as for other reasons, that the soil be 

 covered with vegetation as much as possible throughout the year, as the 

 roots and organic matter serve to bind the grains of the soil together. In 

 gome parts of Holland the drifting sands of the coast, which shift their 

 position with every storm, often cover up valuable farming lands. 

 Vast areas of these sands have been reclaimed and made productive by 

 being covered with vegetation, while the roots and remains of organic 

 matter hold the soil grains in place and prevent them from drifting and 

 covering up more valuable lands. Any crop which requires very clean 

 culture, as for example, cotton, is exhausting to the land for the reason 

 that constant exposure of the surface to the sun and storms uses up the 

 organic matter, makes the soil less porous, and the soil particles them- 

 selves are more easily washed away ; so that, this clean cultivation is 

 in its effects very favourable to excessive erosion. 



Another very effective method, when properly carried out, to prevent 

 the washing of lands is to underdrain the soil with tile or other 

 drains. These drains carry off quite rapidly an excess of moisture, so 

 that much more of the rainfall is absorbed by the soil and carried oft 

 through the drains and less washes over the surface of the land. Not 

 only this, but a well-underdrained field is usually dryer and more 

 porous, and has a greater capacity for absorbing the excessive rainfall 

 and thus preventing surface washing. A field thoroughly underdrained 

 with tile drains will carry off the water of any ordinary rainfall with- 

 out any surface erosion. This method is very effective, but is like- 

 wise very expensive, and can not be used economically in extensive 

 farming solely for this purpose of protecting the land from washing. 



While the land may thus be made more porous and more absorbent 

 of water — through the increase of the amount of organio matter or of 

 humus, through the use of lime and other fertilizing material, through 

 the deepening of the soil by gradually increasing the depth of culti- 

 vation, by so cropping it that it shall be covered with vegetation as 

 much of the year as possible, and by underdraining the land— still, 

 these methods may not be sufficient to so change the chemical and 

 physical texture of the soil as to enable it to absorb the rain as it falls 

 and to prevent an excess of water washing and eroding the surfaoe 

 where the contour of the land is such as to promote erosion from the 

 surface flow of the excess of water. 



It will be necessary in this case to provide for a more uniform dis- 

 tribution of the flow over the surface, and to prevent any accumula- 

 tion of water which would have the effect of a torrential stream. 



