BULLETIN OF THE 



crue on the whole soil capital. Should be the guidinj 

 principle in all cases. 

 Order of rotation can be determined by analysis of crops 



MODIFICATION OF SOILS BY ARTIFICIAL MEANS. 

 By mechanical operations. 



Tillage secures looseness, easy penetration of roots, cii 



culation of air, soil-gases and water. 

 How nature tills mulching, frost, wetting and dryii 

 Artificial condition of culture; overriding of natural ac 



aptations of soils and localities. Hence necessity fo] 



tillage, preparation and cultivation. 

 Importance of depth of soil for equalization of extreme] 



and safety of crops. 

 Depth of soil equivalent to cultivating larger areas, bu| 



with less labor and greater safety of crops. 

 In shallow soils, crops are at the mercy of seasons. 

 Heavy soils need thorough tillage most. 



Deep tillage sub-soiling. 

 Chemical and physical differences between soil and sub] 



soil. 

 Stirring versus turning up conditions under which eithej 



may be useful or injurious. 

 Treatment of subsoiled lands, for maintenance of profit] 



able productiveness. 

 Subsoiling not a preventive of exhaustion. 



Drainage Under draining. 

 "Believes wet soils:" but does a great deal more us( 



ful in all soils. 

 General plan of underdrains. Various methods, tilt 



drains, log-drains, brush-drains, etc. 

 Mode of action, difficulties and remedies. 

 Action of underdrains on clay soils. Analogy to subsoil^ 



ing; protection against drouth by deepening of soil. 

 Drained lands can be tilled at all times; are less cold; less 



liable to surface washing. 

 Advantages to public health. 

 By addition of Material (a.) "Mechanical Manures." 



Not often profitable by themselves should be combined 



with other objects. 

 Management of natural drainage to effect desirable 



changes. 



192 



