Agriculture Reference
In-Depth Information
is problematic. Unlike water and air where 'fitness of use' can be related
directly to a single function (i.e. human consumption), soil has multiple
functions and is only related indirectly to human welfare (Oliver, 1997).
Furthermore, a significant part of soil quality (i.e. inherent quality) that
involves some important soil properties and attributes (e.g. particle size dis-
tribution and mineralogy) are not readily subject to human manipulation
and are relatively static. This aspect of soil quality has long been addressed
by land resource and soil survey inventories. Other properties and attributes
of soil quality (i.e. dynamic quality) that include, for example, organic
matter and structural properties (e.g. porosity, permeability and aggrega-
tion), can be subject to relatively rapid change and responsive to soil
management.
An ecological framework used to evaluate soil quality is given in Table
1.1. The framework is based on the following logical sequence: purpose,
function, processes, properties (including critical values), indicators and
methods (including standardization).
Soil Organic Matter Quality Evaluation
The soil quality framework given in Table 1.1 can also be applied to
evaluate those soil functions specifically related to soil organic matter.
Generally, the limiting steps in the above sequential framework for soil
organic matter evaluation are the setting of 'critical values', the choosing of
suitable attributes or 'indicators', and 'standardization'.
Table 1.1. Sequential framework to evaluate soil quality for specific purpose or fitness of use
(after Carter et al., 1997).
Sequence steps
Sequential framework
Questions implied by the framework
1.
Purpose
What will the soil be used for?
2.
Functions
What specific role is being asked of the soil?
3.
Processes
What key soil processes support each function?
4.
Properties/attributes
What are the critical soil properties for each process?
What are their critical or 'threshold' values?
5.
Indicators/surrogates/
pedotransfer function
When the attribute is difficult to measure or not
available, which indirect or related property or
properties can be used in its place?
6.
Methodology
What methods are available to measure the attribute?
Standardization
Technical rules and protocols for soil sampling,
handling, storage, analysis and interpretation of data.
 
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