APPENDIX D 

 RWRCC LAND CLASSIHCAnON SPECinCATIONS 



When switching to next 

 Land Ouraaeristics 



lower class, soil must satisfy all 

 Class 1 



criteria for that class. 

 Class 2 



Class 3 



Soils 



Surface texture for 

 8 inches' 



Texture profile 

 Coarse 



Fine 



Depth to coarse sand, 

 gravel or cobble material^ 



Depth to dense clay, 

 sandstone, siltstone, 

 or shale bedrock' 



Available water- 

 holding capacity'* 



Permeabillcv' 



Salinity in root zone* 



Sodidcv in root zonc^ 



Sandy loam through 

 friable dav loam, SL, 

 FSL, VFS'U L. SIL SI. 

 SCL. CL, and SICL 



Sand permitted below 

 40 inches. 



No day, silty day or 

 sandy day in upper 36 

 inches. 



Minimum 48 inches 



Minimum 84 inches. 



Six inches or more in 

 upper 48 inches. 



.2 inch to 6 inches per _ 

 hour. 



Salt content can be 

 maintained at a level not 

 to exceed 4 millimhos per 

 centimeter. 



Sodium -Adsorption Ratio 

 (SAR) less than 13. and 

 no physical deterioration 

 of soil. 



Coarse sandy loam to 

 [jermeable day. COSL, 

 SL FSU VFSL L SIL. 

 SI. SCL CL SICL SC, and 

 C. May be gravdly. 



Loamy coarse sand or sand 

 permirted bdow 30 inches. 



Permeable day permitted 

 below 12 inches. 



Minimum 36 inches. 



Minimum 84 inches. 



Greater than 4.5 inches 

 in upper 48 inches. 



Greater . 1 inch to 20 

 inches per hour. 



Salt content can be 

 maintained at a level not 

 to exceed 6 millimhos per 

 centimeter. 



Sodium Adsorption Ratio 

 (SAR) less than 1 3. some 

 physical deteriorarion of 

 soil, and permeability 

 somewhat impaired. 



Loamy sand through permeable 

 day LS, LVFS, COSL SL, VFSL 

 SIL SI, SCL CL SICL SC, SIC, 

 and C. May be gravelly, cobbly. 

 Class I stoniness. 



Loamy, coarse sand 

 permitted bdow 18 inches. 



Entire profile may be permeable 

 day if infiltration rate is adequate 

 for plant moisture requirements. 



Minimum 18 inches. 



Minimum 84 inches. 



Greater than 3 inches in 

 upper 48 inches. 



Greater than . 1 inch per 

 hour. 



Salt content can be 

 maintained at a levd not 

 to exceed 8 millimhos per 

 centimeter. 



Sodium Adsorption Rario (SAR) 

 less than 20, physical deteriorarion 

 of soil, and fjermeability impaired. 

 Permeability must be 0.2 inch 

 per hour in the top 24 inches. 



1. Ail surface tcxuira and soil depchs arc dependent upon water holding capacities. Gravelly - less than 35% gravel (less 3 inches) in diameter, 

 cobbly - less 33% cobbles (3 co 10 inches) in diameter, stones (10 to 24 inches) in dbmctcr. Class I stoniness - stona cover less than 0.01 

 percent of surface. 



2. All surface textures and soil depths are dependent upon water holding capacities. 



3. The underlying geologic materials linit or prevent root penetration and pcrmeabilirv is Impaired. 



4. Soils with available water holding capacities of less than 3 inches in the upper 48 inches arc Class 6 land. 



5. Soils with a permeability of less than .1 inch per hour in any significant layer of the root zone arc Class 6 land. 



6. Soils dominated by montmorillonite clav arc more difficult to manage than those dominated by illite or kaolinite and respond to lower levels of 

 salinity. If the soil exceeds 8 millimhos per centimeter it must have good permeability (.2 inch per hour or greater) throughout the rcxjt zone. 



7. The physical deterioration of the soil is caused bv the dispersion and swelling of clays. These interrelated phenomeru both aa to reduce 

 permeability (hydraulic conductivity) of the soil. Type of mineralogy, and salinity must be taken into account. Sodium Adsorption Ratio (SAR) 

 should be less than 10 in some fine (day) textured soils but may range to 20 in coarse (sandy) textured soils with adequate drainage. 



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