Time running out for best results from kale

With the potential to yield 8-12t/ha of dry matter (DM), farmers may be looking at kale as an alternative to bolster fodder reserves next winter.

Kale has a high feeding value, with a dry matter digestibility (DMD) of >80% and a UFL/kg content of 1.03-1.05. It’s the equivalent of early spring grass in terms of quality. It also has a high level of crude protein (16-18%), which helps to promote animal growth.

As it takes kale approximately 150 days to reach maturity, farmers planning on sowing the crop really need to get it in over the coming days to achieve the best results.

Crops sown in mid-June – permitting they are provided with the right conditions and fertiliser inputs – will generally generate high yields.

Seeding rate

When it comes to seeding rate, kale may be precision drilled at 3kg/ha, direct drilled at 4-5kg/ha or broadcast at 5-8kg/ha.

Like grass, a fine, firm seedbed and moisture are essential for rapid emergence; the surest method of establishment is through ploughing and powered cultivation. However, in well-structure soils, direct drilling will also be successful.

Tillage, Tyres,

Fertiliser requirements

Kale grows best on well-drained soils with a pH of 6.0-7.0. Unlike other members of the brassica family, kale is not as sensitive to boron deficiency.

Slurry or farmyard manure applied pre-ploughing will normally provide enough boron for the crop. Where this is not applied, the use of a boron-enriched fertiliser should be considered.

Slurry nitrates derogation, ammonia spreading slurry
Image source: Shane Casey

When it comes to the nitrogen (N), phosphorous (P) and potassium (K) requirements of kale, Teagasc recommends the following application rates for a crop grown in an index 3 (both phosphorous and potassium) soil :

  • Nitrogen – 130kg/ha;
  • Phosphorous – 30kg/ha;
  • Potassium – 170kg/ha.

Club root

Club root is the main disease threat. However, kale is not as prone to the disease as other members of the brassica family.

A one in five year rotation is suggested to keep club root levels low. Grampian and Caladonian are tolerant of club root. However, these varieties do not reduce the levels of the pathogen in the soil and, as a result, subsequent brassica crops may suffer from the disease.