Agronomy Advice
August 23, 2018

Fertilising short term leys and forage brassica crops

By: Philip Cosgrave

It is important for short term leys and forage brassica crops to get off to a good start and getting the seedbed fertilisation right is a big part of this.

Fertilising short term leys and forage brassica crops
Fertilising short term leys and forage brassica crops

The interest this autumn in short term leys and brassicas is phenomenal but hardly surprising as farmers do whatever they can to fill a forage shortfall caused by a late spring and an extended drought.

Short term leys and brassicas need to 'hit the ground running'

Fertilising these crops adequately is necessary to obtain the yields they are capable of producing. In general these crops are being sown after a cereal crop and therefore the soil nitrogen supply is likely to be low.

With temporary leys following cereals Yara recommend up to 50 kg/ha of nitrogen, 20 kg/ha of phosphate (P) and 40 kg/ha of potassium (K) applied at drilling. The phosphate in particular is important for root development and tillering. YaraMila Actyva S (16-6.6-12.4 + 2.6% S) contains ‘P-Extend’ which will provide a consistent and reliable supply of phosphate for the remainder of the growing period. Not forgetting that these fast growing grass leys have a requirement for sulphur which is often forgotten.

Remember that the N requirement for every 1cm of grass growth is 7.5 kg/ha. We would expect Italian ryegrass or Westerwolds to grow to a minimum height of 10 cm by the end of October which will require 75 kg of N. If we apply 50 kg of N from the bag, there will be enough soil residual N to provide the remaining.   

P-Extend provides a consistent source of phosphate

The hybrid brassicas such as Redstart and Interval may still be drilled into late August and they have similar nutrient requirements to that of forage rape and stubble turnips. We recommend up to 80 kg/ha of nitrogen, 10 kg/ha of phosphate (P), 40 kg/ha of potassium (K) and 12 kg/ha of sulphur (S). A perfect fit for these nutrient
requirements is YaraMila Silage Booster (20-2-12 + 3% S +
Se) with ‘P-Extend’.

Preferably on these short term leys and brassicas, the fertiliser should be incorporated into the seedbed and not broadcast afterwards. If the option exists when drilling the brassicas to use a drill which will combine the fertiliser application also then this would be advantageous for the quick establishment of the seedling.

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Latest advice background
Grow the future | Grassland Sulphur Grow the future | Grassland Sulphur

Spreading nitrogen and sulphur at the same time means more grass

Applying fertilisers containing nitrogen and sulphur means the grass uses nitrogen more effectively, you get more kgs of dry matter per kg of nitrogen that you apply

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