Tamar report land Capability Survey of Tasmania k e noble 1992 Tamar Report

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8.1

Class Definitions

CLASS 1

Multiple use land with virtually no limitations to intensive cropping and grazing.  It occurs

on flat land with deep, well drained soils, and in a climate that favours a wide variety of

crops.  It is capable of being cropped eight to nine years out of ten in a rotation with pasture

or equivalent.

CLASS 2

Land suitable for intensive cropping and grazing. Limitations to use are slight, and these

can be readily overcome by management and minor conservation practices.  Limitations

reduce the length of the cropping phase to five to eight years out of ten in a rotation with

pasture or equivalent.

CLASS 3

Land suitable for cropping and intensive grazing. Cultivation for cropping should be

limited to two to five successive crops in a rotation with pasture or equivalent.  Soil

conservation practices and sound management are needed to overcome the moderate

limitations to cropping use.  The range of crops able to be grown is generally more

restricted than on Class 1 or 2 land.

CLASS 4

Land marginally suitable for cropping because of limitations which restrict the range of

crops that can be grown, and/or make major conservation treatment and careful

management necessary.  Cropping rotations should be restricted to one to two years out of

ten in a rotation with pasture or equivalent.  This land is well suited to intensive grazing.

CLASS 5

Land with slight to moderate limitations to pastoral use.  This land is unsuitable for

cropping, although some areas on easier slopes may be cultivated for pasture establishment

or renewal.  The effects of limitations on the grazing potential may be reduced by applying

appropriate soil conservation measures and land management practices.

CLASS 6

Land marginally suitable for grazing because of severe limitations.  This land has low

levels of production, high risk of erosion, low natural fertility or other limitations that

severely restrict agricultural use.

CLASS 7

Land with very severe to extreme limitations which make it unsuitable for agricultural use.

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8.2

Guides for Identifying the Land Capability Classes

Class 1 land has most or all of the following features :

•

 

land is level or very gently sloping with slopes less than 5%,

•

 

soils are deep, freely drained and have high water holding capacity,

•

 

surface drainage is adequate,

•

 

productivity is high for a wide range of crops,

•

 

erosion hazard is nil to slight,

•

 

soils have a high capacity to withstand frequent cultivation and irrigation without

serious damage under sound, average management,

•

 

soil physical and chemical deficiencies can be readily corrected,

•

 

climate does not seriously affect productivity,

•

 

soils do not have excessively high sand or clay contents.

Class 2 land has most or all of the following features:

•

 

slopes may range up to 12%,

•

 

soils are deep and freely drained, and have moderate to high water holding capacities,

•

 

soils have a moderate to high capacity to withstand frequent cultivation and irrigation

without serious damage under sound, average management,

•

 

minor conservation measures may be required,

•

 

productivity is high to moderately high for a range of crops,

•

 

adverse soil characteristics can be easily improved,

•

 

the risk of flooding is low.

Class 3 land has most or all of the following features:

•

 

slopes may range up to 18%,

•

 

high to moderately high levels of productivity under improved pasture species and

crops,

•

 

the range of crops is generally more restricted than on Class 1 or 2 land,

•

 

soil depth and drainage can be variable,

•

 

conservation measures are necessary under cropping,

•

 

soil physical features and/or slope restrict the amount of cultivation the land will

tolerate between pasture phases.

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In addition they may have a range of limitations from among the following:

•

 

slope,

•

 

erosion hazard,

•

 

adverse soil characteristics (e.g. stoniness, internal drainage, soil structure, nutrient

deficiencies),

•

 

salinity hazard,

•

 

periodic flooding,

•

 

climate.

Class 4 land has a similar set of limitations to those described above for Class 3 but the

limitations are more severe so that only occasional cropping is possible, and/or the range of

crops able to be grown is severely restricted.  Slopes may range up to 30%.  Major soil

conservation practices may be necessary under cropping.

Class 5 land has many of the following features:

•

 

slopes can range up to around 40%,

•

 

land may be broken by gullies and surface irregularities,

•

 

the degree of stoniness, wetness or other physical limitations prevents the cultivation

of the soil for cropping,

•

 

erosion hazard may be moderate to severe,

•

 

nutrient deficiency, acidity or salinity may depress but not prevent plant growth.

Class 6 land is often very steep, rocky or wetlands.

The land may have either a single very severe limitation or a combination of several severe

limitations from among the following:

•

 

slope,

•

 

stoniness or rockiness,

•

 

erosion hazard,

•

 

soil physical limitations,

•

 

salinity,

•

 

surface water, flooding,

•

 

nutrient deficiency,

•

 

climate, altitude.

These limitations make this class of land unsuitable to be cleared for grazing and steeper

areas should be left under a vegetative cover, because of the potential erosion hazard and

low productivity.  Conservation measures including revegetation or retention of existing

vegetation cover should be adopted.

Class 7 land has a similar set of limitations to those described for Class 6 but the limitations

are very severe to extreme, making this land unsuitable for agricultural use.

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