The Soils of Elgin County - Agriculture and Agri-Food Canada

Soil Suitability ClassesDescriptions of each of the classes in theclassification system are as follows :Class Sl - Soils in this class have no significantlimitations for crop growth and yields; soillimitations, if present, range from slight tomoderate.Class S2 - Soils in this class have moderate tosevere limitations for crop growth and yields .Class S3 - Soils in this class have severe limitationsfor crop growth and yields; management practicessuch as tile drainage or irrigation will result inincreased suitability for some crops .Class S4 - Soils in this class have very severelimitations for crop growth and yields;management practices such as tile drainage orirrigation will result in increased suitability forsome crops.Class N- Soils in this class have limitations whichare so severe that they are not suitable for specialcrops ; management practices such as tile drainageor irrigation do not increase suitability.Management Factors Which May AffectRatingstheThe soil suitability ratings given in Tables 6, 7,and 8 are based on inherent soil conditions andsurface features. Management factors such as theinstallation of the drainage or irrigation, however,will increase the suitability of many soils for arange of crops . The means to revise the ratingsfor these management factors, therefore, has beenincorporated into each of the rating tables .When the drainage or irrigation results in asignificant improvement in the soil suitabilityrating for a particular crop, the number of classesthe rating should be upgraded to is given in thetable . A numeric indicator of +1, +2, or +3, isshown in the table beside the appropriatemanagement factor. When the factors are notexpected to improve the rating, a dash is shown inthe table . For example, in Table 6 an Ayr soil ona simple B slope of 05 to 2% is rated Class S4 forasparagus . However, tile drainage would increasethe suitability of that soil for asparagus by twoclasses to Class S2 . This is indicated in the tableby a +2 beside "Drainage" . Irrigation is notexpected to increase the suitability of that soil forasparagus, and this is indicated by a dash beside"Irrigation'.Climatic ConsiderationsClimatic variables such as rainfall ortemperature were not considered to be limitingfactors in determining the soil suitability ratingsfor the identified crop groups . The micro-climateof a specific area, however, can have a directinfluence on crop growth and yields . Althoughthese conditions are important, they were notfactored into the ratings since they are difficult todefine at the scale of mapping .AssumptionsThe classification system, and the ratings givenin Tables 6, 7, and 8, are based upon the followingassumptions:(a) Good soil management practices that arefeasible and practical under a largelymechanized system ofagriculture areassumed.These practices include a proper fertilityprogram, management practices that result ingood soil structure and crop growth, andmanagement programs which result inminimum damage or risk of damage to thesoil;Distance to markets, accessibility to transport,location, size of farm, field shape andaccessibilty to machinery, type of ownership,cultural patterns, skill or resources ofindividual operators, or hazards of cropdamage by storms are not considered in thisclassification system;(c) Soil suitability ratings are subject to change ifnew technology or management practices suchas tile drainage or irrigation are widelyadopted, or as new information about cropyields or the behaviour and responses of thesoils becomes available.(2) How to Determine Special CropSuitability Ratings for Areas on theSoil MapsThe soils or land units which occur withinareas shown on the soil maps are identified in themap symbols for those areas . Explanations for themap symbols and their components are providedon each map in the section titled "Key to the MapSymbols" . Similar explanations are also given inthe Glossary at the back of this volume of thereport. Symbols shown on the maps mayrepresent one of the following- 1) a land unit; 2) asingle soil type which occurs on a single slope, 3)a single soil type which occurs on two differentslopes; and 4) two different soil types.When two slopes or two soil types areidentified in the map symbol, dominant andsignificant soils occur for which suitability ratingsmust be determined . Dominant means that 40 to62