The image displays a classification of soil quality graded from good to
poor. Soil quality affects agricultural landuse capabilites in a
similar way to soil type. The soil quality layer was developed to make
use of the data on the characteristics of soils in the soil database without
adding each as a seperate input. The fundamental physical properties of
soil profiles relating to soil quality include; the rooting depth, soil
texture, water regime, slope, and existence of impermeable layers. Originally
these seperate inputs were weighted and summed using the grid module in
ArcInfo to give a soil quality proxy using basic grid commands.
Source data=Soils geographical
database of Europe at scale 1:1M version 3.2
Soils can be graded according to the degree of limitations which affect
its adaptivity. The grading would not necessarily enable soils to be grouped
according to the most profitable use to be made of the land, although they
could make interesting comparisons with actual landuse.
The present soil quality grading is based on physical limitations which
are fairly permanent and difficult to rectify, chemical and climatic interaction
effects are not taken into account.
Soil quality is relative to the type of crop you want to grow, the type
of soil, the climate and other factors, for example, grape vines grow well
on fairly thin poor sandy soils in hot sunny areas whereas wheat grows
better on nutrient rich darker alluvial soils in slightly wetter cooler
conditions. It should therefore be advantageous to specify soil quality
in relation to each landuse type.
More impressive classifications which take into account interactions with
climate and soiltype could develope this layer into a land capability measure.
Land capability classifications is less complex than soil suitability classifications
which require some form of landuse optimisation and would require consideration
of factors like distance to market, and farm structure.
A fuzzy soil capability classification based on these properties has been
designed to grade soils according to the severity of their limitations
for crop growth. This will hopefully be implemented in Classification 2.