SOIL MANAGEMENT 



effective in absorbing and holding the moisture than are coarser 

 grained materials. When puddled by wet plowing or poor man- 

 agement the pores may become so small that water is held so 

 tenaciously that it is of little use to the crop. The following 

 table gives the proportion of pore space in some conmion classes 

 of soils : 



I 



I 



22X 



CBX 



LOAfii 



^OZ 



30X 



60X 



■A/S'y 



}.7^Ar£-f!i 



(//yA\^AJL^Bl € : 



■:/SO/L: 



f CLy^y ^ 



CRANULATEP PUDDLED 



2X 



esz\, 



70Z 



■\^i^Afef7--y 



■yt^Ai^A'LAau 



-SO/L'^r-- 



mm 



Fig. 1. — -Diagram representing the proportion of space occupied by soil material, 

 water, and air in a section of different soils. The availability of the soil water 

 and presence of sufficient air are dependent on the right physical conditions of 

 the soil. 



Pore Space in Soil 



. The importance of the right proportions of the soil constitu- 

 ents and their relation to texture and structure is shown in the 

 diagrams of Figure 2, which is taken from a Cornell reading 

 course bulletin. 



Soil moisture and crop production. — It is a matter of common 

 observation that crops make a much better growth in a moist 

 soil than in a soil that is too dry. The quantity of water used by 

 a growing crop is very large and varies considerably with dif- 



