Winter can be a critical time for soil erosion, stream pollution and animal welfare on livestock farms. Some wintering systems, especially brassica and fodder beet crops, pose particular risks to water quality with exposed soils becoming saturated, pugged and carried away during heavy or prolonged rain into waterways. As well as carrying soil particles, this runoff contains high levels of phosphorus, nitrogen and bacteria that are a risk to downstream water quality.
Intensive winter grazing (IWG) has become publicly controversial in recent years. Much of the focus has been on poor practice on dairy farms, but some unfortunate incidents on deer farms have also been brought to public attention on social media and in television newscasts.
In 2020, the government proposed to introduce a National Environmental Standard (NES) to control intensive winter grazing (IWG) practices in 2021. In March 2021, the standard was deferred until May 2022 to give farmers time to modify their wintering practices and to demonstrate that the proposed NES need not be as prescriptive as first proposed.
It is therefore crucial for deer farmers to adopt best winter grazing practices at all times, but particularly in the winter and early spring of 2021. Regional Councils will be stepping up their monitoring and activists will be looking for examples of bad wintering practice as part of their campaigns for stricter regulation.
To encourage farmers to adopt best practice for the current season (2021) farming groups – including Deer Industry New Zealand – have developed a checklist of good practices.
From 2022 onwards farms will require an IWG module (management plan): the Ministry of Primary Industries and the Ministry for the Environment have developed a module that explains what farmers need to do to meet the expectations of government, the wider public and their fellow farmers.
Good wintering systems and practices minimise soil disturbance and erosion. Whatever wintering system is used, environmental effects need to be closely monitored and appropriate mitigation measures undertaken. The environmental impact of a wintering system will depend on-
- its day-to-day management;
- the extent of its soil disturbance;
- the weather;
- its location; and
- particularly its connectivity to ephemeral flows and streams during rain storm events.
It is important to carefully plan winter crops and feed-out areas by utilizing the most appropriate paddocks on your farm as indicated in your farm’s LEP Land Use Capability (LUC) classes map and the risk analysis process via your LEP (see Section 9 of Landcare Manual).
Riparian protection and filter strips are an essential practice. In some cases, however, there is a risk that even they may not cope with the volume of sediment, nutrients and bacteria during heavy storms and especially so for dissolved reactive phosphate and E. coli.
Anywhere that storm water can flow through needs to be considered as a risk area. Muddy gateways and troughs, winter crops in valley floors, poorly located silage pits and winter self-feed structures can become 'Critical Source Areas' for contaminants especially in winter time. refer to pg 30 of Landcare Manual.
Feeding deer on feed pads with good surrounding shelter offers some protection to both the feed (reducing wastage) and the rested farm paddocks. However runoff from feed pads still needs to be directed safely to capture contaminants before they reach the water ways. Wintering hinds in woodlots in conjunction with self-feed silage pits effectively removes them from the pasture, providing pasture relief and protection plus the ability to save pasture for weaner growth and production over winter and into early spring. However, if the woodlot is on steeply sloping land with active winter waterways, soil and nutrient loss from this area can still be a problem and the net gain for the farm’s environmental footprint is questionable in this situation.
Sediment ponds or detainment bunds can be placed downstream of wintering areas to contain peak storm flows coming throug the wintering system. Their effectiveness is limited to capturing sediment and some particulate phosphorus. Residency time in still water in the pond is important as soil particles need to have time to settle out. To achieve a worthwhile residency time, sediment ponds need to have a storage to catchment ratio of not less than 100:1, i.e. 100 cubic metres of temporary pond storage for each hectare of contributing catchment.
Some regional Councils now have rules prohibiting stock access to waterways during the winter months from 1 May to 30 September. Get advice from your regional council for your area. For further information on best practice, click here >>
To download the module and related documents, click on the links below:
To download our handy Deer Fact sheets on winter grazing management and good environmental practice, click on the links below:
- Intensive winter feeding: minimising the environmental risk >>
- Planning for winter: best options for deer and their environment >>
- Protecting waterways from wallow and feed pad run-off >>
- Effective nutrient management on deer farms >>
- Farm Environment Plans: the whys and hows of preparing them >>
- Fence-pacing: costs and solutions >>