186 



Physics of the Soil. 



stirred. Soils which maintain a strong capillary rise of 

 water through them will, when converted into mulches, 

 still permit the water to waste through their mulches faster 

 than it will be lost through the mulches of soils which 

 permit only slow capillary movements. That is, the sandy 

 soils form more effective mulches than do the clayey ones 

 and this greater effectiveness of the sandy soils, as mulches, 

 goes a long way toward making the smaller amount of 

 water they are able to retain effective in crop production. 

 In Fig. 58 is shown an apparatus for measuring the 

 relative effectiveness of mulches and in the table which 

 follows are given the results of a series of trials with 

 three types of soil. The cylinders in this series, however, 

 stood out in the open air of the field rather than in the 

 case shown in the cut 



Table showing the effectiveness of soil mulches of different 

 kinds and different thicknesses. 



From this table it will be seen that the soil mulches have 

 exerted a very great influence in saving soil moisture. 



