234 Bulletin 254. 



acter or intensity of these essential conditions. They must have food, 

 moisture, heat, hght and air and they must be mechanically supported in a 

 congenial manner. All of these conditions, except the light, are modified 

 in some way by the soil which is simply a medium for the supply of the 

 essential factors of growth. Anything which modifies these in a way un- 

 favorable to a particular plant hinders the development of that plant. 



Practically all of the crops grown in New York are land plants and are 

 adapted to growing in a moist soil and not in a wet soil. Herein they differ 

 from water plants. Therefore, they will not grow normally in a saturated 

 soil. A saturated soil is one which has all its pores filled with water. In 

 such a soil if the water is free to flow out under the influence of gravity, 

 part of it will pass away. But a large part of such moisture — from 40 to 

 70 per cent — will be retained by the soil. The soil holds it, causing a film 

 to overspread all of the particles and to fill the smallest spaces. This 

 moisture which is retained is called capillary water and is the form suited to 

 the use of ordinary crops. It can only be lost by evaporation. It gives 

 the soil a nicely moist appearance. It produces the condition of wetness 

 for which the farmer should strive. The retention by any cause of any 

 part of the soil water, which woulfl flow away if free to do so, is directly 

 injurious to ordinary growing crops in proportion to its amount. Drain- 

 age is the process of removing this undesirable excess. It must be re- 

 moved before tillage can be properly practiced and before that congenial 

 and sanitary environment, desired by all our common crops, can be obtained. 



New York State has a very large area of farm land on which the 

 drainage should be improved and it is not confined to the areas of an 

 acknowledged swamp or marsh condition,. It includes even larger areas 

 now laid out in fields and regularly cultivated to crops. 



I. TYPES OF DRAINAGE. 



There are two general types of drainage, (i) Open or surface drains, 

 consisting of any sort of depression in which water will accumulate and 

 through which it will flow. In these there is a great range in efficiency de- 

 pending on their mode of construction, the soil conditions and their state 

 of repair. (2) Closed or sub-surface drains, composed of any available 

 porous stratum through which the water will flow more rapidly than 

 through the natural soil. Nature often constructs such subterranean 

 drains of strata of sand, gravel or limestone directly beneath the low or 

 impervious stratum. Man constructs similar porous strata of stone, wood, 

 tile or any other available material. Of these materials, the tile drains are 

 most efficient and are the ones with which this bulletin is primarily con- 

 cerned. 



