Factors affecting available ooil moisture: 



1) Precipitation 



2) Catchment \ 



3) 'ater holding capacity of soil 

 4} Evaporation from soil 



5 | ter withdrawn by plant roots 



Ability of soil to raise water by capillarity ana other 

 mo ..s. Jlei^ht of water- table. 



7) ifridergrourid seepage 



1) Precipitation is affected, by go. r *r?.T)h.lcpl loo-r-tion and topo- 

 phy. 



2} Cat&runent /< isa i. of all precipitation Actually entering 

 ,/il. It depends on; 

 . Joii cover. 



b) Degree of slope. ' ivr^ter slope hfl or; runoff and there 

 fore a email e r c ... ; , 



c) Texture of soil. 



d) Character of precipitation. 4= 



Auio un t 



Mature ( sudden, fant, or glow) 

 e; Character of ^ro'ind surface 



plowed, baked, dusty, etc . 



3, r holding capacity of soils. 



-ilia depends on texture, depth, nd amount of or^ajde Batter 

 '.' s soil, 



texture may be considered in two parts: 

 a) Physical composition: si^e of particles. 

 Consistency of soi"' . : 

 _i density of particle arrangement 

 iT structure of soil 



i locculent, simple, compound, etc. 



Floccuiency decreases the water holding capacity of soil 

 it increases tlie air spaces; the resulting ventilation is the desirable 

 feature of flccculent Boil, especially in clay. Clay is the cementing 



it oi the particles and crumbs in clf?y and loam; calcareous material 

 in sand protases tiie snm^ effect. 



occurs 



pillary water/, in smaller Dre spaces or oft<-;n as forming a film 

 about hygroscopic water, the films clinging to particles. Capillary wa- 

 ter is available to plant roots; hygroscopic water usually is not. 



or hydrostatic water occurs in the larger pores in the upper 

 oo 1 . It sooner or later gravitates toward the water- t".l>le. In an imper- 

 vious layer is present above the water table the WRtsr gathers just 

 ove this layer. 



Hygroscopic water; film digging to particles. 



Hydrostatic water: free or gravitional water moving down to the 

 water* table. 



Water holding capacity of soil is effected by pore upace 'tmd the 

 size of soil particles. The arrangement of particles affects the pore 

 space (s e page 107). ^0 s^ize. of the particles theoretically has no 

 effect on pore apace. 3aft& Small particles really tend sornev/}iat to more 



