SOIL SURVEY OF THE RED BLUFF AREA, CALIFORiSTIA. 31 



general surface is not level, being marked by minor drainage ways 

 through the main bodies and slightly dissected at terrace lines. The 

 type at the seasons of greatest rainfall suffers from poor drainage. 

 Over almost the entire surface occur small minor depressions without 

 outlet, oftentimes giving the appearance of a hog-wallow topog- 

 raphy. With a heavy burden of surface water completely saturating 

 the soil and filling the small depressions, this condition is still further 

 aggravated by a j^uddling tendency of the soil and the impervious 

 nature of the subsoil. Altogether it is a somewhat difficult soil to 

 handle extensively in grain farming. 



In origin this soil type is more recent than the Redding and Corn- 

 ing series, as is evidenced by their relative positions and occurrences, 

 small knolls and ridges of both series sometimes lying within the 

 areas of the Tehama silt loam as remnants of the older series. 



An instance of this may be observed south of Redbanlv Creek be- 

 tween the main line of the Southern Pacific Railroad and the Corn- 

 ing road running south from Red Bluff. In this case an isolated 

 area of Redding loam, representing an undisturbed body of the Red 

 Bluff formation, was entirely surrounded by soils of more recent 

 formation. 



The Tehama silt loam is not normally underlain by hardpan, but 

 in a very few instances hardpan and cemented layers common to 

 other nearby types may lie within 6 feet of the surface. 



When grain production was at its height this type was nearly all 

 utilized and returned profitable yields despite its puddled and poorly 

 drained conditions before mentioned. The type has suffered de- 

 creased yields in common with all the plains and upland types until 

 at this time it is not extensively farmed. A paying crop of grain 

 can be secured about every third or fourth year by summer fallowing, 

 if favorable moisture conditions prevail. In this uncommon case a 

 minimum rainfall is most favorable. 



The more extensive utilization of this type depends entirely on 

 irrigation. It is not adapted to fruit, berry, or alfalfa culture under 

 dry-farming methods, and while partial success may be attained on 

 the better areas, little can be done upon those large typical areas, 

 such as that surrounding Rawson. This type, as mapped, can be 

 relied upon to yield good returns under irrigation, and, consider- 

 ing its area, will contribute to the success of anj^ large irrigation 

 enterprise supplying water at even more than average cost. The 

 features which now render the soil hard to handle in grain, namely, 

 poor drainage and baking, will not be found to retard its irrigation 

 developments materially. A slight leveling of the surface and the 

 formation of a few drains to carry off surface water can be accom- 

 plished in small tracts and at a slight expense. This would not, 

 however, be justified by its returns as a grain soil. 



