SOIL MOISTURE AND PREPARATION OF S(ML. (i7 



center of the box, a lui slowly pour water into it, until the 

 soil at the bottom of the box is moist, as determined by 

 removing the cork, and thrusting a rod, or straw, into 

 the hole. 



(e) Now, beginning at each side of the trench, remove 

 a layer of the soil three inches in depth, noting carefully 

 just how far the water has extended from the trench by 

 lateral capillary action. 



FIG. 20. APPARATUS FOR EXPERIMENT I3. 



(/) Remove another layer of soil three inches in 

 depth, and note the lateral extension of the water at this 

 depth. 



(g) Remove a third layer three inches in depth, and 

 note again. Compare the lateral extension of the water 

 at each of these depths with that of the other two. 



It Is upon this principle of lateral capillary 

 action that irrigation is based. 



III. Preparation of the Seed-bed. 



I. Ploiuing'x's, done before planting- (i) to de- 

 stroy weeds by completely covering them ; (2) 

 to bring plant-food to the surface ; (3) to pul- 

 verize and aerate the soil ; and (4) to allow the 



