Section III, 1921 [65] . Tfaxs. R.S.C. 



Notes on the Nature of Burn-outs 



By Frank T. Shutt, D.Sc, and Alice H. Burwash, B.A. 



(Read May Meeting, 1921) 



The prairie surface of certain areas in the western provinces, and 

 more particularly in Southern Alberta and South-Western Saskat- 

 chewan, is characterized by irregular but roughly circular depressions 

 or eroded spots varying from 3 to 6 inches in depth and from a few 

 inches to several or many feet in diameter. These depressions, 

 pockets or eroded spots are commonly known as "burn-outs". They 

 may be few or many in a given area ; in the latter case the praii î takes 

 on a peculiar pitted or pock-marked appearance. When these burn- 

 outs are numerous or large they may leave^ — presuming they are 

 eroded areas — but a small percentage of the original unaffected virgin 

 surface soil and the question then arises, how will such an area, when 

 put under cultivation, compare in respect to fertility with land broken 

 from similar prairie but free from burn-outs? ^ From their occurrence 

 and appearance there seems little doubt but that burn-outs are spots 

 that have lost, from one reason or another, the fertile surface soil, and 

 this assumption is borne out by the fact that they carry no vegetation 

 save cacti, in districts in which the surrounding prairie is well grassed. 

 The soil of a burn-out for the first few inches is usually extremely 

 hard and so impervious that after water has been standing on the 

 spot for several days the soil beneath the first few inches is still hard 

 and dry. After breaking for cultivation this burn-out soil apparently 

 becomes as pervious as the soil or subsoil of the adjacent area. 



To settle this question as to the nature of burn-outs is a matter 

 of some considerable agricultural importance. While it is true that 

 the marked difference prevailing in humid districts between surface 

 soil and subsoil, in respect to nature and fertility, is not as apparent 

 in soils under semi-arid conditions, yet it is obvious that if an area 

 has lost, say 50 per cent of its surface soils rich in humus and nitrogen 

 — ^the distinguishing features of a fertile loam — it must, for some years 

 after "breaking," be inferior as compared with an adjacent area free 

 from burn-outs. 



The burn-out selected for this investigation, and which may be 

 considered typical, is situated a few hundred feet north of the Govern- 



4t has been estimated that in Southern Saskatchewan alone there are 652,800 

 acres so affected. (" Problems of the Burn-out District of Southern Saskatchewan.") 

 J. Stanfield, Trans. Roy. Soc. of Canada, 1919. Field engineers who have made 

 surveys in both provinces state that the affected area of Southern Alberta is very 

 much larger than that of Southern Saskatchewan. 



