THE 1RRIGA TION A GE. 1 55 



fertilizes the ground. Scrape aside this upper covering and you will 

 find the soil underneath moist even in a dry time. This is one reason 

 why the destruction of the forest leads to aridity of the soil. Not long 

 since I read an article in which the writer spoke of the costly lesson 

 Mexico learned regarding the destruction of her forests and deplored 

 the fact that the people of the United States seemed indisposed to profit 

 by her example, but preferred to learn in that dearest of all schools 

 experience. 



Moisture in large quantities is necessary to the life of the plant and 

 it is also necessary to the soil in order that the plant food may be ren- 

 dered available, for the roots can only absorb soluble food. Pew, if any, 

 soils are so destitute of fertility that they can not support vegetable life 

 if the mineral plant food contained in them is rendered soluble for the 

 plant's use. It is this principle that transforms the desert into a garden 

 when water is applied, the minerals in the soil becoming soluble. 



There are many portions of the United States where irrigation is 

 not necessary, provided the moisture is conserved, and even with irri- 

 gation conservation is an equally good plan. There are seven ways by 

 which this may be accomplished, according to experiments tried at one 

 of the experiment stations, and the first and most important is by plow- 

 ing and cultivating. Not the surface plowing so much in favor among 

 farmers, but the kind that buries the sod and any refuse that may be on 

 the surface and pulverizes the soil into minute particles, which being 

 thus broken up, absorb a much greater amount of moisture from rains 

 than would be the case if the ground remained hard and lumpy. After 

 plowing the next resort is to the harrow and cultivator, which should be 

 used frequently. The roller is of advantage on certain soils; those, for 

 example which are loose and sandy or gravelly, as they need something 

 to render them more compact, for if too loose and porous the rain drains 

 right off. 



Mulching also serves to conserve the moisture, as we see in the 

 forest where the leaves act as a mulch, but this is not a practical method 

 on the open fields of the farm, where no trees shelter them from the 

 sun's rays. Then, too, sufficient herbage for this purpose would be hard 

 to obtain, so this method is of little practical value. 



Underdrainage is very important in this respect. Only the free 

 water that comes to the surface is removed by the underdrain, thus 

 leaving the upper part porous and ready to absorb the next rain, while 

 the surplus water is carried through a drain to a reservoir for use in dry 

 times. 



The influence of the wind in drying out the soil is well known and 

 may be lessened by building hedges to act as wind breaks, which serve 

 to protect the fields to some extent in winter and break the force of the 

 winds in summer. 



The humus or black soil caused by the decay of vegetable and animal 

 matter is a great storehouse for moisture and nitrogen. This humus is 



