Breast Height 



A height of 4.5 feet (1.3 meters) above the average ground 

 surface or above the root collar, diameters of standing trees 

 are ordinarily measured at this height. (Abbreviation is 

 d. b. h.). 



Breccia 



A rock composed of angular pieces in a matrix. 



Breeding (Plants, Animals) 



The application of genetics and other sciences in the 

 systematic improvement of a Taxon or a population. 



Breeding Potential 



See Reproductive potential. 



Broad-base Terrace 



A terrace 10 to 20 inches high, 15 to 30 feet wide, with 

 gently sloping sides, a rounded crown, and a dish-shaped 

 channel on the upper side, built to divert run-off water along 

 the contour. 



Broadcast Seeding 



Scattering seed on the surface of the soil as contrasted to 

 seeding with a drill in rows. cf. Drill seeding. 



Brown Forest Soils 



A group of soils with dark brown surface horizons, rela- 

 tively rich in humus, becoming lighter colored below, 

 slightly acid or neutral, with moderate amount of exchange- 

 able calcium; commonly developed under deciduous forests 

 that are relatively rich in bases, particularly calcium. 



Brown Podzolic Soils 



A group of soils with thin mats of partly decayed leaves 

 above a thin, grayish brown layer containing mineral matter 

 and humus; overlying yellow or yellowish brown acid B 

 horizons; developed under deciduous or mixed deciduous- 

 coniferous forests in cool temperate, humid regions. 



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