Manage the environmental impact of alternative winter systems

Read our advice on managing the environmental impact of winter systems for livestock. Includes tips on compaction, soil fertility and wet weather management.

It is important to manage the environmental impact of winter systems by planning ahead. Consider the following points to avoid issues later on:

• Field selection should account for soil type and grazing duration and direction to reduce run-off
• Back fence the crop every 4–5 days to reduce poaching
• Use portable water troughs and ring feeders to prevent feed contamination
• Start grazing from the top of a slope, as this can reduce phosphate loss by 80% and soil and nitrogen loss by 90%
• Fence off ditches and streams and maintain buffer strips around the field
• Use outwintering as part of a planned crop rotation or grass reseeding strategy to remedy any compaction
• Put bales out before winter to avoid driving over the crop in wet weather
• Think about your stocking rate in advance so that there are enough bales ready in the field

It is essential to have a strategy planned for severe weather conditions. This may include:

• Larger allocation or ‘break’ of crop
• An additional dry lying area or alternative shelter
• Providing additional conserved forage
• An alternative grazing area
• Housing animals
• Stand-off pad
• A supplement with concentrates

The lower critical temperature (the temperature below which the animal starts to use feed to produce heat to stay warm) for an acclimatised cow in dry, still conditions is -18°C. For an un-acclimatised cow in wet and windy conditions, it can be +7°C.

In very poor weather, some or all animals may have to be removed from the field and housed. Ensuring that water troughs and pipes do not freeze during the winter is also important.

Monitoring rainfall can aid in deciding on contingency plans and has been shown to help reduce pollution.

Remember to move stock immediately to other land or housing if soils become poached (hoof prints deeper than 50 mm or two inches) or brown water run-off is apparent.

If managed poorly, outwintering livestock can pose diffuse pollution risks alongside a possible loss of valuable soil and nutrients. Outwintering can lead to poaching around gateways, ring feeders, and water and feed troughs.

Research has found little difference in soil conditions after outwintering on grass, kale or fodder beet if the soil type has been considered for crop choice. In an AHDB study, soil compaction increased post-grazing in grass, kale and fodder beet, with little difference between crops.

Research has shown that compaction from outwintering livestock tends to be concentrated in ‘high traffic areas’. These areas often only account for 5% of the field and do not affect average pasture growth in the following season.

Consider reassessing soils following outwintering by following our simple How to assess soil structure (VESS) guide.

For deferred grazing/AGW, soil compaction can be prevented to some extent with flexible grazing management. During dry weather, where practical, graze the fields with heavier soils or temporary leys to avoid depending on them during wet weather. In wet weather, shifting more frequently and reducing stocking density can limit damage.

Carrying out regular soil tests is essential to monitor soil fertility and whether this is limiting grass growth. The targets to aim for are:

• pH of 6.0–5
• Phosphate (P) Index 2 (16–25 mg/l)
• Potash (K) Index 2- (121–180 mg/l)
• Magnesium (Mg) Index 2 (5–100mg/l)

The manuring and urination of grazing animals will recycle phosphate and potash . This will be more evenly spread than in set stocking systems, meaning levels of phosphate and potash should not be a problem. Placement of fences along contour lines will stop the build-up of phosphate at the top of the slope where ewes prefer to lie and then defecate.

Nitrogen deficiency may be an issue, particularly if clover content is low. This is shown with a yellow tinge and paler green colouring of the leaves. Nitrogen applications in August (at the latest) of around 30–50 kg/ha of nitrogen (24–40 units/acre) will boost grass growth going into the winter.

Research has shown the highest risk period for nitrogen losses after outwintering grass paddocks are April–July. Nitrogen losses are minimised if farmers reseed rather than rely on natural regeneration. If planning to reseed, ask a seed merchant about varieties bred for out-of-season growth and good winter hardiness. Always buy seeds mixtures with varieties that feature in the Recommended Grass and Clover Lists. 

Grass wintering may conflict with some biodiversity goals surrounding ground-nesting birds and growing multispecies swards. Check the environmental stewardship options for the farm to ensure there are no conflicts and consider maintaining areas of less productive land for biodiversity purposes.

If you would like to order a hard copy of any of the following publications, please contact publications@ahdb.org.uk or call 0247 799 0069:

• Using brassicas for Better Returns
• Nutrient management guide (RB209)
• Recommended grass and clover lists 
• Healthy grassland soils pocketbook