Investigations at Burlington, Colorado. 



73 



loam at Burlington is underlaid at about 2.5 feet with hardpan, while powdery- 

 loess occurs below this level. All of the soils are very fertile, their physical 

 effect upon the water-content affecting crop production to ajfar greater degree 

 than their chemical composition. 



August 



Fig. 33. — Average daily soil-temperature at Lincoln (solid line), Phil- 

 lipsburg (long broken linea), and Burlington (short broken 

 lines), 1920. 



August 



Fig. 34. — Average daily air-temperature at Lincoln (solid line), Phil- 

 lipsburg (long broken lines), and Burlington (short broken 

 lines), 1920. 



A study of the water-content to a depth of 4 feet shows that at both the 

 upland and lowland stations at Lincoln at least 7 per cent (and usually 10 

 to 20 per cent) available watei was present at all depths below 6 inches until 

 the middle of July. At no time during the growing-season was the supply 

 of available water, even in the surface 6 inches, entirely exhausted, a margin 

 of 4 to 9 per cent being maintained in the deeper soil even during the driest 

 part of the season. At Phillipsbuig the water relations were less favorable. 



