A study of the physical condition of soils under dairying in the Waikato and Northland regions was undertaken to determine the physical condition of the soil, possible changes from pugging damage, and the most appropriate measurements and sampling regimes for monitoring change.Sites were selected on widespread soil types (Allophanic and Gley Soils in the Waikato; Allophanic, Ultic, and Podzol Soils in Northland) and corresponded to never trodden, usual usage or conditions, and previously pugged (>18 months ago) pasture. Soil cores were collected at 50-mm depth increments for determination of bulk density, total porosity, saturated and unsaturated hydraulic conductivity, proportion of pores greater than 30 and 60 µm, and aggregate size class.The 0-100-mm depth was best for showing differences between treading regimes. Within this depth, hydraulic conductivity and aggregate size showed the greatest differences between regimes. All measurements were useful for showing differences in the Waikato data. However, for Northland, bulk density, total porosity, and proportion of pores were not always indicators of change. Approximately 20 cores were needed per regime to show differences. Soil properties on most soil types were still affected 18 months after a pugging event. Measurements selected for showing change varied depending on whether data were for geographic regions, a single region, or a particular soil type.
Assessment of energy use and greenhouse gas emissions associated with dairy products needs to account for the whole life cycle of the products, particularly with the debate about "food miles"(the transportation of product from producer to consumer). A life cycle assessment (LCA) of an average NZ dairy farm for 2005 showed that total energy use per kg milk from the "cradle-tomilk- in-the-vat" was 45-65% of that from EU farms. The greenhouse gas (GHG) emissions or carbon footprint showed similar relative trends although differences were smaller due, at least in part, to lower methane efficiency from lower-producing NZ cows. Energy use associated with shipping dairy product (e.g. cheese) from NZ to UK is equivalent to about one-quarter of the on-farm use. Even when added together, the energy use from the NZ farm and from shipping would still be less than onfarm energy use for the EU farms. However, this is affected by intensification and the Dexcel Resource Efficient Dairying trial showed that increasing maize silage use, and nitrogen fertiliser use in particular, increased the energy use and GHG emissions per kg milk by up to 190% and 23%, respectively. Thus, the trend for intensification on NZ dairy farms means that our comparative advantage with EU farms is diminishing. A focus on improved farm system practices and integration of mitigation options is required to reverse this trend. Keywords: food miles, greenhouse gases, energy, life cycle assessment, milk, New Zealand, efficiency
The user inputs to OVERSEER® Nutrient Budgets (Overseer) allow farm-specific greenhouse gas (GHG) emissions to be estimated. Since the development of the original model, life cycle assessment standards (e.g. PAS 2050) have been proposed and adopted for determining GHG or carbon footprints, which are usually reported as emissions per unit of product, for example, per kg milk, meat or wool. New Zealand pastoral farms frequently generate a range of products with different management practices. A robust system is required to allocate the individual sources of GHGs (e.g. methane, nitrous oxide, direct carbon dioxide and embodied carbon dioxide emissions for inputs used on the farm) to each product from a farm. This paper describes a method for allocating emissions to co-products from New Zealand farms. The method requires allocating the emissions, first, to an animal enterprise, separating the emissions between breeding and trading animals, and then allocating to a specific product to give product (e.g. milk, meat, wool, velvet) footprints from the 'cradle-to-farm-gate'. The meat product was based on live-weight gain. Procedures were adopted so that emissions associated with rearing of young stock used in live-weight gain systems, both as a by-product or a primary product could be estimated. This allows the possibility of total emissions for a meat product to be built up from contributing farms along the production chain.
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