measured at one inch above the ground surface, syn. Basal 

 cover, Ground cover, cf. Cover. 



Basal Cover 



See Basal area (2). 



Basal Metabolism 



The rate of physiological processes in an organism when 

 it is carrying on a minimum of its life processes such as 

 respiration in order to remain alive. 



Base Exchange Capacity 



A measure of the absorptive capacity of a soil for bases, 

 or exchangeable cations. A soil with a high base exchange 

 capacity will retain more plant nutrients and is less subject 

 to leaching than one with a low exchange capacity. 



Base Flow 



Stream flow originating from subterranean sources in 

 contrast to flow from surface run-off. 



Base Level 



The lowest level to which a land surface can be reduced 

 by streams; the permanent base level is the level of the sea. 



Base Number 



The Haploid (q. v.) number of chromosomes (as found 

 in sperms or eggs, gametes) in those species with the lowest 

 number in a Polyploid series, or sometimes postulated for 

 a species that is extinct or unknown. 



Base Saturation 



The proportion of the Base exchange capacity that is 

 saturated with metallic cations. 



Basin Irrigation 



A method of irrigation in which a level area is sur- 

 rounded by an earth ridge so that a shallow body of water 

 may accumulate prior to infiltration. 



44 



