FARM DRAINAGE. 



55 



5th. It enables us to work our lands much earlier in the 

 spring. 



6th. It prevents washing and waste of manure. 



7th. It prevents wheat and other winter grain from freez- 

 ing out. 



To these I would add that it prevents failure of crops in 

 excessively wet seasons, and enables them to endure drought 

 better. 



It also saves time, as the farmer whose lands are drained 

 can not only work them earlier in the spring, but also gain a 

 day or more after each heavy rain. 



How Drainage Helps the Soil. To understand how 

 drainage can accomplish all the points claimed above, some of 

 which seem to be incompatible with each other, it will be neces- 

 sary for us to consider some of the characteristics of the soil 

 and the conditions of successful plant growth. 



No soil can produce useful crops when it is permanently sat- 

 urated with water. Even the cultivated grasses will perish, and 

 nothing but reeds, rushes, and sedges grow. 



The best condition of soil for plant growth is that in which 

 the particles of soil are moist but with no standing water 

 between them. 



Our figures show the difference between dry, wet, and 

 drained soils as seen under a magni- 

 fying glass. A soil is made up of 

 small particles thrown together mis- 

 cellaneously, having small spaces be- 

 tween them, like a sponge. There are 

 also small pores and cells in the par- 

 ticles themselves. Fig. 1 shows a dry 

 soil, there being no moisture either 

 between the particles or in them, but 

 all the cavities filled with air alone. 



FIG. 1. DRY SOIL. 



As moisture is a prime essential for the growth of plants, it is 

 evident that the seed a can not germinate nor plants grow in a 

 soil in this condition. Fig. 2 shows a block of soil saturated with 

 water, and here both pores and cells are filled with water. In a 



