11 March 2025

Spring fertiliser and grazing management tips for sheep farms

From a management, cost and labour point of view, turning ewes out to grass as they lamb with minimal supplementary feeding must be the aim on sheep farms, Dr. Philip Creighton tells us more.

All going according to plan and having started your grazing plan for this spring last autumn, ewes can be turned out to grass as they lamb with minimal supplementary feeding, if any, required post turn-out. From a management, cost and labour point of few, this must be the aim.

Nitrogen

An early application of nitrogen is an important step to boost and maintain grass supply during early lactation for ewes with an increasing feed demand. Suitable conditions and considerations to take into account when planning an application of early nitrogen to grassland swards include:

What is the soil temperature?
- Minimum 6^OC and rising is required for growth.
Are ground conditions suitable?
- Do not spread on wet soils – possible N Loss and soil damage. Also ensure at least 48 hours without heavy rainfall are forecast after application.
Is grass actively growing?
- Fields with a high perennial ryegrass content and fields with a cover of grass of greater than 400 kg DM/ha (5cm) should be targeted. Fields with lower grass covers should be targeted for slurry or FYM application where available.
How much to apply?
- Do not apply more than 30kg N/ha (24 units/ac) in one application. Amount required will depend on feed demand. Typical requirements for sheep farms will range from 20kg N/ha (17units/ac) for farms stocked at less than 10 ewes/ha up to around 30kg N/ha for farms stocked at 12 ewes/ha or more.

Managing nutrients

It is worth bearing in mind that response to applied nitrogen is also dependant on overall soil fertility. If you have not carried out a soil test recently now is the perfect time to do so before you apply any fertiliser or manures. The results can be used to produce a nutrient management plan appropriate to your farm. Fertiliser can account for up to one fifth of the total variable costs on sheep farms so effective management of this commodity has potential to save money. A liming programme should be in place on all farms in order to have soil pH at its optimum year on year. This will prevent soil pH from dropping to such an extent that the release of nutrients and the response to applied fertiliser will be compromised.

Grazing management

Set stocking / continuous grazing systems are commonly operated on Irish sheep farms, with sheep grazing the same grassland area throughout the grazing season.

Rotational grazing systems offer greater flexibility in grassland management by providing increased control over sward structure, grazing severity, regrowth periods and overall pasture supply.

This involves dividing the grassland area into a number of paddocks, which are then grazed, fertilised and rested in turn and can allow greater levels of herbage utilisation be achieved.

A general recommendation with regard to paddock size taking an example of a farm with a flock of 100 ewes stocked at 10 ewes/ha would be a minimum of 5 paddocks of 2ha (5ac) each per grazing group, which can then be further divided using temporary fencing as required.

By subdividing the paddocks sheep are moving every 2-3 days. This keeps fresh grass in front of the sheep and allows the area to be grazed quickly to allow grass to begin growing again. This form of grassland management maximises grass growth and utilisation while maintaining animal performance as quality is more easily controlled.

Key grazing targets for an early March lambing flock are:

Aim to stretch the end of first rotation to mid-April (40 days) when hopefully growth will be matching demand;
20% to be grazed, fertilised and re-growing by mid-March;
40% to be grazed, fertilised and re-growing by end of March;
Mid-April first rotation complete and sheep return to paddock 1 (having had a month to regrow) to commence second rotation, ideally divided in two with temporary electric fence.

More from Teagasc Daily: Key tips during lambing