Wintering feed systems
Wintering feed systems
Effects of winter on the environment
Winter can be a critical time for erosion of soil on deer farms. Some types of wintering systems, especially cultivated paddocks with brassica/swede fodder crops, pose particular risks to water quality as the exposed soils can be saturated, prone to muddying and being carried away during rain storms into waterways. As well as carrying soil particles, this runoff water contains a cocktail of phosphorus, nitrogen and faecal coliforms that are a risk to downstream water quality.
Designing wintering feed systems
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.
Winter feed pads
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.
Stock access to waterways
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 see http://www.es.govt.nz/environment/farming/winter-grazing/.
- Sound risk planning via your LEP
- Plant feed crops away from waterways
- Do not cultivate and plant winter crops through the low points or swales
- Leave water flow paths (ephemerals) in grass and temporarily fence them off when winter grazing
- Break feed towards the waterway
- Back fence stock off land that has already been grazed
- To minimize tractor damage, place baleage in paddocks before winter
- Consider low-till or no-till methods for establishing winter crops