Land ChaTaaenstic3 



CLusl 



aast2 



Class 3 



Moist bulk dcnsirv^ 



Slopc» 



Drainage 

 Class 



Surface 



Subsurface 



1.30 g/ cm' CO 1.60 g/cm' 

 with overlapping of 

 blocks then allowable 

 densities would be less 

 than 1.55 g/cm\ 



0-4% 



Well and moderately well 

 drained, water table 

 below 60 inches 



Litde or no surface 

 drainage required. 



Wyi aerated, no limit to 

 moisture movement or root 

 developmenL 



Barrier (soil and/or drainage fiiaor)' 



Overflow (Flooding)" 

 Growing season'^ 



None in summer. Rare in 

 fall and winter. 



More than 105 days. 



Maximum allowable 1.60 

 g/cm' with overlapping of 

 blocks then allowable 

 densities would be less 

 than 1.55 g/cm'. 



4-6% 



Moderately well though 

 somewhat pworly drained, 

 water table below 36 inches. 



Shalbw surface drainage 

 required. 



Well to moderately well 

 aerated; moisture 

 movement and root 

 development somewhat 

 impeded. 



Rare in summer. Occasional 

 in fall, winter, and spring. 



90 to 105 days. 



Maximum allowable 1 .60 

 g/cm', with overlapping 

 of blocks then allowable 

 densities would be less 

 than 1.55 g/cm'. 



6 - 8% Gravity 

 15%Spnnkicr 



Somewhat excessively 



through poorly drained, 

 water table below 18 inches. 



Shallow surface drainage 

 required. Occassional 

 small depressions, shallow 

 drainwavs, few complex slopes. 



Moderately wdl aerated, 

 moisture movement, and 

 root development 

 moderatclv rcstriaed. 



I 



Occassional in summer. Frequent 

 in fall, winter, and spring. 



Less than 90 day growing 

 season, oops produced 7 

 out of 1 vears. 



Classes 1 , 2, and 3 are arable. Class 6 is nonarable (lands which do not meet minimum requirements for arable land). The land class 

 assigned to a given soil unit is dependent upon the best judgement of the soil sdentisL 



References Cited: 



National Soils Handbook. SCS, USDA 

 National Soils Handbook Issue No. MT-2, SCS, USDA 

 Soil Survey Manual, Chapters 4 and 5, SCS, USDA 

 Land Classification Techiuques and Standards BOR, USDI 



8. Bulk dcmiry is used to express weight mcuurcmenu on a volume basis. As bulk densities apptx»ch 1 .5 to 1 .6 g/cm-', depending on totturc. 

 toot growth IS impeded and both aeration and water movement tmy be too low for optimum growth. 



9. Gtaviry-rype irngation should be mostly limited to slopes of 6 pertxnc or less in gcnetal gtadicni, and sprinkler-type irrigation limited to 

 slopes of 1 5 percent or less. 



10. The general depth to very slowly permeable or impermeable material that is a barrier to subsurface water movement shall be 7 feet or 

 greater. This includes dense clay and sandstone, siltstone. or shale bedrock. Permeability less than . 1 inch per hour. 



1 1 . Definition of Flooding Frequency: Rare - Floods less than once in ten yeat3; Occasional - Floods once in rwo to ten years; Frequent - 

 Floods at least once every two years. 



1 2. TTie growing season (frost-free season) must be long enough to produce crops on a long term basis, at least 7 out of 1 years. TTie base 

 reference crop is spring wheat. 



38 



