WHAT THE SOIL SUPPLIES 313 



is laborious, and fertilizers are often used as short cuts to 

 save labor. 



The breaking up of the soil for planting seeds is known 

 to every one, but its purpose is not so widely understood. 

 Many suppose that it is only a way of getting seeds into the 

 ground, but that is the least important of its purposes. Its 

 real purpose is to pulverize the soil, because finely pulverized 

 soil is in the best physical condition for plants. In the first 

 place, it secures a good circulation of air, which we have 

 learned is essential for the best plant growth. In the second 

 place, it enables the soil to hold a much larger amount of 

 moisture. Strange as it may seem at first thought, the 

 smaller the soil particles and the closer together they are, 

 the more water will the soil hold. This is explained by the 

 fact that the amount of water held by the particles is approxi- 

 mately in proportion to the surface they present, and of 

 course there is much more surface presented by very numer- 

 ous small particles in a given space than by less numerous 

 large particles. The capacity of a soil for water, therefore, 

 is in proportion to the minuteness of its particles. This com- 

 bination of small particles and free circulation of air is an 

 ideal combination for productive soil. Of course, pulverizing 

 the soil also improves its drainage, and so permits unimpeded 

 circulation of air. 



The ideal physical condition of the soil is attained in the 

 potting of plants, in which the soil is pulverized and screened, 

 but this degree of tillage is not practicable when large areas 

 are concerned. And still it shows that the more persistent 

 and painstaking the tillage, the better the results in crops. 



After the soil is well tilled, and the seeds are sown, the work 

 of tillage is not at an end. The physical conditions that favor 

 germinating seeds also favor growing plants; therefore the 

 soil must be kept in good physical condition. An additional 

 advantage of tillage to growing plants must be mentioned, 

 and that is the conservation of moisture. Water not only 



