No. 6. 



DEPARTMENT OP AGRICULTURE. 



171 



The objects of tillage are: First, to increase the water-holding 

 power of the soil, so that more will run in and less will run otf 

 or drain out. Second, to admit air freel}^ to all parts of the soil, so 

 that the bacteria of the soil may develop and thrive, and carry on 

 the work of tearing down the organic matter, and prepare it for 

 food for the plant, and to facilitate th?i dissolving of the mineral 

 elements. Third, to make it easier for the fibrous rootlets to thread 

 their way through the soil and get in contact with the water films 

 in which the food is held in solution. Fourth, to prevent growth of 

 weeds and loss of moisture after heavy rains by prompt tillage, 

 two to two and a half inches deep. 



The poorer a soil is in vegetable matter or humus, the less water 

 it will hold, and the quicker it will lose what it does retain. 



The adding of manure, and especially the turning under of catch 

 crops (legumes preferred) will increase the water-holding power, 

 and it will suiter much less loss by evaporation, because the top 

 inch will dry out without crusting or baking, forming a jiartial dry 

 earth mulch. The richer soil is more drouth resistant, and suffers 

 less from lack of tillage, when prompt tilla.ge cannot be given. 



LIMING THE SOIL. 



Figure 7 is a reproduction of the clay particles floating in a drop 

 of water, showing how they repel one another and keep separate. 

 Figure S shows the same sample, with a little lime water added. 

 Note how the lime acts on the clay particles to draw them together 

 in clusters, so that each little mass acts toward water and air 

 together as one soil grain. This flocculation by the action of lime 



Fig. 7. 



Fig. S. 



gives clay soils a more porous and loamy character, and points out 

 one way in which lime benefits the soil physicallj', if used in mod- 

 eration, and in the presence of organic matter. 



