Field days focus on sustainability and production efficiency

In a recent project supported by the Ministry for Primary Industries, the AgResearch Farm Systems team introduced deer farmers to the implications of their current farm systems on climate change and greenhouse gas emissions through a number of presentations and discussions at ‘Deer Focus Farm’ field days.

Deer farming is a significant pastoral land use in New Zealand with an estimated 1.2 million deer (700,000 hinds and 500,000 stags) farmed on some 3,000 farms covering 341,000 hectares. This is estimated to represent about half the total global farmed deer population. Deer are often farmed as a secondary enterprise alongside other livestock, but there are an estimated 2,300 farms on which deer contribute more than 50% of the farm revenue.

Science Leader Dr Robyn Dynes says the group recognised that the project focused on building awareness at regular events which considered the impact of applying different farming systems and their impact on farm production, productivity, profitability and greenhouse gas emissions.

“AgResearch scientists Dr David Stevens and Dr Andrew Wall worked with the numerous existing deer industry field days and introduced some new information about the effects of different farm system models,” says Dr Dynes.

Three field days were held on Waikato-Bay of Plenty, Canterbury and Southland focus farms which covered a broad range of regions, climates, soils and livestock mixes. Baseline modelling was completed for all three farms and the emissions from each were calculated using the Overseer® nutrient budget model. Potential changes in farm management systems were modelled in Farmax with a view to increase production levels and profitability.

Dr Stevens led a different discussion focus on each of the farms, but all three considered production systems, profitability and greenhouse gas mitigation.

Each of the field days was well attended with between 40 and 140 farmers at each so the presentations reached at least 10% of New Zealand’s deer farmers, accounting for approximately 25% of the deer herd, to increase their awareness of the challenges and opportunities that the issues of climate change present.

“The focus was very much on things that they could do on their farms and covered topics that were relevant to them and their region and to growing their industry,” says Dr Dynes.

“The field days also provided some understanding that there were various options available to build resilience in their farming systems and opportunities to offset greenhouse gas emissions in addition to forestry.”

She says a common theme at all of the field days was that one of the best mitigation strategies for offsetting any costs incurred from greenhouse gas emissions was increasing the production efficiency of the farm.

“While a lot has been said about the use of tree planting to offset the greenhouse gas emissions from pastoral farms including deer farms, our whole farm models suggest that integrated solutions which include improving production efficiency may be the best approach,” says Dr Dynes.

“In each scenario we modelled using Farmax and Overseer®, deer farmers were better off concentrating on improving production efficiency rather than reducing inputs or retiring land – this has benefits for business resilience and for industry growth.

“Emissions are expressed in two ways – first in tonnes of greenhouse gas produced per hectare and the second in the amount of greenhouse gas produced per kilogram of product produced on the farm.

“The research demonstrated the interaction between profitability and environmental impacts. In several cases the output of greenhouse gas emissions per unit of product sold was reduced while the total greenhouse emission per hectare increased.

“However by increasing the efficiency of production the intensity of greenhouse gas emission is reduced.”

Dr Dynes says the models showed the best mitigation strategies for deer farmers were those that increased the production efficiency by increasing the growth rates of finishing stock, minimising the number of unproductive animals and by minimising animal deaths. These were more profitable, added to resilience and therefore industry sustainability.

“Many of the strategies tested for reducing the intensity of greenhouse gas emissions were closely aligned with the current objectives of the deer industry: more calves, heavier and earlier.”