2010-04-14_GENERAL DOCUMENTS - C1981008

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622 =2 Part. 622 :- Interp $eta -Delta complex, 0 to 3 percent slopes Beta silt lown, 1 to 3 percent slopes Delm silt loam, 0 to 1 percent slopes ............ ....... . rezative Grtaups' He (c) References, Agricultural Handbook 210 discusses the definition, purpose, lirnitations, and assumption Ile of'the Land Capability Classification Systetn, The Guide to Authors for Soil Survey I Manuscripts is also helpful, Alpha -Beta complex, A's 2 to 6 percent slopes Alpha silt loam., Qe 2 to 5 percent slopes Beta gravelly silt learn, id's 2 to 6 percent slopes Alpha -Dock outcrop co nplex VIs 4 to 8 percent slopes Alpha silt loath IIIc Roclt outcrop VIdI (3) Soil map units named as an undifferentiated group of soil series. These map units are assigned a single capability classification. By definition, an undifferentiated group is recognized because the use and n rta.gement of the component soils are similar, Examples follow: Alpha and Beta soils, We severely eroded Rock outcrop and VIE Rubble land (4) Soil trap units that are rn scellarnevus areas. These map units are typically uniform enough in regard to their restrictions in use that a single capability classification may be assigned. A capability classification is as,sigited to all miscellaneous areas except water. Examples follow: Urban land VIII Rubble land Vlll (S) Soil trap units named for taxonornic. classes above the family level. These snap units are, where possible, assigned to a capability classification in the sarne manner as sail series and faunilies. 622.03 Prime Farmland Sails. (a) Definition, Prime farmland is land that has the best combination of physical auad chemical characteristics for producing food, feed., forage, filer, and oilseed crops atad that is available for these uses. It has the cumbination of soil properties, gnawing season, and moister; supply needed to produce sustained high yields of crops in an econotnic mamner if it is treated and Managed according to acceptable f"rig methods. In general, prime farrniand has an adegWe and dependable water supply from precipitation or irrigation, a favorable temperature and grousing season, an acceptable level of acidity or alkalinity, an acceptable content of salt or sodium, and few or no rocks. Its soils are permeable to water and air. Prime farmland is not exce*sively eroded or saturated with outer for long periods of time, and it either does not flood frequently during the growing season or is protected from flooding. Users of the lists of prime fartmiland map units should recognize that sail properties are only one of several criteria that are necessary. Other considerations include: (1) Land use - Prime farmland is designated independently of current land rase, but it cannot be areas water or urban or built -up land as defined for the National Resource Inventories. Map units that are complexes or associations containing components of urban land or miscellaneous areas as part of the map unit name, cannot be designated as prime €arrnland. The soil survey memorandum of understanding determines the scale of mapping and should ref[ ct local land use interests in designing of map units. ? Frequency of flooding - Some nap units may include both prime farmland and land not prime farmland because of variations in flooding frequency. (3) Irrigation - Some map units innclude areas that have a developed irrigation water supply that is dependable and of adNua.te quality and areas that do not have such a supply. In (430- VI -NSSH, Nov. 1993)