La participación ciudadana en la política municipal

The previous sections provided a summary of the theory of trade and outlined some common tariff and non-tariff trade restrictions and their impacts on a country using a partial equilibrium approach. In this section, the relationship between trade and the environment will be briefly described because in some cases the assumptions of markets do not hold and markets fail. The section finishes with an outline of the theory of GHG emissions.

One condition underlying the workings of a market is that they assume perfect competition. In order to have perfect competition, several requirements need to be met. This is that numerous firms offer an identical good on the market with many buyers available for these products; there is perfect information on the market and no external costs occur. Finally, property rights are clearly defined in a perfectly competitive market. If any of these conditions is not met, then the analysis of a market with perfect competition may not apply and the market may fail due to imperfectly defined property rights, imperfect information, external costs and only small numbers of buyers and seller, with restrictions to enter and exit the market (Randall, 1987). Market failure may occur through environmental pollution or GHG emissions. In the context of climate change, GHG emissions are negative externalities9 _{generated by production and}

consumption of certain products which represent a cost that is not transmitted through market prices. For example, producers of livestock do not pay for the costs of GHG that are emitted during the production of their product (Wreford, 2006).

3.6.1 Theory of agricultural GHG emissions

Agricultural GHG emissions are predominantly generated by two sources, animal numbers and the use of nitrogen; and methane (CH4) and nitrous oxide (N2O) are the two main GHG

generated by agricultural production. Methane emissions from livestock are predominantly generated through digestion (“enteric fermentation”) and ruminant fecal waste decomposition (“manure management”) (IPCC, 2007). The amount of CH4 emissions is determined by type

and quality of animal feed and the amount of feed intake (Lassey, Lowe, Manning & Waghorn, 1992).

While N2O is emitted in lower quantities than CH4, it has a significant effect on agricultural

GHG emissions due to its high global warming potential (GWP)10_{. Nitrous oxide is generated}

from several sources within the agricultural production process. Firstly, N2O is emitted through

animal waste management systems (Cagatay et al., 2003). The IPCC (1996) identified six alternative systems for animal manure treatment: this is anaerobic lagoon, liquid systems, daily spread, solid storage and drylot, pasture range and paddock, used fuel, other system. Secondly, N2O is directly emitted from agricultural soils resultant from synthetic fertiliser application, the

use of animal waste as fertiliser, nitrogen-fixing crops, and crop residues. Thirdly, N2O is

emitted from animal production through direct soil emissions which refers to manure on grassland from grazing livestock and left there for decomposition. Fourthly, N2O indirectly

emitted by nitrogen used in agriculture which are generated from atmospheric decomposition of ammonia and nitrogen oxides, and leaching (IPCC, 1996).

In order to determine CH4 and N2O emissions for a country or for the supply of the meat and

dairy sector, livestock numbers are used, among others (Cagatay et al., 2003). A guideline for the calculation of coefficients for CH4 and N2O emissions from livestock was developed by the

IPCC methodology for greenhouse gas inventories (1996). Default emission factors were produced by the IPCC for the calculation of coefficients for different sources of gases, for different countries. Recently FAOSTAT (2013) also determined emissions factors for several countries. Mostly, the CH4 and N2O emissions from these sources are converted to their CO2

equivalents by multiplying with their respective weights (21 and 310) to give CO2 equivalents

(IPCC, 1996). Hence, GHG emissions from livestock differ between countries and these values will vary considerably within each region. Therefore, New Zealand, as have many other countries, has conducted further research to produce more accurate emission factors (Wreford, 2006; Cagatay et al., 2003).

Groundwater nitrate contamination

Another main issue with the potential to cause environmental degradation from agricultural production is groundwater nitrate contamination due to the use of nitrogen fertiliser. Although this issue is not directly part of this study, it has a significant impact and is therefore briefly described.

In particular, dairy production has been identified to cause high nitrate concentrations in groundwater, both directly, through the application of nitrogen fertiliser on grassland and

10 _{GWP is a CO2-weighting. It is a relative measure of how much heat a greenhouse gas traps in the atmosphere}

indirectly, through the nitrogen content of grass and other feeds deposited in urine and manure (Rae, 1999). Bidwell (1999) developed an environmental damage function of how the environmental impact of dairy production can be measured as shown in Equation 3.1. He demonstrated that nitrogen fertiliser (Na/ha) and the amount of concentrated feed grain (ka) used in each region (shown for region a in Equation 3.1) both contribute to nitrate emissions with some of their nitrogen content removed in milk (qsa). Whitehead (1995) defined the impact of emissions on groundwater concentrations (GNCa) dependant on the degree of dilution through annual drainage (see Equation 3.1).

𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺 = (𝑥𝑥0+𝑥𝑥1 𝑁𝑁𝑁𝑁+𝑥𝑥2 𝑘𝑘𝑁𝑁−𝑥𝑥3 𝑞𝑞𝑞𝑞𝑁𝑁)_𝑊𝑊 (3.1)

GNCa: average groundwater nitrate concentration in region a (g/m3_/yr)

Na: nitrogen use in region a (kg/ha/yr)

ka: feed grain (concentrate) use in region a (kg/ha/yr)

qsa: quantity of raw milk produced in region a (l/ha/yr)

W: annual average drainage per year (mm)