Winter Grazing

Planting a catch crop is a way of reducing the risk of nitrate leaching after winter grazing. After grazing a winter crop, there can be large amounts of residual soil nitrogen that is at risk of leaching. By planting another crop as soon as possible after your final grazing, you can capture those nutrients in the second crop and increase overall feed production from the paddock. This also protects the environment by reducing the risk of nitrogen loss to water. Research has shown that a catch crop can reduce nitrogen leaching by up to 40% in some soil types.

1. What soil type are you dealing with?
Free draining soils, -with a low water holding capacity and a small pore volume (e.g. stony soils) or soils with subsoil drainage (tile, mole, nova flow)-, are most at risk of nitrogen loss through leaching, although, free draining soils are also the most suitable for catch crops.
If you are dealing with heavy, wet, or water-logged soils the use of heavy machinery may damage soils. It is important, in this situation, to consider when and how you establish your catch crop. The soil may not dry out quick enough to allow you to work it up in time to establish a catch crop so look into other ways to established catch crops.
Consider the paddock topography and cropping history when looking at establishing a catch crop.

2. Is your soil dry enough to sow a crop?
Look at your paddock and consider the soil moisture before cultivating. Do not cultivate or disturb wet or water-logged soils before they have dried out. Consider no till sowing methods, such as direct drilling, Heli cropping or broadcasting. Try to get your catch crop sown as soon as the soil is dry enough. Catch crops are a good way to retain and utilise the nitrogen that remains in the soil after grazing a crop that could otherwise be leached during winter drainage events.

3.       Choosing the right crop for your paddock.
Consider all your options & limitations:    

• Will this crop germinate and grow at low temperatures?  
•  A cereal crop such as winter oats or Rye corn may be used as an effective catch crop. 
• Will you either feed the crop directly to animals or will it be harvested and conserved for a time when feed is in short supply? 
• Carefully consider using catch crops in dryland situations as they will remove moisture from the soil through transpiration and may reduce the available moisture for subsequent crops.

Relevant resources

The following resources are relevant to all livestock farmers – dairy, beef, sheep and deer – who graze pasture or crops intensively over winter. If you would prefer face to face guidance on these or other environmental issues, you can attend one of B+LNZ's Farm Environment Plan or Land Environment Plan workshops. View the B+LNZ Events Calendar for upcoming dates.

Winter Forage Crops: management after grazing (PDF)
Catch Crops: A Way to Reduce N Leaching after Winter Crops, Dr. Brendon Malcolm, Plant & Food Research (Podcast)
Two wins from using a Catch Crop (Dairy NZ)
Catch Crops (Lincoln Agritech)
Catch Crops (Dairy NZ)
Forages for reduced nitrate leaching programme (Dairy NZ)
Guidelines for Catch Crops (Forages for Reduced Nitrate Leaching)

1. Understand the risks of winter grazing 
Winter grazing can increase the risk of sediment, harmful bacteria and nutrients ending up in water. Reducing this risk begins with paddock selection. Paddocks with water flowing through or over the soil present the most risk. For example: paddocks with sub soil drainage systems, paddocks on slopes or paddocks with stony free draining soils. 

Once that you have identified that you have suitable paddocks to reduce the risks, you can think carefully about:

1) establishment methods,

2) how they will be grazed and

3) what animals will be grazing them.

4) It is also important to consider your catchment-specific water quality issues when selecting paddocks for winter feed crops. 

In catchments where nitrogen leaching is a problem, be aware that growing and intensively grazing crops increases the risk of nitrogen leaching so avoid intensively winter grazing on shallow, stony soils.
In catchments where phosphorus and sediment loss are the main issue, focus on the proximity to waterways and reducing overland flow

If a paddock is too steep to get a tractor on, it is too steep for wintering cattle. We recommend you don’t crop paddocks or areas in paddocks steeper than 15 degrees.
To slow down water and soil moving down the hill you could, consider cultivating and sowing across the slope, this reduces nutrient and soil loss. However only when it is safe and practical to do so do not attempt this when the slope is not too steep.

2. Consider the risks in each paddock
Make sure winter feed crop paddocks are set right back from all waterways or wet areas, we recommend a buffer of at least 5 meters. This will reduce the risk of topsoil, phosphorus, nitrogen and fecal contaminants reaching water bodies. Identify Critical Source Areas (CSAs) which are areas that are prone to surface run-off and contaminant-loss such as gullies and swales. CSAs should ideally be left intact and not be sprayed, cultivated, sown in crop or grazed. They should be fenced off during grazing to reduce the risk of contaminating waterways. 

Soil type can impact productivity, nutrient loss & animal welfare. If you have light or stony soils, seek advice on using catch crops to capture nutrients.  Consider only grazing lighter classes of stock on heavy soils during winter. Heavy soils are at greater risk of pugging, compaction and structural damage.   If your soils are prone to pugging, consider leaving areas of the paddock in grass for animals to rest on. 

Damage to soils from poor grazing management of winter crops will impact on the future productivity of that paddock.

Take note of local regulations, some regional councils have specific regulations in place.

3. Other factors to consider when selecting paddocks for winter forage crops

• What class of stock will you be grazing in that paddock? Consider using high risk paddocks only for wintering sheep while lower risk paddocks can be used for cattle and deer. 
• Consider the aspect– is the paddock north or south facing? South facing paddocks may be slower to dry out and therefore more prone to pugging. 
• Think about catch-crop options- The quicker a follow-up crop is established after the feed crop has been grazed, the less chance of losing valuable nutrients. 
• Animal welfare factors- Is there appropriate shelter and somewhere free of mud for livestock to lie down. 
• Is there drinking water in the paddock, where are the troughs, are portable troughs required? 
• Is the paddock easily accessed- Even in winter? Ideally supplementary feed should be put into the paddock prior to grazing to reduce heavy traffic on wet soils. 
• Consider biosecurity- Ensure your stock – particularly cattle – don’t have nose-to-nose contact with your neighbor's animals.
• Make sure you adhere to all local regional council rules and regulations around winter grazing
• If you have no suitable paddocks on your property, you will need to have a look at your farming system. This might require a long-term vision until then, minimising risks would be key. Increasing buffer zones, using lighter stock classes, leaving higher residuals and using stand-off areas would be options to minimise risk.

Relevant resources

The following resources are relevant to all livestock farmers – dairy, beef, sheep and deer – who graze pasture or crops intensively over winter. If you would prefer face to face guidance on these or other environmental issues, you can attend one of B+LNZ's Farm Environment Plan or Land Environment Plan workshops. View the B+LNZ Events Calendar for upcoming dates.

Top Tips for Winter Crop Paddock Selection (PDF)
Paddock Selection WoF (PDF)
Winter Forage Crops: management before grazing  (PDF)