INFLUENCE OF WATER 19 



In illustration C the water has reached the bottom of 

 the cloddy portion. The uneven edge shows that where 

 the soil particles are compact the water climbs upward, 

 thus illustrating an important characteristic of capil- 

 larity. Too many air spaces in the cloddy ground 

 break up the capillarity so that water will not climb as 

 rapidly or as effectively and abundantly as it does in 

 soil finely compacted. Two hours were required for 

 the water to rise from the bottom of the tube to the 

 cloddy portion. 



Illustration D is the same tube photographed 22 hours 

 later. Observe that the soil is thoroughly permeated 

 with water up to the cloddy portion, that the moisture 

 in the cloddy part and the pulverized part above the 

 clods is very slight, and that on top no moisture is to be 

 discerned. This shows that moisture does not rise to 

 the surface of the ground any faster than it is evaporated. 

 If this tube contained a plant above the cloddy part it 

 would be plainly evident that the amount of moisture 

 the roots could secure would not be enough to promote 

 the healthy growth of the plant. Therefore, it is very 

 important that this cloddy condition does not exist at 

 the bottom of the seed bed as much on account of 

 moisture as heat and air. 



Film water displays itself only upon the surface of the 

 soil grain. That is why it is called film water. It 

 forms a film around the grain. Anyone can easily 

 satisfy himself as to the truth of this, by taking a 

 marble and immersing it in a glass of water, then with- 

 drawing it. All the water required to form the film will 

 cling to the marble and the rest will drop off. Suppose 

 that marble is one inch in diameter. It will fill a cube 

 one inch square that is, six points on the surface of the 



