4 8 SCIENTIFIC AGRICULTURE. 



of intelligent men. If a soil has all the constituents 

 that plants need, and in the best possible condition 

 for use as plant-food, then such soil cannot be im- 

 proved. If, however, one or more constituents are 

 deficient, or entirely absent, or not in the best con- 

 dition to serve as plant-food, then improvement is 

 not only possible, but desirable. 



103. The means used for the improvement of 

 soils are : 



Mechanical, as draining, plowing, sub-soiling, 

 mixing with clay, etc. 



Chemical, as manuring or fertilizing. 



The first changes the physical properties; the 

 second, the composition. When necessary constitu- 

 ents are absent or deficient, no amount of draining 

 or sub-soiling will secure a good crop. 



104. The extensive and thorough system of drain- 

 ing by means of tiles or clay pipes, which is used 

 in Europe and in some portions of our own country, 

 is too costly where land is cheap and abundant. In 

 such cases open ditches should be used to carry off 

 surplus water. Intelligent farmers understand very 

 well the importance of removing excess of water by 

 some sort of drainage that will be least likely to re- 

 move the soil with it, but unfortunately they do not 

 always put their knowledge into practice. Where 

 loose rock is convenient, covered ditches with ten or 

 twelve inches of rock at the bottom are easily made, 

 and form excellent drains. Deep plowing and sub- 

 soiling are means of draining, to a limited extent, 



