Agriculture Reference
In-Depth Information
In some highly weathered soils and semi-arid environments, essential soil nutrients, such
as P, are likely to be limiting and the options permitted under current organic standards may
be inadequate and considered unsustainable (Kirchmann and Ryan 2004, see also Chapter 2 ).
Furthermore, in some countries, the distance between farms and the primary sources of key
inputs is large and the range of inputs becomes severely restricted (Buresh et al . 1997).
Given that soil fertility is central to organic production, this aspect of negative nutrient
budgets should not be dismissed too easily because the question of P has been raised in a
variety of settings in Germany (Lampkin 1990) and the UK (Gosling and Shepherd 2005) and,
away from temperate Europe, in Sub-Saharan Africa (Pender and Mertz 2005) and Australia
(Penfold 2000). Based on current data, for some places in the world, rock phosphate will not be
able to provide plant-available P to the soil quickly enough (see Chapter 2 ). Biological, chemical
and physical methods of increasing the effectiveness of rock phosphate are being investigated,
with a focus on the following factors:
• mineral properties: reactivity, particle size, surface area;
• soil factors: pH, titratable acidity, P and calcium (Ca) availability and retention, sand
content, biological activity, organic matter content, moisture, temperature; and
• plant factors: P and Ca demand, root structure, rhizosphere pH (see Chapter 2 ).
However the effects are often neither significant nor important agronomically (Ryan and
Ash 1999, see also Chapter 2 ). Like collaborative research into sheep parasites, there are many
stakeholders interested in improving soil P availability.
Despite some serious but localised problems, organic farms are either already in practice or
are possible to establish in many agricultural settings (see Chapter 4 ). The constraints that
exist are often similar to those faced by conventional farmers (soil fertility, plant and animal
health) and there is considerable common ground in rectifying issues such as improved P solu-
bilisation and non-chemical parasite control in livestock. Some of the agricultural technolo-
gies that organic growers can and do use are now discussed.
Integrated farm management
Many different schemes have been established to devise and promote more efficient, less envi-
ronmentally damaging methods of agricultural production. A myriad of these integrated man-
agement schemes can normally be identified by their acronym, for example Integrated Pest
Management (IPM), Low External Input Sustainable Agriculture (LEISA) and Environmental
Management Systems (EMS). The common element among these concepts is that of achieving
production goals by integrating a diverse range of strategies in a planned but f flexible way. These
approaches have clear links with organic principles of diversity and rely on ecological processes
to aid production. In regard to managing crop protection, Letourneau and van Bruggen (see
Chapter 4 ) have distilled three important principles related to managing invasive species eco-
logically: prevention of colonisation or establishment, population regulation through biological
processes and curative interventions. Weed and animal health management would be expected
to operate on similar principles (see Chapters 1, 7 and Special topic 1 ).
As discussed, there is potential to learn from developing countries, such as those starting to
adopt organic farming methods. Indigenous agricultural knowledge systems offer many inno-
vative ideas for low-input farming that could be adapted for use on organic farms in other
countries (Nyeko et al . 2002, Vogt et al . 2002, Cools et al . 2003). The use of the plant neem
( Azadirachta indica ) is an especially well-recognised example of indigenous knowledge.
Organic plant and animal breeding uses classical methods of crossing and selection based
on desirable traits (see Chapters 4 , 5 and 6 ). The traits required for an organic ecosystem are
often different to traits for conventional farm ecosystems, thus requiring organic-specific
variety trials to determine performance. In plant breeding, various traits such as early vigour
Search WWH ::




Custom Search