The phasing out of some pesticides is resulting in a resurgence of the break crops grown on UK farms.
They can be a good fit within a reseeding programme, but a downside is that they take fields out of grass production.
However, with many farms not achieving their yield potential, grazing lost to catch crops can be balanced if steps are taken to improve overall yield per hectare, says independent grassland and forage specialist Charlie Morgan.
Many farms are only yielding 5t DM/ha but have the potential for 10-12t DM/ha, he warns.
“This means there is the potential to double the yield, which means more land is available to grow these crops.”
But with multiple catch crop varieties on the market, which ones should sheep farmers opt for?
“The three main questions farmers have to ask themselves is when do I want to graze it, what do I want it to feed and when will the field become available for sowing,’’ advises Mr Morgan.
Here we examine the different options.
Note that growing costs will vary according to whether the seed is drilled or broadcast.
See a table comparing forage rape, hybrid rape/kale, stubble turnips and fodder beet (PDF)
Top tips for grazing catch crops
- It is essential that sheep graze both the leaf and stem of forage crops or the value of protein in the leaf will be lost. The leaf is where the protein is, but the stem holds the energy so protein will go straight through the animal if it doesn’t graze the stalk to capture it.
- Aim to graze each stem to 12cm (4 inches); this also provides the opportunity for re-growth if back-fenced. Back-fencing can be used if water and fibre sources are accessible.
- Give sheep-grazing forage crops a trace element bolus or drench, because what they provide in feed value they lack in trace elements.
- Strip grazing catch crops is key to achieving a good utilisation rate – limiting access initially allows sheep to be introduced gradually to their new diet.
- Grazing smaller blocks reduces trampling and wastage but, on very wet days, allow sheep access to larger areas to reduce stocking density at the feed face and lower the risk of soil damage and run-off.
- If the crop is planted on sloping ground, graze the field from the top down to minimise risk of soil run-off; multiple access points will reduce poaching at runback sites.
- Fields used for growing catch crops should be those with lighter soils, good drainage and not be located near watercourses.
- On heavier soils, it can be advisable to direct drill the seed into previously sprayed off grass. The decaying sward creates a base to the crop. The roots, although dead, will help as an anchor to the soil, and the firmer surface will reduce the poaching impact.
Combining different varieties as an insurance
An insurance policy against a crop under-performing is to grow a combination together – for instance, forage rape can be sown with stubble turnips and hybrid kale.
“The conditions in the year of growing might not be favourable for rape but favourable for turnips, so blending these together provides a safety net against one of the crops failing or underperforming,” explains Mr Morgan.
One option is sowing Italian ryegrass with rape. This can be sown between April and September and will, therefore, be fit to graze in as little as 60 days.
If sown early enough, it can be grazed from July in the year of planting through to winter and the following spring.
“It is a versatile crop that provides grazing for finishing lambs and winter grass for ewes and lambs and will also provide a crop of silage,” he adds.