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Issue 13 September 2003
From the EditorAs Editor, I am pleased to be able to produce the following RM Update on MAF operational research projects as my last issue of RM Update. In the future, RM Update will be edited by Sharon Thurlow and Saphron Powell from the MAF Sustainable Resource Use team. Each year MAF commissions research which provides information to assist in policy development and implementation. This research is often of interest to those associated with the primary production sector. Results of this past research and details of current research can be accessed on the MAF website at: www.maf.govt.nz/mafnet/rural-nz/research-and-development . The following RM Update articles focus on recent operational research associated with sustainability issues. Duane Redward, Editor |
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Intensive Cattle Grazing
This article by Duane Redward discusses an operational research project carried out by Alec Mackay, AgResearch and Tony Rhodes, Agriculture NewZeland on changes in cattle policies in the North Island and the environmental impact of intensive cattle policies.
Little information exists on the changes in cattle policies on rolling and hill land over recent years and the impact of these on the environment. This lack of information, combined with concerns over the environmental effect of intensive cattle grazing, prompted MAF Policy to commission research in 2001 into intensive cattle grazing systems.
Thirty producers were contacted, representing intensive dairy bull beef finishing, through to traditional beef breeding cow operations. The producers were farming a range of terrains from sedimentary or volcanic soils on rolling and hill land in the summer dry Central Hawkes Bay, to summer moist Rangitikei regions of the North Island. In one-on-one interviews, information was collected on the changes in farmers’ cattle policies over the last 5- 10 years and likely future changes. Their assessment of the impact of the current cattle policy on soil erosion and soil and pasture damage was also recorded, as was the current management actions taken to limit any negative impacts. Comment was also sought on the long-term impacts of future intensification on the environment.
The survey found that cattle policies have intensified over the last 5 to 10 years in Hawkes Bay, as indicated by increased cattle-to-sheep ratios, stocking rates, growth rate targets and grazing management systems such as cell grazing. Rangitikei farmers appeared to have moved from breeding cows systems to younger cattle grown more intensively. Cows were managed more intensively in Hawkes Bay than Rangitikei.
Twenty-four of the 30 participants in the survey intend to continue with intensification of their cattle policies. All farmers had or were in the active process of implementing on-farm “land management practices.”
With the exception of two, all participants in the survey assessed the short-term impact of their current cattle policy on the soils and pastures on the farm as minimal. The link between cattle treading and subsequent soil and pasture damage was viewed as weak and short-term in nature by the Central Hawkes Bay farmers. Individual participants in the Hawkes Bay group did, however, express concern regarding the long-term impacts of cattle treading on soil compaction, nutrient run-off to surface watercourses, on green house gas emissions and on pest plants.
Compared with the Central Hawkes Bay group, direct negative treading effects on soil and pastures was regarded by the land owners in the Rangitikei District as more serious, leading potentially to substantial loss of pasture production. Pads, sacrifice areas and cultivation to restore damaged areas were seen as an integral part of the strategy on many of the Rangitikei farms. Typically, these options tend to be focused on the consequences of the cattle policies, rather than the fundamental design and “fit” with the constraints of the resource. None of the participants had attempted to quantify the loss in pasture production following treading damage.
Half the participants in each group believed that more could be done to reduce the impacts of current practice and more would need to be done with continued intensification. Most participants identified increased knowledge as a critical success factor for the future. Time and money were identified as the barriers to gaining the additional knowledge. All participants indicated that the barrier to adoption could be reduced in situations where the dollar benefits of increased knowledge could be demonstrated.
Quantitative information on the impact of intensive cattle treading on the soil and pasture resource was assessed on nine of the survey farms in the two regions in the late winter and spring of 2001. Of the measurements made, producers were familiar with pasture cover and soil fertility status, but not those used for assessing soil or pasture damage. All nine-survey farms showed evidence of soil and pasture damage following cattle grazing. This was reflected in measurements of the amount of bare ground, macro-porosity and the soil indicators of the Visual Soil Assessment. At five of the nine sites the macro-porosity values were low (8.4-11%) on the undamaged area, suggesting the soils, which included both volcanic and sedimentary soils, were already under pressure from previous livestock policy and management. The loss of “soil physical condition” has the potential to reduce pasture growth, increase runoff and sediment losses, reduce infiltration rates and nutrient use efficiencies, and increase greenhouse gas emissions (i.e. nitrous oxide).
A number of recommendations are made in the report. The report indentifies several gaps in our current knowledge and points to where further support could be given to assist with managing treading effects as cattle systems continue to intensify. A structured survey is required on a national level or on at risk regions to collect data on the actual changes in cattle numbers and stocking rates. The long-term implications of ongoing intensification on the soils resource and wider environment require a more detailed analysis. The development of resource material to assist landowners in quantifying the effect of treading damage using the “new tools”, and in evaluating systems design and refining management practices is needed. Documentation on the relative merits of the management options currently available for managing treading effects on the farms is required, with a focus on fundamental design and “fit” with the on-farm land resources. A series of case studies, examining the costs and benefits of managing treading effects, would provide a guide to future land use practices and new information on what are sustainable cattle stocking policies and management for rolling and hill land.
Duane Redward
Regional Policy Analyst
MAF Policy Information and Regions
Duane has been employed by MAF for four years in the Hastings office. He is involved in Sustainable Land Management issues with a particular focus on erosion and biodiversity. In addition, Duane is involved in farm and pipfruit monitoring, pipfruit industry issues, primary sector taxation and is responsible for the production of RM Update.
Contact for Enquiries
Amber Duncalfe
Editor - RM Update
Ministry of Agriculture and Forestry
PO Box 2526
Wellington
NEW ZEALAND
Tel: +64 4 894 0710
Fax: +64 4 894 0745
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