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TOPIC 2: NEW ZEALAND
 

REVIEW REPORT FOR NEW ZEALAND

68. The Nex is calculated on feed consumption derived from the model by Clark et al. (2003) multiplied by a fixed factor of N in the feed of 3.7 per cent in DM for dairy cattle and 3.0 per cent for non-dairy cattle, sheep, and deer in combination with an animal nutrient turnover model which takes into account animals’ increased productivity and weight gain as well.  For other minor animal categories default IPCC values are used.

69. N-fixing crops such as clovers are used intensively in New Zealand pastures, and New Zealand is a major producer of clover seed. The use of N fixing crops increases the N turnover in soil from dead roots and root exudates and increases the N2O emissions compared with native soils.  The total N fixation reported in New Zealand’s inventory for 2004 is 3.7 Gg, or only 0.3 per cent of the total N fixation. New Zealand accounts only for N-fixation based on seed yield from pulses and peas.  The ERT recommends that New Zealand in its future inventories include the effect of changes in its management of grassland and other leguminous crops.

70. N2O emissions from crop residues returned to soils are estimated using the default IPCC method.  The overall emissions from this category have very little impact on the total emissions from agriculture (0.1 per cent).  However, the default methodology is very uncertain and improvements could be made where actual N content in crop residues (which are lower than the default values) are used as well as more precise national data on the amount of crop residues returned to soil.

4.  Pasture, range and paddock manure – N2O

71. The N2O emissions from animal excreta deposited on pastures is estimated using a country specific EF of 0.01 kg N2O-N/kg N based on measurements, while the IPCC default value is 0.02 kg N2O-N/kg N.  The NIR clarifies that an EF of 0.01 kg N2O-N/kg N is a proper value and that measurements continued until the measurements dropped down to background emission levels.  The chosen value is adequately addressed in the NIR and therefore the approach for emissions estimation is justified.