III. RESULTADOS
3.1 Análisis de la Legislación Tributaria Peruana sobre
4*. Mandatory – Little effect on hill (except bracken spraying areas), but impact on uplands and associated lowland
*See Table 2 page 8
The use of most chemical pesticides, and all fungicides and herbicides whether as sprays or seed dressings are prohibited by organic farming standards. A limited range of insecticides such as insecticidal soaps are permitted for use in organic crop production. A very small number of naturally occurring products such as Derris and Neem are restricted by organic standards because they are harmful to beneficial pest- predators and permission for their use is only granted when absolutely necessary. Bio- rational practices such as the use of biological controls, encouraging pest predators and using varieties that are resistant to pests and diseases are the preferred methods in organic farming.
Where cereals crops have been grown in the past the organic Certification body may insist on a soil analysis to determine whether levels of chemicals such as Atrazine, which has a long residual life, still exist in the soil before land can be entered into organic conversion.
6.5.1 Biodiversity Impacts: Flora
The use of synthetic herbicides and pesticides has been shown to be one of the most significant impacts on wild flora (Unwin et al., 1995). The direct and indirect benefits of cessation of their use are:
o Re-introduction of broad-leaved weeds in cropped areas and recolonisation of associated invertebrates. Some weeds are desirable aesthetically and others are important sources of seed for some farmland bird species.
o Proliferation of flora and fauna species in non-farmed areas o No poisoning of non-target flora.
o Positive impacts on soil mycorrhiza and fungi
The avoidance of agro-chemicals is perhaps the lynchpin for the increase of floral diversity on organic farms. Productivity of crop plants grown may be affected by competing weed species and this is often a cause for concern for arable and horticultural farmers who contemplate the hand removal of weeds from their fields. The benefits to floral diversity are likely to be greater species diversity within crop, at crop margins and in the non-farmed areas.
The benefits to hedgerow and field margin habitats from cessation of spraying are that they are thereafter not subjected to spray drift and residues. This will enhance their existing role of becoming key areas of floral diversity on a farm and potential refuges for endangered species (Frieben and Kopke, 1996) and de facto encourage recolonisation out into fields.
6.5.2 Biodiversity Impacts: Fauna
As with flora species, the use of synthetic herbicides and pesticides has been shown to be one of the most significant impacts on wild fauna (Unwin et al., 1995). The direct and indirect effects of cessation of their use are:
o Proliferation of fauna species in non-farmed areas
o Increase in fauna in farmed areas, particularly invertebrates in arable areas and grassland.
o Increased insectivore breeding success due to increased food source o Better natural predator/prey balance reducing the need for pesticides o No poisoning of non-target fauna.
o No risk to beneficial insects. o Positive impacts on soil organisms
In lowland studies, the effect of nil-use of chemical pesticides and herbicides has been shown to be particularly beneficial to bird species which rely on farmland for food and nesting. The increased availability of seed and invertebrate food increases the chance of winter survival for adults and chicks and increased breeding success (Fuller, 1997). At Denmark Farm (an experimental, middle hill site with mixed grazing, in Mid Wales), the benefits of a total ban on pesticide use combined with other organic practices to promote biodiversity has shown a significant difference in breeding bird
numbers compared to a neighbouring farm using conventional hill farming practices (Bryngwyn Farm):
Site Acres Breeding Pairs Pairs
Species per Acre Bryngwyn 73 21 46 0.6 Denmark Farm 40 41 180 4.5 (Source BTO Common Birds Census 1994)
Wickramsasinghe et al (2003) found significantly higher bat activity on organic farms paired with on conventional farms. The activity of Myotis species was significantly higher over water habitats on organic farms than conventional farm water habitats. The authors relate this to agrochemicals applied to fields being a major source of aquatic pollution and suggest that localized changes in water quality account for the differences in bat activity.
6.5.3 Soil Quality Impacts
Because most pesticides are prohibited on organic farms, their impact on soil quality is negligible. Only copper, sulphur, natural pyrethroids and derris are permitted and only for use in protected cropping (Shepherd et al., 2003). The accumulation of copper fungicides is potentially problematic (Unwin et al., 1995) but is being addressed by changes in organic standards.
6.5.4 Air Quality Impacts
Cessation of threat from pesticide spray drift from aerial spraying of bracken.
6.5.5 Water Quality Impacts
The few materials that are permitted in crop production are only likely to enter water through misuse near watercourses or accidental spillage (Unwin et al., 1995). The limited capacity for crop production in the uplands further reduces the risk of contaminated run-off. Appendix 2 of IFOAM (International Federation of Organic Agriculture Movements) Basic Standards (IFOAM, 1998b) gives a complete list of permitted pest and weed control treatments. The use of all synthetic pesticides is prohibited.
6.5.6 Resource Use Impacts
The off-farm costs of conventional pesticide production are far greater than for production of the limited number permitted on organic farms. Pesticides are rarely used on organic hill and upland farms and therefore fuel costs for machinery are reduced but non-use may be compensated by mechanical weeding which negates on- farm benefits of fuel saving.