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.

During the 20th century, US agriculture underwent vast transformations. The number of farmers has decreased, more farmers are relying on off-farm income, agriculture's proportion of the US GDP has declined, and a minority of non-metro counties in the US are farming dependent. Agriculture's evolution will continue and we have identified key trends and future challenges to effectively manage our changing agricultural system. Eight current trends in US agriculture were identified. These included: (1) increased land degradation; (2) competing land uses; (3) focus on single ecosystem service; (4) increase in farm size; (5) movement toward commercialization; (6) genetic engineering; (7) global markets; and (8) changing social structure. Future trends likely to affect agriculture include: (1) diminishing and increasingly volatile farm incomes; (2) reduced government involvement in food regulation; (3) continued transition from farming to agribusiness; (4) land-use will become a major issue; (5) increasing animal protein consumption in the US; (6) increased public input on livestock production practices; (7) increasing urbanization of historically rural US counties; (8) increased public concern over food safety; (9) increased medicinal production from agriculture; (10) new tastes, markets and opportunities will emerge. We further postulated that future challenges facing US agriculture might include: (1) competitive pressures; (2) sustainable development; (3) resource conservation; and (4) research and development. Integrated agricultural systems may be flexible enough to address these challenges. However, robust principles will be needed to design adaptable integrated agricultural systems. We present a nonexclusive list of preliminary principles under the four general categories of (1) economics and economic policies; (2) environmental; (3) social and political; and (4) technological.