Land evaluation – towards a revised framework
38
In this stage, confrontation with the local knowledge on the natural resources is
essential, so the need arises for participatory methods for land resource analysis and
for methods and guidelines for integration of participatory
methods and biophysical
survey. Land users might also possess valuable knowledge on land use requirements
and limitations. Over time they may have developed their own local land suitability
classes.
Research loop R1 was introduced by Young (1985 ). An important implication is
that it takes at least two to three years even
for annual cropping systems, and thus
prevents the immediate completion of the evaluation. A realistic way to overcome this
problem, according to Young (1985), is:
¾Complete the evaluation, using best available estimates
of performance where
knowledge is insufficient;
¾Note those land utilization types that have potential for improvement through
research and also those for which performance data are relatively uncertain;
¾Set up a programme of research into the improvement
of land utilization types
and assessment of their performance. Results from this research will be fed into
the land use planning process in due course.
The dual function of the research may be noted. First, it seeks to improve and
optimize land utilization types, e.g. through selection
of crop and tree varieties,
fertilizers or other aspects of management. Secondly, it determines the performance of
the improved systems, thus providing data for revision of the land evaluation.
Research loop R2 is related to biophysical research activities.
Information collected
in the land resource survey feeds other disciplines. An example of a specialized
study might be carbon sequestration assessment in soils. The assessment of carbon
sequestration involves two phases: measurement of soil carbon stocks and evaluation of
changes in carbon storage. Total organic carbon has to be determined at different depths
or for one or more horizons, and these data should be transformed
into mass of soil
organic carbon per unit land area, taking into account the bulk density and stoniness
of the soil. The data are then stratified by soil and terrain unit and extrapolated using
digitized soil and terrain maps and land-use information (FAO 2001). Changes in
carbon storage are estimated on the basis of historical examples and models.
Research activities related to local knowledge on the biophysical
environment such
as soil resources and water conservation also fit in research loop R2.
Chia sẻ với bạn bè của bạn: