Kale or Rape as a Winter Forage Crop – Is it worth it?

By Míchéal Kelly, Drystock Adviser, Teagasc, Galway/Clare

As the age old saying goes – ‘Fail to prepare, prepare to fail’. This could not ring more true for winter feeding. As we are approaching the summer, many farmers are enquiring in the office here about the effectiveness of using a forage crop to sustain their young stocks daily growth rates, as opposed to traditional methods of winter feeding such as silage and hay. A popular idea has been Brassicas like kale and rape. 

With inflation affecting many aspects of agriculture, one of the most glaring areas is the prices of conserving silage. Farmers wishing to save silage this year are being met with rising prices, as FCI (The Association of Farm and Forestry Contractors in Ireland) are presenting ‘modest increases’. Below is a table comparing 2022 prices vs 2023 prices.

A local co-op has quoted me €172 for a roll of 60ft x 110ft silage cover, where 2-3 covers may be needed for the pit. The same co-op maintain it costs €115 for a roll of silage wrap which would cover approximately 25 bales.

While pit silage hasn’t seen as drastic of a change, these figures are pushing farmers away to more cost effective methods, such as sowing Brassica crops as a winter forage crop.

What is a brassica crop?

Brassicas are a group of leafy plants, which includes broccoli, Brussel sprouts, turnips, kale, rape and many more. They need lots of space between them to grow as they are quite leafy, who will compete for water and nutrients. Brassicas are high in energy and protein.

Brassicas are good cover crops as they are very leafy plants that grow rapidly, which will shade the soil efficiently. This will block sunlight for competing weeds, acting as a weed cover.

To add to this, Brassicas generate chemical compounds called glucosinolates which are natural inhibitors of weed growth. Brassicas are also very good for breaking up compacted soil. Rape for example has a long tuber which will reach far down into the soil and break it up, helping naturally aerate the soil.

Brassicas come in many varieties. There are winter variants which are used specifically to weather harsh winters and there are hybrids also, which can feature two brassicas in one crop, allowing farmers to reap the benefits of both. However, it should be noted that rape in particular must be grazed before its flower starts to emerge as this is toxic to livestock.

Brassicas are naturally low in essential vitamins like Iodine, Selenium, Copper and Cobalt, so boluses or mineral lick buckets are required.  Additionally, rape that has been covered by frost is dangerous to graze also. Frost can increase the level of nitrates in the rape which can be poisonous and can be fatal to cattle.

Farmers need to also take care that they adhere to Nitrates Regulations – they must ensure there is no run-off or excess poaching, as this can become an issue when out wintering stock.

Finally, Brassicas should be introduced to the herd or flock gradually alongside some roughage like hay silage or grass. This is mainly because Brassicas are low in fibre. Without this, your stock may gorge on the crop and induce digestive issues in the rumen, so adlib roughage and fresh water is needed to counteract this.

Roughly what is the cost of sowing Rape or Kale?

FCI maintains it costs about €52-€59 per acre for ploughing depending on stubble or lea, with the disc harrowing (if needed) costing €40 per acre also. The need for de-stoning must be considered as well, depending on the field. Rolling costs about €16/ac as well (if needed).

The Nitrogen, Phosphorus and Potassium needs of forage rape are depicted in the table below.

It costs about €50/tonne to spread, broadcast or bulk, according to FCI. Boron Sulphur and Magnesium are very important elements for growth, especially Boron. Farmers should consider soil testing for these elements and adding them to their fertilising plan accordingly.

The optimum pH of Kale and Rape is 6.5-7, and this can be achieved by spreading lime. Fortunately for farmers, the National Liming Programme 2023 offers a grant of €16 per tonne of lime spread, from a minimum of 10 tonnes to a maximum of 200 tonnes, which is an excellent subsidy.

I was quoted from a local co-op at €34.80 and €71 for a type of rapeseed in 10kg and 25kg bags respectively. 3.33kg/ac is needed for broadcast spreading the seed, whereas 2.5kg/ac will suffice for direct drilling.

Direct drilling is an enticing option as it ensures the ground is firm and will prevent poaching from heavier beef animals. FCI quotes that direct drilling would cost €62-€65 per acre.

Which stock would be ideal for winter forage crops?

In a beef based system, younger stock like weanlings and yearlings could be kept out all throughout the winter, being strip grazed on the rape. The high energy and protein content will see generous growth rates in these animals, as high as 0.7-0.8kg gained per day for weanlings first winters, compared to in wintered weanlings which average at 0.6-0.7kg gained per day, with no added meal.

Additionally, keeping these younger stock out can free up pens in your winter housing and allow for more comfortability when carrying out winter activities like calving, vaccinating, and dosing. These stock can be sold for a net profit due to the lower input cost of growing winter forage.

On the other hand, in a sheep based system, autumn lambs kept out on forage over the winter can avail of much higher prices at Christmas and New Year’s sales. Sheep need to be monitored closely though, as the Brassicas will grow taller than them and soil and plant remains can get caught in their wool. This can be a breach of the Clean Livestock Policy, meaning you might not be able to slaughter your sheep due to the potential cross contamination arising from sheep grazing Brassicas.

To conclude, winter forage is certainly worth considering, if you are ready to input the labour and understand the risks and rewards of sowing Brassicas.